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The comparative behavior of yttrium and lanthanides in the seawater of the North Pacific
Geophysical Research Letters
Abstract
Yttrium has long been recognized as an ekalanthanide, because of its chemical contiguity relative to the chemistries of rare earth elements which are, in recent years, intensively utilized for elucidation of metal scavenging processes in the ocean. Here, we present the first detailed depth-profile of Y(III) in seawater together with the lanthanides in the North Pacific Ocean. The concentrations of Y(III) range 70–290 pmol/kg and show the “nutrient-like” profile best resembling that of Ho(III) amongst the other rare earth elements. The results agree well with an expectation based on the similarity in their ionic radii and hence stability constants of complexation with carbonate ions. Yet the Ho(III)/Y(III;) ratios in seawater systematically increase with depth, suggesting that Y and Ho are fractionated during scavenging by natural marine particulates. This is likely to result from the different complexation behavior in that Y(III) is more weakly complexed than Ho(III) with soft organic ligands on the surface of particulate matter during scavenging in the surface water but, once released into seawater in the deep sea, Y(III) is complexed with carbonate ions equally or stronger than Ho. The pattern of deep water enrichment in the lanthanide series appears to be consistent with the recent observation of partitioning between suspended particles and seawater. Our precise measurements also indicated that Pr and Tb best resemble Nd and Dy, respectively in their oceanic behavior, whereas Ho and Tm are intermediate between their neighboring rare earth elements.
... The REE results were normalized to PAAS (Post Archean Australian Shale) using data from Taylor and McLennan (1985) and McLennan (1989). Yttrium was also included because it is classified as a rare earth element (REE) due its chemical properties that are similar to those of HREEs (e.g., Bau and Dulski, 1996;Gong et al., 2021;Zhang et al., 1994). The calculation of Ce/Ce* = 3Ce N /(2La N + Nd N ) and Cerium anomaly Ce an = log Ce/Ce* are taken from Wright et al. (1987), the calculation Eu/Eu* = Eu N /(Sm N + Gd N ) 0.5 is taken from Taylor and McLennan (1985), Pr/Pr* = 2Pr N /(Ce N + Nd N ) is from Bau and Dulski (1996) and Y/Y* = 2Y N /(Dy N + Ho N ) calculation is from Fazio et al. (2007) (See Appendix 1). ...
... In phosphorites, Y is often inserted between Dy and Ho in the REE series according to its ionic radius (e.g., Bau and Dulski, 1996;Zhang et al., 1994). Similar to REE-enriched glauconites of Bled El Hadba phosphorites, Y is also more enriched in glauconite minerals compared to pellets and coprolites, where the contents are slightly lower (Fig. 7a). ...
... Y and La/Nd anomalies, which are positive in seawater, do not change with redox conditions but their values can be helpful to assess the effect of diagenesis in depositional environment (Bau, 1996;Fazio et al., 2007;Shields and Stille, 2001;Zhang et al., 1994). Shields and Stille (2001) reported that Y/Y* and La/Nd ratios of modern seawater are 1.5-2.3 and 0.8-1.3 ...
Rare earth element (REE) enrichment in Algerian phosphorites has been evoked recently by a number of authors and are considered amongst the richest Paleocene-Eocene phosphorites worldwide. The Bled El Hadba deposit belongs to the giant Djebel Onk phosphorite complex in northeast Algeria. The deposit was subject to many geological studies that were focused on P 2 O 5 contents for commercial purposes. The upper Thanetian phosphorite layer is about 30 m thick, and subdivided into three sub-layers (lower, main and upper sub-layer), based on P 2 O 5 contents, where the main sub-layer is considered to be the richest. Despite this, few detailed geochemical investigations were carried out on this deposit thus far. In this work, major, trace and REE analyses were conducted on phosphate particles (pellets, coprolites and glauconites) using 'in situ' LA-ICP MS, and on whole-rock samples using XRF technique. The results show that the main sub-layer displays the highest whole-rock P 2 O 5 contents, varying between 19.65 and 21.32 wt% compared to the lower (10.47-16.87 wt%) and upper (9.43-13.87 wt%) sub-layers. Amongst the phosphate particles, glauconites display the lowest P 2 O 5 contents in the three sub-layers (17.45-19.35 wt%) compared to pellets (21.14-24.33 wt%) and coprolites (21.75-24.12 wt%), and largely the highest Al 2 O 3 , SiO 2 , MgO and Fe 2 O 3(t). Glauconites also show higher REE contents (764-2050 ppm) compared to pellets (221-910 ppm) and coprolites (214-909 ppm). Within the glauconite particles, the REE, along with Al 2 O 3 , SiO 2 , MgO, and Fe 2 O 3(t) contents, increase from core to the rim, whereas P 2 O 5 contents decrease, which suggests that glauconitization postdates phosphatization processes. Also, the glauconitization process increase from the lower to the upper sub-layer; this is shown by the positive correlations between Al 2 O 3 contents and those of MgO and SiO 2 in one hand, and negative correlations between Al 2 O 3 and P 2 O 5 on the other hand. Ce, Eu, Y anomalies, along with La/Nd ratios and Nd contents, all point towards phosphatization under oxic conditions as a result of warm water upwelling, whereas glauconitization started under more reduced (sub-oxic) conditions; i.e., during early diagenesis, the peak of REE uptake from porewater, and under slow sedimentation rates. Despite their relatively low P 2 O 5 concentrations, the REE contents of the Bled El Hadba phosphate particles record the highest concentrations in all Algerian and north African phosphorites. The main sub-layer is considered to be the most glauconite-rich phosphorite in Algeria. Therefore, more extensive REE analyses are recommended to better evaluate its economic potential in terms of critical raw materials.
... The REY concentrations of extracted carbonatefluorapatite (CFA) phase for select phosphate rocks samples show its predominant contribution to the total REY in phosphate rock (i.e., ranging from 57% to 98% with an average of 80%, n = 11); therefore, the REY composition in the phosphate rocks directly reflects the CFA phase, even in rocks with relatively low percent of CFA (Table S3) (Bau and Dulski, 1996)), no Eu anomalies (i.e., Eu/Eu* ~ 1; Eu/Eu* = 2Eu N /(Sm N + Gd N ) (Bau and Dulski, 1996)), and positive Y anomalies (i.e., [Y] (Table S1; Fig. S6B). These REY geochemical fingerprints reflect the inherited features of a marine depositional setting (Bau et al., 1995;Zhang et al., 1994). In contrast, igneous phosphate rocks are highly enriched in light REY and depleted in heavy REY and tend to show weak negative Ce anomalies, strong positive Eu anomalies, and absence of or negative Y anomalies (e.g., phosphate rocks from South Africa and Russia; (Emsbo et al., 2015;Jarvis, 1995;Shields and Stille, 2001;Yang et al., 2019). ...
... The interaction with terrestrial fluids can also be reflected by the moderate positive correlation displayed between 206 Pb/ 204 Pb and Y/Ho for all the sedimentary phosphate rocks analyzed in this study (ρ = 0.50, p = 0.0003; Fig. 5C). As the terrestrial contribution increases, the Y/Ho ratio is expected to shift away from typical seawater values (i.e., Y/Ho = 40-70; Fig. 5C) due to the chemical fractionation between Y and Ho (Zhang et al., 1994). While Y is more weakly complexed with carbonate ions than Ho during scavenging in surface water, whereas in deep seawater, Y is complexed with carbonate ions equally or stronger than Ho, which explains why Y/Ho in terrestrial source is lower than that in seawater (Bolhar et al., 2004;Zhang et al., 1994). ...
... As the terrestrial contribution increases, the Y/Ho ratio is expected to shift away from typical seawater values (i.e., Y/Ho = 40-70; Fig. 5C) due to the chemical fractionation between Y and Ho (Zhang et al., 1994). While Y is more weakly complexed with carbonate ions than Ho during scavenging in surface water, whereas in deep seawater, Y is complexed with carbonate ions equally or stronger than Ho, which explains why Y/Ho in terrestrial source is lower than that in seawater (Bolhar et al., 2004;Zhang et al., 1994). Phosphate rocks from Israel, Morocco, Syria, and Jordan that have the most radiogenic 206 Pb/ 204 Pb ratios also have Y/Ho ratios close to the marine signature (Fig. 5C), suggesting less terrestrial input (Lumiste et al., 2021;Zhang et al., 1994). ...
... In addition, all samples in this study show similar characteristics in terms of Y/Ho ratio (Y/Ho = 35.5-40.4, average 40.5), which is much higher than the chondrite meteorite (Anders and Grevesse, 1989), and closer to the typical seawater Y/Ho ratio (Zhang et al., 1994;Nozaki et al., 1997). This indicates that the samples in this study can still reflect the seawater environment to some extent. ...
... All these results could indicate a gradual weakening trend of hydrothermal activity from the Cambrian Fortunian Stage to the Stage 2 (He et al., 2020;Zhang et al., 2020). In addition, the comprehensive rare earth distribution shows that all three sections in the Tarim region have negative Ce anomalies ( Figure 4) and Y/Ho ratios close to seawater (Zhang et al., 1994;Nozaki et al., 1997) (Y/Ho = 13.83-50.95, average 39.56, with some samples having lower Y/Ho ratios, as shown in Table 1), indicating that the sediment in the early Cambrian of the Tarim Basin did indeed record information from both hydrothermal fluids and seawater, or that the elemental characteristics in the sediment were simultaneously influenced by hydrothermal fluids and seawater . ...
The early Cambrian period is a critical time in Earth’s history, marked by the second oxygenation of the atmosphere (known as the Neoproterozoic Oxidation Event) and the rapid evolution of animals, as well as the worldwide large-scale deposits. Polymetallic Ni-Mo deposits have been previously reported in the black rocks at the base of the Cambrian strata on the Yangtze Block, South China, while their genesis is still controversial, and their global occurrences are uncertain. Therefore, we conduct a comprehensive analysis of trace elements and rare earth elements in the black rocks at the base of the Yurtus Formation in the Sugaitblak section (SGT) in Aksu, Tarim Block, and then make a comprehensive study by combining our and other data from the Tarim and Yangtze Block. The distribution patterns of the trace and rare earth element data from our study and another two sections in the Aksu area have shown that the black rocks in the Tarim were strongly enriched in V, Sr, Mo, Ba, and U, moderately enriched in Zn, Cu, Cr, and Pb, and slightly depleted in Ni, and Co during the early Cambrian. These enriched elements could mainly originate from the waning hydrothermal fluids, and then precipitate and preserve in sediments under anoxic environment. The comparison of trace elements in the black rocks between the Tarim and the Yangtze Block suggests that the types of enriched metal elements in these two regions were different, and metal concentrations in the Yangtze Block were much higher than those in the Tarim by 1–3 orders of magnitude. This result indicates that there are no polymetallic Ni-Mo enrichment layers in the black rocks in the Tarim during the early Cambrian, and the widespread polymetallic Ni-Mo enrichments in South China have been more likely influenced by the local hydrothermal activity. It could be further speculated that the early Cambrian period may have been an active period for seafloor hydrothermal activity, with locally different chemical components in hydrothermal fluids. Abundant metal nutrients brought by these hydrothermal activities may have been a potential factor for the rapid evolution of life during this period.
... Nonetheless, the fractionation of Y and Ho ratios in low temperature aqueous solutions reveals averages of 44-74 (1993). c La/ Th versus Hf, diagram after Floyd and Leveridge (1987) for seawater and 90-120 for hydrothermal fluids, denoting non-chondritic behavior (Zhang et al. 1994;. Given that THC-1 has a Y/Ho ratio close to chondrite and shales, implying no relationship to seawater-like (e.g. ...
... Given that THC-1 has a Y/Ho ratio close to chondrite and shales, implying no relationship to seawater-like (e.g. Zhang et al. 1994;Bau 1996). Bulk composition of these rocks assessed using immobile elements during surface processes like La/Th versus Hf along with Th/Sc versus Zr/Sc plots (Fig. 9b-c), suggests they are from a mixed felsic and mafic sources (e.g. ...
Tourmaline is a valuable forensic mineral that contains a wide range of elemental components capable of reconstructing its geologic evolution. In this study, we developed detailed petrographic and geochemical research on tourmaline-bearing rocks and tourmalinites found surrounding the ca. 3.30 Ga rhyolite of the Gavião Block, northern São Francisco Craton. Two distinct types of mineral assemblages in the tourmaline-bearing rocks are recognized based on the presence of sulfides, oxide minerals, and carbonaceous matter. Along with these tourmaline-bearing rocks, tourmalinite samples are found. The mineral chemistry of tourmalines from the two types of tourmaline-bearing rocks reveals mainly schorl-dravite as tourmaline from a mineral assemblage containing quartz, tourmaline, pyrite, and hematite, and a diverse composition ranging from schorl-dravite, feruvite-uvite, and schorl-feruvite solid solutions for tourmalines present in the mineral assemblage that contains quartz, pyrite, and carbonaceous matter. The tourmaline composition is essentially foitite-schorl in tourmalinite samples. Most of the metasedimentary rocks studied have felsic and mafic source compositions. The interaction of hydrothermal fluid was crucial for the formation of sulfide and tourmaline minerals. However, distinct tourmaline origins are recognized in tourmaline-rich rocks, pointing out the relevance of sedimentary and metamorphic processes.
... A quick assessment of REE sources can be based on the Th vs ΣREE and Y/Ho vs ΣREE cross-plots (Li et al., 2017). In fact, high ΣREE (sum of all REE content) and strong LREE (light REE, i.e., sum of La and Ce) and Th enrichment characterize the pore-water contribution (McLennan, 2001;Peppe and Reiners, 2007;Shen et al., 2012;Wright and Colling, 1995); on the other hand, high Y/Ho are indicative of an hydrogen signature as, in modern ocean water, Ho is adsorbed or complexed at about twice the rate of Y (Nozaki et al., 1997;Zhang et al., 1994;Zhang and Nozaki, 1996). More difficult is the interpretation of MREE (middle REEs, i.e., sum of Pr, Nd, Sm, Eu) and HREE (heavy REEs, i.e., sum of Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) enrichments as their contribution could reflect an authigenic phosphate signal (Bright et al., 2009;Reynard et al., 1999;Sholkovitz and Shen, 1995), further complicating the interpretation of the results. ...
... The Y/Ho ratio is particularly useful for distinguishing marine vs lithogenic REE sources. In fact, Y and Ho have similar ionic radii and show an analogous vertical distribution profile in modern oceans (Zhang et al., 1994); nevertheless, as mentioned in the Introduction, Ho in waters is removed (adsorbed onto suspended particulate matter or bound by complexants) twice as fast as Y (Bau, 1996;Nozaki et al., 1997;Zhang and Nozaki, 1996). For this reason, the lithogenic sources of REE are characterized by relatively uniform and low Y/Ho ratios, usually between 20 and 30, while seawater shows much higher values, mostly ranging between 60 and 70 (Kamber and Webb, 2001;McLennan, 2001). ...
... In contrast to this, REY SN pattern with positive Y anomalies of rapidly precipitated modern hydrothermal ferromanganese precipitates is scavenged without important fractionation Bau and Dulski 1994;Cox et al. 2013). Seawater is characterized by positive Y anomalies (Zhang et al. 1994;Bau et al. 1995). As a result, the slight negative to commonly positive Y anomalies of the Tafak Mn-ore samples (Fig. 7a) reflect that they may be recognized to the fluctuation of slightly slow, but mostly rapid rates of precipitation. ...
... Interpretation of the presence or lack of a Ce anomaly is often complex due to the anomalous behavior of La (Bau and Dolski 1996). Positive La and Gd anomalies with the negative Ce anomaly have been reported from modern seawater (Zhang et al. 1994). Ce/Ce* and Pr/Pr* values of modern deep and shallow oxic seawater are given by Alibo and Nozaki (1999) and Nothdurft et al. (2004) (Fig. 7b). ...
In Turkey, radiolarian chert-hosted Mn-oxide deposits are exposed commonly within the deep-sea pelagic sediments belonging to the ophiolitic mélange units along northern branch of the Neotethys (İzmir-Ankara-Erzincan Suture Zone) in northern Turkey. In the Tafak region (Dursunbey, Balıkesir), Mn-deposit is currently mined from large- to medium- scale lenses (ca. 10 × 100 m) and interlayers with the mudstone and silicious pelagic sediments. This deposit comprises dominantly mineral assemblages of braunite, pyrolusite, and ganque minerals are quartz and rarely calcite. High Mn/Fe (437), Co/Zn (1.36), Co/Ni (2.04) ratios, low contents of ΣREE (27.7 ppm), Cu+Ni+Co (303 ppm), and also negative Ce anomaly (Ce/Ce*PAAS = 0.46), positive Y anomaly (YSN/HoSN = 1.33) with Y/Ho ratio (36.09) suggest that Tafak Mn deposit formed in a submarine hydrothermal system. Redox-sensitive element ratios (Ni/Co = 0.23-1.45, V/Mo = 2.63–20.81), positive Mn*SN (3.03–5.04), low Sr concentrations (82.2 ppm) and Ceanom. (− 0.52) values indicate that the Tafak Mn deposit was formed in low-salinity and oxygenated marine environment. Meanwhile, the presence of weakly negative Eu anomaly (0.94), Ce anomaly (0.46), and ΣREE/Fe ratio (127.8 x10-4) suggests that low-temperature hydrothermal fluids (< 200 °C) in pelagic depositional site of the İzmir-Ankara-Erzincan Neotethyan Ocean were effective in formation of the Tafak manganese deposit.
... In deep waters of the West Pacific, the distribution of individual REEs is primarily controlled by conservative water-mass mixing. However, a minor fraction of their concentration is also influenced by non-conservative processes (Behrens et al., 2018b), such as scavenging, release from particles, and benthic input (e.g., Zhang et al., 1994;Nozaki et al., 1999;de Baar et al., 2018). The understanding of these non-conservative processes, particularly in the deep waters of the northwest Pacific, remain limited and highlights the need for further research. ...
In the North Pacific Subtropical Gyre, which is one of the largest oligotrophic regions, there is a lack of information regarding the sources and transport of trace metals through water mass mixing. Rare earth elements (REEs) are essential for tracing lithogenic sources and water mass transport. In this study, we present dissolved REE concentrations and the factors controlling their distributions in the northwest Pacific during a GEOTRACES cruise (GP09). In the surface water along 11°N, we observed input signals from the Philippine and the Hawaiian Islands, characterized by positive Eu anomalies and slightly elevated REE concentrations. By incorporating our data and published REE data from the northwest Pacific to the southeast Pacific (40°N–40°S), we demonstrated that the REE concentrations and Yb/Nd ratios can distinguish North Pacific Intermediate Water (NPIW), Antarctic Intermediate Water (AAIW), and modified AAIW. By estimating the ratio of water mass mixing, we suggest that heavy REEs are predominantly contributed by water mass mixing (e.g., 93 % ± 4% for Yb) and can be used as semi-conservative tracers to quantify the mixing of NPIW and modified AAIW at the potential density of 27.2 kg/m3. At ∼800 m depth at stations K12, K13, and K14, weak negative Ce anomalies (>0.1) were observed, indicating the lateral transport of water masses imprinted with sediment signals from the Philippine Islands. In the deep waters (>1500 m) at the Luzon Strait (station K1), we propose that the weak Ce negative anomalies (>0.08) and low Yb/Nd ratios (<5), combined with the low beam transmission, are the result of particle resuspension and release. In deep water (>2000 m), combining high-resolution REE measurements with water mass analysis, our research reveals that dissolved REEs (except Ce) are dominantly controlled by water mass mixing (e.g., 80 %∼100 % for Yb and 70 %∼100 % for Nd). For the non-conservative behavior, which is not explained by water mass mixing, the residual fraction of heavy REEs (<20 % for Yb) originates from release of sinking particles (organic matter and siliceous particles), while the remaining concentrations of light REEs (<30 % for Nd) may be influenced by a combination of particle release and scavenging processes. These findings highlight valuable information about lithogenic sources and the proportions of REE distributions that are controlled by physical and biogeochemical processes. Moreover, it emphasizes the applicability of heavy REEs as effective tracers for understanding basin-scale water mass mixing in the northwest Pacific.
... The Y/Ho ratio is varying from 22 to 36 in the columnar jointed basalts (with three samples presenting the value > 44) and from 24 to 31 in mafic dykes. The mean value (Y/Ho = 31) of all the columnar jointed basalts and mafic dykes are slightly over the value of 28 that is observed in fresh basaltic rocks [43] and below the values observed in altered rocks (between 44 and 74) [44,45] indicating globally that secondary processes were not significant on the studied rocks. ...
In the Central Cameroon Shear Zone, several studies were focused on granitoids and very few on mafic rocks. Here we report the petrography, geochemistry and mineralogy of the Mfengou-Manki mafic rocks in order to constrain their petrogenesis and tectonic settings and the role of lithospheric and asthenospheric mantle sources in their genesis. The studied mafic rocks are subdivided into columnar jointed basalts and mafic dykes. Clinopyroxene thermobarometry indicates that the mafic dykes crystallized at a temperature of 1071 to 1193 °C and a pressure of 4 to 12 kbar while the columnar jointed basalts emplaced at a temperature of 1064 to 1152 °C and 2 to 13 kbar pressure. The mafic dykes and columnar jointed basalts present high La/Sm, Sm/Yb, Nb/Yb and Th/Yb ratios, indicating garnet to spinel transition zone mantle source. The multi-element diagram of the mafic dykes display enrichment in Nb, Ta, Pb and Ti and depletion in Th, U, Ce and Zr compared to that of the columnar jointed basalts (slight depletion in Nb and Ta and pronounced depletion in U, Pb and Zr and enrichment in Cs, Ba and Rb) indicating the little involvement of the sub-continental lithospheric mantle to the formation of the columnar jointed basalts. The Nb/La ratio > 1 for the mafic dykes and < 1 for the columnar jointed basalts also suggest the derivation of the mafic dykes from the asthenospheric mantle and the columnar jointed basalts from the mixed lithospheric-asthenospheric mantle due to the sub-continental lithospheric mantle delamination under the Central Cameroon Shear Zone.
... A weak positive correlation between Y/Ho and Sr/Ba of the coal samples (Fig. 20A, r = 0.34) may indicate at least a part marine influence during the peat deposition. Seawater generally has a positive Y anomaly (Bau et al., 1996, Zhang et al., 1994, so the coals affected by seawater also have a positive Y anomaly . The three lowermost (SH-3-30, SH-3-31, SH-3-32) and the topmost (SH-3-1) coal benches of the coal seam have significant positive Y anomalies (Fig. 19E), indicating that the early and end stage of peat accumulation was significantly influenced by seawater. ...
... There is insufficient data (n = 3) from the 2017 survey in the fjord to comment about their mixing behaviour that summer, but the three measurements are compatible with the 2021 data (Fig. 3). Lanthanum is occasionally reported separately as its behaviour may deviate from other LREEs in seawater (Zhang et al., 1994;Zhang and Nozaki, 1996;Alibo and Nozaki, 2000). However, as can be appreciated from Tables 1 and 3, with a few exceptions, the La/Er and Nd/Er are very similar. ...
... Although not without controversial views, the contents of REE and HFSE have been widely used for paleoenvironmental reconstructions and, most importantly, to detect any diagenetic footprint (Armstrong et al., 2001;Chen et al., 2015;Herwartz et al., 2013;Holser, 1997;Kocsis et al., 2010;Liao et al., 2019;Medici et al., 2021;Picard et al., 2002;Reynard et al., 1999;Toyoda and Tokonami, 1990;Trotter et al., 2016;Trotter and Eggins, 2006;Zhang et al., 2016;Zhao et al., 2013;Ž igaitė et al., 2020). In fact, in view of the short lifespan of an organism compared to geological times, it is during diagenesis that bioapatite is most chemically modified (Chen et al., 2015;Kim et al., 2012;Lécuyer et al., 2004;Trotter et al., 2016;Zhang et al., 2016) and a frank estimation of REE sources can be based, for example, on the analysis of specific relationships between the sum of all REE (ΣREE), light REE (LREE), middle REE (MREE), heavy REE (HREE) and the content of Y and Ho (Chen et al., 2015;Grandjean-Lécuyer et al., 1993;Lécuyer et al., 2004;Li et al., 2017;Nothdurft et al., 2004;Nozaki et al., 1997;Pattan et al., 2005;Peppe and Reiners, 2007;Shen et al., 2012;Webb et al., 2009;Webb and Kamber, 2000;Wright et al., 1987;Wright and Colling, 1995;Zhang et al., 1994Zhang et al., , 2016Zhang and Nozaki, 1996). Some studies have considered the influence on fossil chemical compositions of the depositional environment with respect to diet or physiology of vertebrates, underlying that they are variously affected by the stages of diagenesis. ...
... The Y/Ho ratio (Y/Ho = 28.8) deviates from the chondritic value (Zhang et al., 1994;Bau, 1996). Highly desilicified episyenite samples have a Y/Ho value slightly higher than the chondritic value. ...
Kab Amiri granites are submitted to post-magmatic hydrothermal solutions through fracture and faults, causing several alteration processes. The most common processes are episyenitization, saussuritization, hematitization, sericitization, kaolinization, albitization, chloritization, silicification, and muscovitization. Kab Amiri granites are vuggy, with the vugs partially to completely refilled with new constituents. The least episyenitized granites have elevated amounts of Fe, P, Zr, Ni, U, Th, Ba, Y, Hf, Nb, and As, which are correlated with their mobilization from biotite, k-feldspar, plagioclase and metamict zircon. These elemental changes are related the partial albitization, muscovitization, desilicification and chloritizatiom, which lead to the mobilization of these elements and forming of specific mineral association in the least altered granites such as autonite, tripiolite, columbite, Zircon and galena. On the second stage, granites were subjected to intense alteration processes by mineralizing fluids, causing wholly muscovitization of biotite and feldspar, albitization of plagioclase, carbonitization and apatitization. Many elements were mobilized from these altered minerals, including Ti, Al, Mn, Mg, Ca, Na, K, Mo, Cu, Pb, Zn, Ag, Co, Sr, V, Cr, Sn, Rb, Ta, Li, Sc, W, S, In, and Tl, leading to definite mineralization as kaslite, monazite, xenotime, polycrase and apatite. The mineralizing fluids in the least and highly episyenitized granites are incorporated in some ore minerals like uranophane, fergusonite, bazzite and garnet. Notably, the presence of elements such as U, Th, and other heavy metals in Kab Amiri granites highlights the potential for these rocks in radiation shielding applications. The unique combination of elements and minerals resulting from the alteration processes can be leveraged for developing new materials or enhancing existing materials used in radiation shielding.
... Among the analyzed trace elements, the Y content in shells is scarcely studied and it is usually interpreted together with REE (Ponnurangam et al., 2016;Valdés-Vilchis et al., 2021); its behavior is similar to that of holmium given the similar ionic radii, identical charge, and similar stability for carbonate complexation in seawater (Zhang et al., 1994;Smrzka et al., 2019). Yttrium presents the highest average concentrations in high-Mg calcitic shells of bryozoans and echinoids and aragonitic microbaciid corals, whereas the lowest concentrations are found in aragonitic mollusc shells and the low-Mg calcite of brachiopods (Fig. 5). ...
... The positive La and Gd anomalies in the carbonate samples may be due to their lower ability to complex with carbonate in solution and particulate matter, respectively. The super-chondritic Y/Ho ratios could be either the result of differences in the two element's ability to complex with carbonate in solution or differences in scavenging processes by particulate matter resulting in preferential removal of Ho upon delivery to the ocean (Zhang et al., 1994;Nozaki et al., 1997). Although the slope of the REE curves is less for the Red Lake-Wallace Lake chemical sediments, these trends are similar to average modern sea water. ...
... (1) ray-Darling basin) [45] ，同时考虑地理位置，本文也比较 Hf/ (mg·kg −1 ) 0 Mid-ocean ridge basalt data refer to reference [54]; Australian wind-dust sediment data refer to reference [55]; pore water data refer to reference [56]; seawater data refer to reference [57]; hydrothermal data refer to reference [58]; NASC data refer to reference [37] 成岩微结核的REY，比较了NASC标准化配分模式 (图14 Picture on a refer to reference [72], the dotted present the mixing trends between two genetic processes highlighting the continuum existing between hydrogenetic-hydrothermal crusts and hydrogenetic-diagenetic nodules, solid arrows show evolution trends of a sample set related to only one genetic process without influence of another one; picture on b refer to reference [73] La ...
In this paper, sediment smear observations, X-ray diffraction analyses, major, trace and rare earth elements
analyses, and in situ micro zone geochemical analyses of single minerals were carried out on samples of core
GC02 and GC06 from the rare earth-rich deep-sea sediments in the Central Indian Ocean Basin to explore their geochemical
characteristics, material sources and enrichment mechanisms of rare earth elements (REY). The results
show that the sediment types of core GC02 are calcareous clay and zeolitic clay, and the sediment types of core
GC06 are calcareous clay, zeolite-bearing clay and zeolitic clay. Rare earth elements are enriched in zeolite-bearing
clays and zeolitic clays. The North American Shale Composite (NASC) Standardized patterns of REY in the
sediments indicate a possible seawater origin. Mineralogical and geochemical signatures indicate that the terrestrial
fraction of these sediments in the study area should be the eolian dust material originated primarily from Australian.
Elemental correlations and CaO/P2O5 ratios indicate that the main host mineral of REY in REY-rich deep-sea sediments
is bioapatite (fish teeth/bone), followed by Fe-Mn micronodule. This study summarizes and discusses the
formation mechanism of REY-rich sediments and improves a conceptual model for the formation process of REY-
rich sediments.
... Y content values can be used to assess post-deposition changes during fluid circulation [81]. These values show positive anomalies in seawater and are not affected by redox conditions, but the magnitude of these anomalies may decrease under diagenetic effects [68,74,81,82]. Kechiched et al. [20] suggested that the southern Algerian phosphates have low Y/Y* ratios and, therefore, that they reflect slight early diagenesis. ...
The Tethyan phosphates were formed during the Upper Cretaceous and Eocene interval as a result of the collision of the African–Arabian and Eurasian plates and the closing of the Neo-Tethys Ocean. This study aimed to reveal the possible precipitation parameters of these phosphates by examining the main oxide, trace and rare earth element contents of the phosphates in the study region. The mean major oxide concentrations of the phosphates were found to be 51.6 wt.% CaO, 21.2 wt.% P2O5, 8.03 wt.% SiO2, 18.1 wt.% CO2, 0.51 wt.% K2O, 0.12 wt% Fe2O3, 0.05 wt% Al2O3, 0.18 wt% MgO and 0.02 wt.% MnO. The average trace element concentrations were 79 ppm Ba, 1087 ppm Sr, 0.23 ppm Rb, 14.7 ppm Ni, 108 ppm Cr, 262 ppm Zn, 27 ppm Cd, 21.6 ppm Y, 58 ppm V, 6.43 ppm As, 30.3 ppm Cu, 1.36 ppm Pb, 6.32 ppm Zr, 39 ppm U, 0.21 ppm Th and 1.33 ppm Co. The average trace element contents were 1742 ppm, with this indicating an enrichment assemblage of Sr, Cd, As, and Zn in comparison to PAAS (The Post-Archean Australian Shale). The total REE concentrations in the Mazıdağı phosphates varied from 3.30 to 43.1 ppm, with a mean of 22.1 ppm recorded. All phosphates showed heavy REE (HREE) enrichments and had similar REE patterns to PAAS. All samples had strongly negative Ce and positive Eu, Pr and Y anomalies. These anomalies indicate the existence of oxic and suboxic marine conditions during the formation of the phosphates. According to the proposed genetic model, the phosphates mostly formed in oxic and suboxic zones of the Tethys Ocean and were precipitated on slopes that depended on strong upwelling from an organic-rich basin in anoxic/suboxic conditions from deeper seawater. The Pb isotope data obtained also indicate the existence of a deep-sea hydrothermal contribution to this phosphate formation.
... Seawater (e.g. natural low-temperature aqueous solution) is characterized by Y/Ho ratios between 44 and 74 and by Zr/Hf ratios between 85 and 130 (Zhang et al. 1994;. The Zr/Hf ratio is considerably higher than those values suggested by Boswell & Elderfield (1988). ...
Organic carbon and nitrogen fixed in illite (I) clays were identified in a hydrothermal breccia structure from the Harghita Bãi area of the Neogene volcanism of the East Carpathians. The potassium-illite (K-I) alteration related to an early magmatic-hydrothermal event (9.5 ± 0.5 Ma) was later replaced by ammonium-illite (NH 4 -I) (6.2 ± 0.6 Ma) owing to circulation of an organic-rich fluid. Several textural evolutions of breccia structures were recognized, such as ‘shingle’, ‘jigsaw’, ‘crackle’ and hydraulic in situ fractures. The high-field-strength element behaviours of the K-I and NH 4 -I argillic altered andesite are close to chondritic ratios, indicating no contribution of hydrothermal fluid, especially on NH 4 -I andesite alteration and the CHArge-and-RAdius-Controlled (CHARAC) behaviour within silicate melts. The rare earth element normalized patterns show two distinct trends, one with a Eu* anomaly (K-I) and the other with a Nd* anomaly (NH 4 -I), indicating a boundary exchange with the organic-rich fluid. The strongly depleted δ ¹³ C (V-PDB) measured for the NH 4 -I clays reflects values (−24.39 to −26.67 ‰) close to CH 4 thermogenic oxidation, whereas the δ ¹⁵ N (‰) from 4.8 to 14.8 (± 0.6) confirmed that the N 2 originated from post-mature sedimentary organic matter. The last volcanism (6.3 to 3.9 ± 0.6 Ma) and simultaneous volcano-induced tectonics in the proximity of the eastern Transylvanian basin basement increased the heat flow, generating lateral salt extrusion, diapirism and increased pressure in the gas reservoir. New pathways were opened that provided new circulation routes for basinal fluids to new and old permeable zones and expelled seeps from the biogenic petroleum system.
... This means that the Y/Ho ratio can reflect the physicochemical conditions of the depositional environment. The chondritic value (Y/Ho = 28.8) is recorded for samples didn't affected by hydrothermal alteration where deviation of Y/Ho ratio from the chondritic values is only related to samples showing a tetrad effect (Zhang et al., 1994). The studied samples have Y/Ho ratios lower than the Chondritic value, one sample has chondritic ratio (sample S9), (Table 4). ...
... The ratio of Y/Ho can also applied to evaluate the role of alteration. This ratio is 28 in fresh mafic rocks and ranges between 44 and 47 in altered rocks (Zhang et al., 1994;Bau, 1996). The Y/Ho ratio for studied rocks varies from 23 to 30, representing that the secondary process were not significant factor in this area. ...
Geodynamically, the Kashmar-Kerman Tectonic Zone (KKTZ) is one of the most perplexing tectonomagmatic belts of the Central Iran Microcontinent (CIM), comprising two important districts, Bafq and Kuh-e-Sarhangi. The Late Neoproterozoic-Early Cambrian granitoids, metamorphic rocks, and mildly metamorphosed volcansedimen-tary sequences are the oldest geologic outcrops in the Narm area, which is located in the western part of Kuh-e-Sarhangi. Alkaline gabbro-diorites with relatively high contents of K 2 O (1.99-3.03 wt%) and Na 2 O (2.7-5.99 wt%) are among the youngest intrusive rocks in the area, representing a within-plate provenience. These rocks were emplaced into Paleozoic sedimentary units as mafic-intermediate stocks, sills and dykes. Geo-chemically, these rocks could have resulted directly from partial melting (e.g., FeOT/MgO>1, Nb/La>0.5) with no considerable indication of assimilation with crustal materials (e.g., Ti/Zr > 30, Ti/Y > 200). Assimilation and fractional crystallization cannot account for magma evolution of gabbro-diorite rocks in the Narm area, using rare earth element ratios and geochemical models. There are also some geochemical signatures of an as-thenospheric origin for the Narm gabbro-diorite rocks, such as the low ratios of La/Nb (1.5) and La/Ta (22). U-Pb zircon ages show that the Narm gabbro-diorites formed during two major episodes of magmatism in Central Iran: 40.3 ± 0.1 Ma in the Late Eocene (Bartonian) for gabbroic units and 8.04 ± 0.05 and 7.86 ± 0.05 in the late Miocene (Tartonian) for diorite stocks and diorite sills, respectively. Despite a time difference of more than thirty million years, geochemical similarities between the Eocene gabbro rocks and the Miocene diorite from the Narm area are striking. It is proposed that the best scenarios for the west of Kuh-e-Sarhangi mafic-intermediate magmatic pulses along with the deep faults of the Central Iran, are an Eocene magmatic flare up and a Miocene asthenosphere upwelling. Temporally and spatially, these rocks are comparable to the Cenozoic alkaline intrusive rocks of the Bafq region.
... The ratio of Y/Ho can also applied to evaluate the role of alteration. This ratio is 28 in fresh mafic rocks and ranges between 44 and 47 in altered rocks (Zhang et al., 1994;Bau, 1996). The Y/Ho ratio for studied rocks varies from 23 to 30, representing that the secondary process were not significant factor in this area. ...
Geodynamically, the Kashmar-Kerman Tectonic Zone (KKTZ) is one of the most perplexing tectonomagmatic belts of the Central Iran Microcontinent (CIM), comprising two important districts, Bafq and Kuh-e-Sarhangi. The Late Neoproterozoic-Early Cambrian granitoids, metamorphic rocks, and mildly metamorphosed volcansedimentary sequences are the oldest geologic outcrops in the Narm area, which is located in the western part of Kuh-e-Sarhangi. Alkaline gabbro-diorites with relatively high contents of K2O (1.99–3.03 wt%) and Na2O (2.7–5.99 wt%) are among the youngest intrusive rocks in the area, representing a within-plate provenience. These rocks were emplaced into Paleozoic sedimentary units as mafic-intermediate stocks, sills and dykes. Geochemically, these rocks could have resulted directly from partial melting (e.g., FeOT/MgO>1, Nb/La>0.5) with no considerable indication of assimilation with crustal materials (e.g., Ti/Zr > 30, Ti/Y > 200). Assimilation and fractional crystallization cannot account for magma evolution of gabbro-diorite rocks in the Narm area, using rare earth element ratios and geochemical models. There are also some geochemical signatures of an asthenospheric origin for the Narm gabbro-diorite rocks, such as the low ratios of La/Nb (1.5) and La/Ta (22). U–Pb zircon ages show that the Narm gabbro-diorites formed during two major episodes of magmatism in Central Iran: 40.3 ± 0.1 Ma in the Late Eocene (Bartonian) for gabbroic units and 8.04 ± 0.05 and 7.86 ± 0.05 in the late Miocene (Tartonian) for diorite stocks and diorite sills, respectively. Despite a time difference of more than thirty million years, geochemical similarities between the Eocene gabbro rocks and the Miocene diorite from the Narm area are striking. It is proposed that the best scenarios for the west of Kuh-e-Sarhangi mafic-intermediate magmatic pulses along with the deep faults of the Central Iran, are an Eocene magmatic flare up and a Miocene asthenosphere upwelling. Temporally and spatially, these rocks are comparable to the Cenozoic alkaline intrusive rocks of the Bafq region.
... Furthermore, the (Y/Y*) versus (La/Nd) N ratios (Fig. 10B), although not affected by redox conditions, may decrease during diagenesis and can be used to track the post-depositional changes, such as fluid circulation in the burial environment (Zhang et al., 1994;Bau, 1996;Shields and Stille, 2001;Fazio et al., 2007). All grain size fractions show similar values of Y/Y* and (La/Nd) N within the same sample and mostly are in the seawater range except the Kef Essenoun upper sub-layer phosphorites that yielded higher (Y/Y*) and (La/Nd) N values. ...
Rare earth elements and yttrium (REY) have gained greater attention for being largely used in various high-tech applications and green energies. Recently, supply shortage and high demand on REY led to target secondary resources such as phosphorites. Algerian sedimentary phosphorites, which are located mainly in the Tébessa region, Eastern Saharan Atlas, are relatively enriched in REY according to recent whole-rock analyses. The aim of this study is to explore variation of REY contents and other geochemical features with respect to particle size fractions. In addition, the economic significance of the P-deposits was assessed using new indicators, such as the outlook coefficient of REY composition (Coutl) and the percentage of critical element in total ΣREY (REYdef). Three friable whole-rock samples from two P-deposits (Djebel El Kouif and Kef Essenoun) were sieved and retained fractions (f) of <45 μm, 45–125 μm, 125–250 μm, 250–500 μm and >500 μm were analyzed for their major and REY contents using ICP-MS techniques. Principal Component Analysis (PCA) was applied on centred log-transformation (clr) data, which are adapted to such compositional dataset, as well as Variance Analysis (one-way ANOVA) technique. The results show that the samples yield P2O5 grades ranging from 20 to 36 wt% and total REY contents in selected 15 samples vary in the considered grain size fractions as follows: f<45μm = 325 ppm–719 ppm; f45–125μm = 309 ppm–893 ppm; f125–250μm = 314 ppm–1029 ppm, f250–500μm = 354 ppm–809 ppm, f>500μm = 308 ppm–652 ppm. The one-way ANOVA reveals that there is no significant difference of REY concentrations between the grain size fractions. However, the REY grades strongly based on both the studied deposits and the stratigraphic position of the hosting samples (p-value ≤ 0.01); this is also confirmed by PCA. REY geochemical signatures (normalized REY distribution patterns and Ce, Eu, and Y anomalies) are similar in the grain size fractions from the same hosting samples indicating synchronized evolution of all rock components, where REY distribution is mostly controlled by the depositional environment, irrespective of grain size in the rock. The Coutl coefficient shows values between 1.89 and 6.85 and REYdef varies from 47.44 % to 64.90 %. However, the upper sub-layer of Kef Essenoun phosphorites that yielded the lowest ∑REY contents, shows markedly the highest Coutl (6.61–6.85) and REYdef (64.31–64.90), pointing to more promising source for extracting individual critical REY elements, even in low P-grade phosphorite ores.
... The Y anomaly and LaN/NdN ratio are considered useful indicators for determining the post-depositional changes related to variations in the composition of circulating fluids [85]. These two parameters have positive anomalies in modern seawater [44,86]. Although they are not affected by environmental redox changes, diagenetic processes can have great influence on them [33]. ...
The rare earth elements and yttrium (REY)-enriched phosphorites in the Zhijin region, southwest China, have attracted much attention, yet its origin has not been sufficiently addressed. The geology, mineralogy and geochemistry of samples from four sections of the early Cambrian age from the Zhijin region were studied to attain the redox condition and origin of REY. Data from in situ analysis show that REY are mainly contained in francolite, and the two types of francolite (bioclastic and granular) have no distinct difference in REY content (ΣREY). A Ce anomaly indicates an oxic condition in primary seawater. An Eu anomaly and ratios of redox sensitive elements (RSEs) indicate a fluctuating redox condition during phosphorite deposition. Shale-normalized REY patterns of whole rock and francolite show a hat-shaped pattern, indicating the effect of diagenetic processes. The Y/Ho ratio of the selected sections ranges from 38.13 to 61.93, and together with the Y anomaly, LaN/NdN ratio, LaN/SmN ratio, and LaN/YbN ratio, this indicates a seawater origin. This is supported by the Ce/Ce* of the phosphorite that ranges from 0.32 to 0.52 and the Eu/Eu* that ranges from 0.88 to 1.82, which is similar to the characteristics of seawater and deep-sea mud. We also propose a minor contribution of terrigenous debris and influence of diagenesis and hydrothermal processes.
... Here we rely on a large body of experimental data that now exists for Y + REE partitioning between ferrihydrite and fluid, which allows calculation of fluid compositions based on measured jaspilite compositions if some assumptions may be made regarding fluid composition. In addition to determining broad characteristics of REE patterns such as LREE/HREE ratios, it has been long recognized that fluid-particle interactions are key in determining anomalous behavior for some REEs that exhibit "tetrad" effects such as La, Gd, and Lu, as well as Y/Ho fractionation (e.g., Byrne and Lee, 1993;Liu et al., 1993;Zhang et al., 1994;Bau et al., 1995Bau et al., , 1997Bau, 1999). These features have been shown to be recorded in Precambrian iron formations and jaspilites (e. g., Bau and Dulski, 1996;Minami et al., 1998), highlighting the potential to determine Y + REE characteristics and fractionation processes of ancient fluids using iron oxide-bearing lithologies. ...
The chemical and isotopic compositions of Precambrian Fe-rich chemical sedimentary rocks have figured prominently in discussions on the Fe biogeochemical cycle and redox conditions in the early Earth. Broad trends of decreasing δ⁵⁶Fe values for Eoarchean to Paleoproterozoic iron formations (IFs) and jaspilites (hematite-chert) with decreasing age reflect a general increase in extent of oxidation of aqueous Fe(II) (Fe(II)aq) in marine environments, consistent with increasing oxygenation of surface environments, particularly since the Mesoarchean. Such trends may record a shift from anaerobic to aerobic oxidation, in part reflecting increasing nutrient abundances that follow increased emergence of continental crust. It is commonly proposed that the size of the biosphere in the early Archean was largely nutrient limited, specifically P limited. Highly positive δ⁵⁶Fe values for Fe oxides in chemical sedimentary rocks deposited in open marine environments at this time are consistent with excess Fe(II)aq.
Here, we present new data on Fe isotopes and trace element chemistry for 3.4–3.5 Ga jaspilites from the North Pole region of the Pilbara Craton, including the first example of a land-sea transition preserved in the lower Dresser Formation as jaspilite deposition in restricted basin and open-marine settings. A review of the possible mechanisms of Fe(II)aq oxidation in the early Archean - including O2 generated by oxygenic photosynthesis, UV photo-oxidation, or photoferrotrophy (anoxygenic photosynthesis) - suggests that the latter is most likely, in light of evidence for low-O2 contents and the strong role that silica plays in inhibiting abiologic Fe(II) oxidation. Y + REE contents of lower Dresser Formation jaspilites indicate a freshwater component in the restricted basin settings, in contrast to exclusively seawater components in the open-marine environments. δ⁵⁶Fe values for open-marine jaspilites are highly positive.
(δ⁵⁶Fe ~ +1 to +2.4‰), similar to other jaspilites and IFs of Eoarchean to Paleoarchean age. Assuming photoferrotrophy as the oxidative pathway, this would indicate electron donor (Fe(II)aq) excess and nutrient limitation. For the restricted-basin jaspilites of the lower Dresser Formation, δ⁵⁶Fe values extend to slightly negative values (δ⁵⁶Fe ~ −0.4‰), correlating with changes in Y + REE contents that indicate fluid mixing. In toto, there is a range of ~3‰ in δ⁵⁶Fe values across the land-sea transition of the lower Dresser Formation, significantly exceeding the range previously measured in early Archean jaspilites. Combined with an advection-dispersion-reaction model for Fe(II)aq oxidation via photoferrotrophy, these observations suggest a range of nutrient abundance with environment, where samples from near-shore or restricted settings record excess nutrients from terrestrial input and hence electron donor limitation.
Integrating the new results from the Pilbara Craton with the broader Fe isotope database for Eoarchean through Paleoarchean jaspilites and IFs, as well as a simple mass-balance model relating δ⁵⁶Fe values and P contents, it becomes apparent that the relatively high nutrient abundance seen only in restricted settings at ~3.5 Ga becomes more characteristic of the open oceans by ~3.2 Ga. This expansion of nutrient availability is correlated with a marked increase in ⁸⁷Sr/⁸⁶Sr ratios for seawater, which can be shown to be a proxy for P delivery to the open oceans from the continents via weathering fluxes. Collectively, these findings demonstrate the importance of considering geologic context in interpreting Fe isotope and chemical compositions of jaspilites and IFs. Capture of the land-sea transition of the lower Dresser Formation provides insights into the biosphere that would have been missed in sample suites that only record open-marine conditions.
... Y and Ho generally act as geochemical twins because they have very similar ionic radii and identical valences (Zhang et al., 1994;Pack et al., 2007). Therefore, Y and Ho are tightly coupled in many geological processes such as magmatic and hydrothermal activity, which generally maintains chondritic Y/Ho ratios ($25-30; Pack et al., 2007). ...
Rare earth elements and Yttrium (REYs) are critical to the emerging high-tech and green-energy industries, generating tremendous REY demand in recent decades. Recently, many sedimentary phosphorites have been reported to have extraordinary REY enrichment (> 1000 ppm) and may become new REY resources. However, the controls of REY enrichment in phosphorites have not been well constrained. To better understand the discrepant REY enrichment in phosphorites, the early Cambrian high-REY Zhijin (ZJ) phosphorites (∼500–2000 ppm) and the relatively low-REY Meishucun (MSC, ∼200–400 ppm) and Xia’an (X’A, mostly < 200 ppm) phosphorites on the Yangtze Block of South China were investigated with mineralogy, bulk-rock elements, total organic carbon, in-situ elements, and Zn-Fe isotopes. The mineral characteristics, REY indexes, and in-situ REY mapping indicate that the X’A phosphorites may represent pristine phosphorites, whereas the ZJ and MSC phosphorites may have experienced intensive diagenetic alteration. Diagenetic alteration can only explain the REY enrichment in the MSC phosphorites compared to the pristine X’A phosphorites, but it does not sufficiently explain the extraordinary REY enrichment in the ZJ phosphorites. Additionally, the lower δ⁶⁶Zn values of the ZJ and X’A phosphorites (δ⁶⁶Znaverage = 0.16‰ and 0.14‰, respectively) than those of the MSC phosphorites (δ⁶⁶Znaverage = 0.75‰) indicate higher productivity levels in the ZJ and X’A areas. However, the high-productivity X’A phosphorites yielded very low REY concentrations, indicating that the extraordinary REY enrichment in the ZJ phosphorites cannot be ascribed to high productivity levels. Notably, the ZJ phosphorites may have experienced more intensive Fe redox cycling under fluctuating oxic–suboxic deposition conditions (∼0.0‰–0.45‰ δ⁵⁶Fe values in near-pure phosphorites) than the MSC and X’A phosphorites with completely oxic deposition conditions (∼0.0‰ δ⁵⁶Fe values). Frequent Fe redox cycling can greatly enrich REYs in porewater, which can be subsequently transferred into francolites during its formation and early diagenesis. Therefore, frequent Fe redox cycling driven by fluctuating oxic–suboxic seawater conditions may be responsible for the extraordinary REY enrichment in the ZJ phosphorites. If this is the case, we propose that phosphorites deposited near the oxic–suboxic redox chemocline are favorable for extraordinary REY enrichment, such as the coeval near-slope phosphate concretions on the Yangtze Block and other phosphorites or phosphatic rocks formed in different basins at different geological times.
... Furthermore, Y/Ho ratios have been used as an indicator of alteration. The ratio is from 44 to 74 and 28 in altered (Zhang et al. 1994;Bau et al. 1995) and fresh rocks (Bau 1996), respectively. The Y/Ho ratios in the OSRs and KSRs range from 25 to 27, suggesting no involvement of secondary processes in the samples. ...
Tertiary subvolcanic basic rocks are found as sills, dykes, and stocks in the southern flanks of the Central Alborz Magmatic Belt, north of Tehran. The rocks can be divided into two subvolcanic rock groups based on their geographic locations: (1) the western Kiga group and (2) an eastern group. The eastern group range from micromonzogabbro/diorite to microgabbro, whereas the Kiga group consists of micromozodiorite to micromonzogabbro. Mineral compositions, whole-rock major and trace elements show that these rocks have calc-alkaline affinities. The eastern group extends to higher MgO (4–10wt%) than the Kiga group (MgO= 4–5 wt%). With decreasing MgO, the contents of SiO2, TiO2, Al2O3, Na2O, and P2O5 increase and the contents of CaO and compatible trace elements (e.g., Co, Ni, Cr) decrease, consistent with olivine and clinopyroxene fractionation. At a given MgO, the Kiga rocks have higher FeOt, K2O, and P2O5 and extend to higher overall highly to moderately incompatible elements (Rb, Ba, Th, U, Nb, Ta, LREE, Sr, and Zr) and lower Al2O3 and Na2O. The depletion in Nb and Ta but enrichments in Rb, Ba, Th, U, K, Pb, and Sr, compared to N-MORB as well as high Th/Yb (at a given Nb/Yb or Ta/Yb), indicates a subduction zone origin for both subvolcanic groups of rocks. The initial Sr and Nd isotopic ratios of the subvolcanic rocks vary from 0.7048 to 0.7064 and 0.5126 to 0.5128, respectively. Furthermore, εNd (50 Ma) values (+0.64 to +5.19) associated with the two-stage model ages (0.42 to 0.78 Ga) of the samples infer a contribution of Cadomian-enriched lithospheric mantle in their source for this melt. The most evolved sample from the Kiga group has the lowest 143Nd/144Nd and highest 206Pb/204Pb and 208Pb/204Pb ratios. The isotope correlations could be explained by upper crustal assimilation/contamination by the more evolved samples or reflect source differences (i.e., higher amount of subducted sediments) in the Kiga source. In conclusion, we interpret that the subvolcanic rocks have formed in an active continental margin.
... The different nature and stability of the complexes formed, along the whole series, could induce fractionations among the REE (Lee and Byrne, 1992;Byrne and Li, 1995), because of the competing affinity of REE for dissolved and surface complexes. The REE pattern of ASW (Fig. 6a), which is consistent with that expected for modern seawater, results from both complexation, operated by the carbonate ions, and scavenging on particles (Byrne and Kim, 1990;Zhang et al., 1994;Byrne and Sholkovitz, 1996;Nozaki et al., 1997;Alibo and Nozaki, 1999;Bau, 1999;Bolhar et al., 2004;Johannesson et al., 2006;Planavsky et al., 2010;Kamber et al., 2014;Wang et al., 2016). The carbonate complexes dominate the inorganic REE speciation in seawater, as mono-carbonate [REECO 3 ] + at pH values between 6 and 8 (Appendix B), and/or di-carbonate [REECO 3 ] 2 − complexes at pH above 8 (Byrne and Sholkovitz, 1996;Ohta and Kawabe, 2000a;Luo and Byrne, 2004). ...
Trace metals and Rare Earth Element (REE) are amply discharged by submarine hydrothermal vents, sometimes leading to the formation of ore deposits of economic interest. We report on first data on the geochemical processes involving REE and trace metals, at the solid-liquid interface, in the hydrothermal area of Levante Bay at Vulcano Island (Aeolian Archipelago, Italy). Samples were collected from several submarine springs and seeps, small mud pools and one thermal well, and analyzed for Al, Si, Ti, V, Cr, Mn, Fe, Co, As, Rb, Sr, Cs, Ba, U and REE, besides major ions.
Within the bay, hydrothermal fluids contaminate seawater and promote the leaching of metals from sediments through the dissolution of CO2 and H2S, while the particulate matter removes several elements from the water. The leaching of the bottom sediments and the contribution of steam-heated water produce an enrichment of some metals and REE in the Levante Bay with respect to the concentrations expected in the ambient seawater. An enrichment up to one order of magnitude is measured for Fe, Al, Ba, Cs and Rb, and up to two orders of magnitude for Mn in the submarine samples. Other transition metals (Ti, V, Co, Cr), U, As and Sr have concentrations similar or slightly lower than the ambient seawater. REE are in concentrations higher than in ambient seawater up to two orders of magnitude. Despite being significantly higher than uncontaminated seawater, the concentrations of some metals (namely Fe, Al, Ti, Cr, V, Co, U) and REE in most samples are lower than expected by the mixing between seawater and the steam-heated water, discharging from submarine springs. Indeed, equilibrium and reaction path modeling indicate the likely precipitation of Fe-oxyhydroxides, able to remove minor elements, such as Ti, Cr, Co, V and As, and REE. The last ones are significantly removed by newly-forming solid phases, due to the presence of a large amount of Fe released by the acidic fluids through the leaching of sediments. The low pH limits the formation of solution complexes of REE with carbonate ions (the main complexing agent for REE in seawater), whereas the sorption onto particles is still effective, even at close distance from the submarine springs and seeps.
This study brings new insights on the geochemical processes occurring in submarine hydrothermal systems, in particular, those in subduction-related context.
... Interpretation of the presence or lack of a Ce anomaly is often complex due to the anomalous behaviour of La (Bau & Dulski, 1996). Earlier studies Bolhar & Kranendonk, 2007;Zhang et al., 1994) indicate that modern seawater shows characteristics of positive La, Y, Gd and negative Ce anomalies, LREE depletion, HREE enrichment and also hydrothermal Fe-Mn sediments on oceanic crust. The Cihanpaşa Fe-Mn ore samples reflect positive La and pronounced negative Ce anomalies ( Figure 6a). ...
Fe-Mn-oxide (oxyhydroxide) deposits are common within the late Cretaceous mélange units of the İzmir-Ankara-Erzincan Suture Zone, which marks the closure of part of the northern branch of the Neotethys Ocean in Turkey. In the Cihanpaşa region (Yozgat, central Turkey), Fe-Mn mineralisation occurs as interlayers within a sequence of mudstone and siliceous pelagic units that overlies altered pillow lavas belonging to the Artova ophiolitic complex. T-Fe-Mn mineralisations are characterised by moderate amounts of Ba (560 ppm), and low contents of Sr (243 ppm), Co (51 ppm), Zn (183 ppm), and Ni (221 ppm). Mn/Fe (0.69) and low Co/Ni (<0.40), Co/Zn (<0.50) and Y/Ho (25.7) ratios and ΣREE (233) values suggest that mineralisation formed in a submarine environment hydrothermal system. The low Ceanom. values (−0.60) are consistent with a mostly oxic depositional environment. Further, low LaSN/NdSN (<1), negative Ce anomaly (0.29), and low Al/(Al+Fe) (0.14), whereas high LaSN/CeSN (4.01) and Fe/Ti ratio (208) with moderately positive Eu anomaly (1.22), and Ti/V (1.99), LuSN/LaSN (0.89), ΣREE/Fe ratio (22.36 × 10–4) indicate that the Cihanpaşa Fe-Mn mineralisation formed in an oxygenised marine sedimentary environment with influence of a ridge-proximal (near spreading ridge) submarine hydrothermal vent system in the İzmir-Ankara-Erzincan Neotethyan Ocean. These results indicate that detailed geological and geochemical evidences determined in silicilastic rocks and submarine volcanics within mélange associations well-exposed along the suture belt could be applied to exploration studies for the discovery of ancient submarine deposits, including significant and precious metals such as polymetallic Fe-Mn deposits (Fe-Mn crust and nodules) and seafloor sulphide mineralisation.
... Yttrium and Ho exhibit similar geochemical behavior, although Ho is preferentially complexed and removed from fluids by Fe-oxides and organic particles; consequently, seawater and seawater-derived fluids preserve super-chondritic (>28) Y/Ho values, whereas crustal fluids have chondritic Y/ Ho values (Zhang et al. 1994;Nozaki et al. 1997;Bau and Dulski 1999). Similarly, there are subtle differences in the adsorption of LREE, MREE, HREE, and Ce onto organic particles, oxide phases, or mineral phases (e.g., German and Elderfield 1989;Sholkovitz et al. 1994;Alibo and Nozaki 1999). ...
Carbonate minerals are ubiquitous in most sediment-hosted mineral deposits. These deposits can contain a variety of carbonate types with complex paragenetic relationships. When normalized to chondritic values (CN), rare-earth elements and yttrium (REE+Y CN ) can be used to constrain fluid chemistry and fluid-rock interaction processes in both low- and high-temperature settings. Unlike other phases (e.g., pyrite), the application of in situ laser ablation-inductively coupled plasma-mass spectroscopy (LA-ICP-MS) data to the differentiation of pre-ore and hydrothermal carbonates remains relatively untested. To assess the potential applicability of carbonate in situ REE+Y data, we combined transmitted light and cathodoluminescence (CL) petrography with LA-ICP-MS analysis of carbonate mineral phases from (1) the Proterozoic George Fisher clastic dominated (CD-type) massive sulfide deposit and from (2) correlative, barren host rock lithologies (Urquhart Shale Formation). The REE+Y CN composition of pre-ore calcite suggests it formed during diagenesis from diagenetic pore fluids derived from ferruginous, anoxic seawater. Hydrothermal and hydrothermally altered calcite and dolomite from George Fisher is generally more LREE depleted than the pre-ore calcite, whole-rock REE concentrations, and shale reference values. We suggest this is the result of hydrothermal alteration by saline Cl ⁻ -rich mineralizing fluids. Furthermore, the presence of both positive and negative Eu/Eu * values in calcite and dolomite indicates that the mineralizing fluids were relatively hot (>250°C) and cooled below 200–250°C during ore formation. This study confirms the hypothesis that in situ REE+Y data can be used to differentiate between pre-ore and hydrothermal carbonate and provide important constraints on the conditions of ore formation.
... The Y/Ho ratio is commonly used as a proxy to indicate terrestrial contribution to the sediments because Y behaves in accord with Ho and no fractionation between the two elements occurs during terrestrial processes. Although these elements have similar ionic radii, Y distinctly deviates from Ho due to the competitive reactions during scavenging by marine particulate matter (Zhang et al., 1994;Nozaki et al., 1997;Bau, 1999). The low Y/Ho ratios of the Cherai sediments (on average 10.22), below the chondritic ratio, indicate a relatively more minor contribution of terrestrial detritus. ...
Climate changes on the Southwest coast of India have essential impacts on social and economic development, and the ecosystem of Southern India. Here, we present the last 2000 cal yr AD rare earth elemental records of the sediment core from the Cherai, Kerala coast, southwest India. The light rare earth elements (LREE) were the most abundant fraction in the core sediment, followed by medium rare earth elements (MREE) and heavy rare earth elements (HREE). Total REE (RREE) showed a significant correlation with fine fractions and Y, Al, Ti, Fe and total organic carbon content of the sediments, suggesting an intrinsic relationship between REE, total organic carbon and fine grain-size fraction. The LREE and MREE were enriched over the MREE due to their high adsorption with the fine fraction. The lack of correlation between terrigenous elements and low Y/Ho elemental ratio suggests a minor shift in the source materials. High RREE values during warm (Medieval Warm Period/Medieval Climate Anomaly (MWP/MCA) and cold Little Ice Age (LIA) periods indicate a high influx of lithogenous materials during these intervals. The negative dCe values except MCA suggest a suboxic condition and the dEu values suggest feldspar-rich source rock material derived from moderately weathered sediments. It also indicates that the REE variations are controlled by factors like river supply, biological productivity and redox condition. A close link between monsoonal precipitation and REE records existed on the southwest coast of India. During the Dark Age Cold Period (DACP)/MWP transition, a sudden increase in monsoon is documented and the monsoon precipitation was further decreased during LIA and Current Warming Period. The Cherai core REE records synchronize with the episodes of centennial-scale warm/cool events and essentially follow the northern hemispheric climate cycles.
... The distribution patterns of rare earth elements and Y in the complete section of Enshi stone coals (Figure 9; 6.12 m in total thickness, 30 bench samples; the stone coal section presented in Figure 1(b); concentrations of rare earth elements and Y are listed in the Supplementary Electron Table) are characterized by positive Y and Gd, weakly negative Ce and Eu anomalies, and heavy enrichment type (La N /Lu N <1; Seredin and Dai 2012), further indicating the influence of seawater and hydrothermal fluids (Seredin and Dai 2012;Dai et al. 2016a). Both seawater and hydrothermal fluids could lead to positive Y anomalies in coal and sedimentary rocks (Zhang et al. 1994;Bau et al. 1995;Dai et al. 2016a). ...
... For Nd, the data were also included from the eastern North Atlantic (GA02; Lambelet et al. 2016), the eastern tropical North Atlantic (GA11; Zieringer et al. 2019), the Pacific sectors of the Southern Ocean (GIPY06; Lambelet et al. 2018), and the polar South Pacific (GPc02; Basak et al. 2015). We also used pre-GEOTRACES observations plotted as black open circles in Fig. 1, which are compiled from data reported in pre-GEOTRACES literature (Elderfield and Greaves 1982;De Baar et al. 1983, 1985Sholkovitz and Schneider 1991;Piepgras and Jacobsen 1992;Bertram and Elderfield 1993;Sholkovitz et al. 1994;Zhang et al. 1994Zhang et al. , 2008Shimizu et al. 1994;German et al. 1995;Sholkovitz 1996;Nozaki 1996, 1998;Tachikawa et al. 1999b;Alibo and Nozaki 2000;Nozaki and Alibo 2003;Lacan and Jeandel 2004b;Hongo 2005). ...
In this study, we report our ocean general circulation model simulations of the global distribution of rare earth elements (REEs) in the ocean. As previously reported (Oka et al. in Glob Biogeochem Cycles 23:1–16, 2009), the vertical profiles of REEs in the North Pacific Ocean are strongly controlled by the reversible scavenging process, and the systematic differences between REEs can be reproduced in the model by selecting an appropriate model parameter which controls affinity to particles. We here demonstrate that the external REE input from the coastal regions also plays a role in controlling the vertical profiles of dissolved REE and their inter-basin differences. The role of the external inputs is especially important for light REEs, such as neodymium (Nd). The linear increase in Nd concentration in the North Pacific Ocean cannot be sufficiently reproduced by the reversible scavenging alone; rather, a combination of the reversible scavenging and the external inputs is necessary. On the other hand, the distribution of heavy REEs, such as lutetium (Lu), can be broadly reproduced without the external inputs, suggesting that Lu has similarity with conservative nutrient-like tracer. When compared with REE observations compiled from both the recently obtained GEOTRACES dataset and pre-GEOTRACES reported data, our simulations successfully reproduced the overall features of these observations. Observational data suggested that the vertical profiles of REEs are not the same among the basins; our model simulations demonstrate that this feature can be clearly reproduced by considering both the reversible scavenging and the external REE inputs from the coastal regions.
... Y/Ho ratios can also be used for evaluating the role of alteration. This ratio is 28 in fresh basaltic rocks (Bau 1996) and between 44 and 74 in altered rocks (Zhang et al. 1994;Bau et al. 1995). The Y/Ho ratios in the Kahak mafic-intermediate rocks range from 27 to 30, indicating that secondary processes were not significant. ...
Several gabbro, gabbroic diorite, and diorite intrusions were emplaced in the Neotethyan Urumieh-Dokhtar magmatic arc in the Kahak area of the Zagros Orogen. The plutonic rocks intruded Cenozoic volcanic and pyroclastic succession. U-Pb dating via LA-ICP-MS of zircon yields early to middle Eocene ages of ~53 to 38 Ma for the diorite and gabbroic diorite in Veshnaveh and Naragh areas and Miocene ages of 23 to 20 Ma for gabbroic rocks in the Kerogan and Fordou areas. The Eocene magmatic phase occurred quite possibly as three continuous pulses. The Eocene and Miocene intrusions have negative Nb-Ta anomalies like those of subduction-related magmas. The Pb isotopic compositions show the involvement of subducted sediment in the source of the studied samples. The Eocene intrusions are tholeiitic and enriched in incompatible-trace-elements (especially the HFSE) compared to the Miocene intrusions which are calc-alkaline and have lower concentrations of most incompatible trace elements. Sr-Nd isotopic compositions of the Eocene rocks lie close to the mantle array and near Bulk Silicate Earth, but the Miocene suite is shifted to higher (87Sr/86Sr)i. The higher (87Sr/86Sr)i, along with larger Ba, K, Pb, and Sr anomalies, in the Miocene suite imply more slab fluid input and/or crustal contamination. Apparently, the Eocene mafic magmas formed in slightly metasomatized sub-continental lithospheric mantle (SCLM), whereas the Miocene suite was derived from highly metasomatized, deeper levels of the SCLM. We suggest that slab roll back occurred between the Eocene and Miocene and transferred the location of mantle partial melting to greater depths.
... The relative abundance of Y can be calculated using the Y/Ho ratio (Bolhar et al., 2004;Shannon, 1976). Modern open marine seawater environments have Y/Ho ranging between 40 and 80 (superchondritic values), whereas nearshore waters have Y/Ho ranging from 33 to 40 (Zhang et al., 1994;Nozaki and Zhang, 1995;Bau et al., 1997). Further, the inclusion of terrigenous materials and volcanic ash in chemical sediments affects the Y/Ho ratio (chondritic value: ~28). ...
Upper Aptian-lower Albian seawater composition changes and redox conditions in limestones of the Agua Salada and Lampazos formations in Mexico were investigated by data of major oxides, trace elements, rare-earth elements, and stable isotopes. Most limestones of the Agua Salada Formation (Group 1) show REE + Y patterns consistent with precipitation from seawater whereas limestones from the upper part of the Agua Salada and Lampazos formations (Group 2) have non-seawater-like REE + Y patterns. The relationship among REE and major and trace elements indicates that contamination by detrital input is the main source of REEs, followed by Fe-oxyhydroxides. The variations in Ce anomalies were influenced by paleo-redox conditions. The carbon isotope values, low Mn/Sr ratio and absence of correlation between δ¹³C vs δ¹⁸O values suggest that δ¹³C retained its original marine signatures during diagenesis. The δ¹³C curve has several significant negative isotopic excursions in upper Aptian-lower Albian strata. The variations in δ¹³C values and their negative excursions, fossil evidence, positions of δ¹³C segments, and correlation of this curve with global reference curves permits documentation of OAE 1 b and the associated sub-events such as Jacob, Kilian, Paquier and Leenhardt sub-events.
... Rare-earth elements (REE) are a unique series of 14 lanthanide elements ranging from 57 La to 71 Lu (Nozaki 2001;de Baar et al. 2018). Due to its chemical similarity with REE, Yttrium ( 39 Y) has often been included as a pseudolanthanide element, and REE together with Y are known as REY (Zhang et al. 1994). Lanthanide elements have many similar physical and chemical properties, making them useful tracers for geochemical processes in marine environment, particularly in the case of the two REY that can have different oxidation states Byrne and Sholkovitz 1996;Nozaki 2001). ...
The concentrations of dissolved yttrium and rare earth elements (REY) in sediment pore water provide important geochemical information. However, due to the low REY concentration, complex matrix, and limited sample volume (often only a few milliliters), analysis of the REY in pore water often is highly challenging. In this study, a method was established to determine the dissolved REY in pore water of marine sediments using an offline preconcentration step with the ethylenediaminetriacetate chelating resin, followed by inductively coupled plasma-mass spectrometry. In addition, using a commercially available automated trace-element preconcentration system, the preconcentration step can be fully automated, saving labor and providing a better control of the final elution volume. The experimental conditions (pH, elution volume, elution acid concentration, and organic complexation effect) were assessed, and the optimal conditions were chosen. In particular, the organic complexation effect was found to be negligible. The procedure blank and limit of detection were satisfactory for studying REY in pore water of marine sediments, and the method also yielded satisfactory recoveries for the REY elements (83–110%). The method was then applied to analyze the dissolved REY concentrations of pore water samples collected in a sediment core (~ 30 cm) in the central Indian Ocean. The vertical distribution, dissolved REY concentration, and the average Post Archean Australian Shale-normalized pattern of the REY showed similarities to the previously published pore water REY data. This method provides an accurate yet facile approach for the analysis of all 15 REY in marine pore water samples using the sample volume of only ~ 5 mL.
... All of the studied Oligocene and Eocene facies except limestones have positive Y anomalies (Tab.2). The positive Y anomalies are compatible to the positive Y anomaly of sea water (Zhang et al. 1994;. In this respect the positive Y anomalies in the studied facies may be generated by REE sorption on the iron oxy-hydroxides rather than to be inherited from the Eocene and Oligocene sea water; because the Oligocene and Eocene marine limestones have no positive Y anomalies. ...
There is an apparent lack of regularity in the distribution of most lithofacies in the Late Eocene-Oligocene sediments at Wadi El Tayiba, Abu Zenima area, west central Sinai. This heterogeneous vertical distribution of most lithofacies records nine microfacies varieties with abrupt local variations in patterns of deposition. These lithofacies range from fossiliferous limestone of shallow marine origin to continental red beds which represent wide range of depositional environments. These were originated as river flood plains, alluvial fans, deserts and lakes, associated with dry and wet tropical climates. Although, both Tanka and Tayiba formations show different lithofacies, they have nearly similar REE distribution patterns. Furthermore, there is a direct correlation between the magnitude of Eu/Eu*, Ce/Ce* and Gd/Gd*; such a concomitant increase or decrease in different anomalies cannot be explained by changing depositional environment or redox state. They are interpreted by textural variation and post depositional diagenetic processes related to the rifting of the Gulf of Suez. All of the studied Eocene and Oligocene facies are characterized by LREE enrichment, negative Ce and Eu anomalies and positive Gd anomalies. The exceptions for these results are shales and limestones which have positive Eu and negative Gd anomalies, respectively. Both Oligocene basalt and sandstone facies have unusual Tm content. INTRODUCTION The study of REE in sedimentary rocks has been increasing over past decades. Rare earth elements are likely to be moved into clastic sedimentary rocks (shale in particular) without potential changes on their relative amounts and hence give information regarding source rock provenance. So, the relative REE patterns including the magnitude of the Eu anomaly, have been used to infer sources of sedimentary rocks (e.g. Piper 1974; Taylor and McLennan 1985; Wronkiewicz and Condie 1990). Basic rocks contain low LREE/HREE ratio and tend not to display Eu anomalies, whereas more silicic rocks usually contain higher LREE/HREE ratios and negative Eu anomaly. Cullers et al. (1979); Basu et al. (1982); Taylor and McLennan (1985) confirm that shales from different ages and localities, such as the post Archean shale of Australia (PAAS) and European shale (ES) have similar REE distribution patterns to that of NASC (North American Shale Composite). The main characteristics are the enrichment of LREE relative to HREE and the small negative Eu anomaly. Ronov et al. (1974) reported that the REE content of shale is inherited and relatively unchanged from their ultimate igneous and metamorphic rocks. The stratigraphic position and depositional history of the Eocene and Oligocene sequence of Wadi El Tayiba have been extensively debated. Among these studies are
... All of the studied Oligocene and Eocene facies except limestones have positive Y anomalies (Tab.2). The positive Y anomalies are compatible to the positive Y anomaly of sea water (Zhang et al. 1994;. In this respect the positive Y anomalies in the studied facies may be generated by REE sorption on the iron oxy-hydroxides rather than to be inherited from the Eocene and Oligocene sea water; because the Oligocene and Eocene marine limestones have no positive Y anomalies. ...
There is an apparent lack of regularity in the distribution of most lithofacies in the Late Eocene-Oligocene sediments at Wadi El Tayiba, Abu Zenima area, west central Sinai. This heterogeneous vertical distribution of most lithofacies records nine microfacies varieties with abrupt local variations in patterns of deposition. These lithofacies range from fossiliferous limestone of shallow marine origin to continental red beds which represent wide range of depositional environments. These were originated as river flood plains, alluvial fans, deserts and lakes, associated with dry and wet tropical climates. Although, both Tanka and Tayiba formations show different lithofacies, they have nearly similar REE distribution patterns. Furthermore, there is a direct correlation between the magnitude of Eu/Eu*, Ce/Ce* and Gd/Gd*; such a concomitant increase or decrease in different anomalies cannot be explained by changing depositional environment or redox state. They are interpreted by textural variation and post depositional diagenetic processes related to the rifting of the Gulf of Suez. All of the studied Eocene and Oligocene facies are characterized by LREE enrichment, negative Ce and Eu anomalies and positive Gd anomalies. The exceptions for these results are shales and limestones which have positive Eu and negative Gd anomalies, respectively. Both Oligocene basalt and sandstone facies have unusual Tm content. INTRODUCTION The study of REE in sedimentary rocks has been increasing over past decades. Rare earth elements are likely to be moved into clastic sedimentary rocks (shale in particular) without potential changes on their relative amounts and hence give information regarding source rock provenance. So, the relative REE patterns including the magnitude of the Eu anomaly, have been used to infer sources of sedimentary rocks (e.g. Piper 1974; Taylor and McLennan 1985; Wronkiewicz and Condie 1990). Basic rocks contain low LREE/HREE ratio and tend not to display Eu anomalies, whereas more silicic rocks usually contain higher LREE/HREE ratios and negative Eu anomaly. Cullers et al. (1979); Basu et al. (1982); Taylor and McLennan (1985) confirm that shales from different ages and localities, such as the post Archean shale of Australia (PAAS) and European shale (ES) have similar REE distribution patterns to that of NASC (North American Shale Composite). The main characteristics are the enrichment of LREE relative to HREE and the small negative Eu anomaly. Ronov et al. (1974) reported that the REE content of shale is inherited and relatively unchanged from their ultimate igneous and metamorphic rocks. The stratigraphic position and depositional history of the Eocene and Oligocene sequence of Wadi El Tayiba have been extensively debated. Among these studies are
... Y/Ho ratio would be discrepant from the chondritic value (Y/Ho = 28.8) for samples showing a tetrad effect (Zhang et al., 1994;Bau et al., 1996). The studied samples have Y/Ho ratios lower than the Chondritic value, one sample has chondritic ratio (sample 5), (Table 2). ...
Paleozoic rocks at Wadi El Sahu area are affected by many major faults in different directions. A reverse fault trending NE‐SW with exposure part length about 300m cutting throw the Abu Hamata and Adedia formations at the south side of Wadi El Sahu. A secondary ascending hydrothermal solution carrying heavy metals and radioactive minerals passing throw the fault plain and the surrounding fractures forming mineralized and radioactive zone. The mineralized zone thickness is ranging between 60cm to 200 cm along the fault plain. These rocks were analyzed radiometrically by portable gamma‐ray spectrometer, chemically by ICP‐ES and ICP‐MS, mineralogically by binocular and Environmental Scanning Electron microscope. Also, gold contents were determined by fire assay technique. REE and U contents reach up to 2682 and 1216 ppm, respectively. Mineralogical investigations indicate the presence of uraninite, torbernite, autunite, sklodowskite, kasolite as uranium minerals, thorite as thorium mineral, monazite, allanite and xenotime as REE‐bearing minerals, zircon and columbite as accessory minerals, gold and nickel as precious and base metals, in addition to cassiterite, chalcopyrite, chalcocite and chrysocolla. High REE and U contents are attributed to the circulation of epigenetic U and REE‐bearing hydrothermal solutions along the fault plain and its surrounding fractures. Hydrothermal alteration processes could be confirmed by the presence of M‐type tetrad effect in the REE‐patterns of ferruginous sandstone. The non‐ Chondritic ratio of Nb/Ta, Zr/Hf and Y/Ho in the studied sandstone may be attributed to the tetrad effect. Ce and Eu anomaly with unusual REE‐patterns represented by the presence of conjugated M‐W tetrad effects indicate dual effect of hydrothermal solutions or underground and seawater. The results clarify that the tetrad‐effects could be used as an evidence for environment of deposition and as indication for gold mineralization.
... In addition, felsic-intermediate rocks generally have weak or no Y anomalies, so coals with input of felsic-intermediate terrigenous materials would be expected to exhibit weak or no Y anomalies [38]. By contrast, seawater usually has positive Y and Gd anomalies [38,41,61,71,72]; hence, coals with positive Y and Gd anomalies may have been formed in a marine sedimentary environment. In the present research, the roof, partings, and coals adjacent to the roof and partings show weak Y anomalies (Appendix A Table A5), which was thought to have been inherited from the felsic-intermediate sediment provenance. ...
Mineralogical and geochemical characteristics of coals provide crucial information on their potential clean, efficient, and integrated utilization. In this paper, the mineralogical and geochemical behaviors of the No. 5 coals of the Taiyuan Formation in the Weibei Coalfield, North China, were investigated, and their geological controlling factors were subsequently discussed. The minerals in the Weibei coals mainly consist of kaolinite (8.3%), calcite (5.0%), and pyrite (3.1%), with minor proportions of tobelite (2.9%), dolomite (1.7%), quartz (1.8%), and traces of siderite (0.4%) and gypsum (0.6%). Several critical elements, including Nb (19.8 mg/kg), Ta (3.6 mg/kg), Zr (71.0 mg/kg) and Li (32.3 mg/kg), occur at concentrations higher than those averages for world hard coals, making the Weibei coals potential sources of these critical elements. Several factors, terrigenous material, seawater invasion, and hydrothermal fluids are responsible for these mineralogical and geochemical characteristics. The L-type rare earth elements and yttrium (REE-Y) enrichment in the roofs and partings, Al2O3-TiO2 and Zr/TiO2-Nb/Y plots, and negative Eu and weak negative Ce anomalies in the Weibei coals indicate a felsic-intermediate dominated sediment provenance primarily derived from the Qilian-Qinling Oldland on the South. Marine bioclastic limestone, negative Ce and positive Y anomalies in coals imply the influence of seawater on the Weibei coals. Last but not least, the cleat-infilling and/or fracture-infilling calcite, pyrite, barite, and tobelite as well as the positive Eu and Gd anomalies, H-type, and M-type REE-Y enrichment patterns suggest the influence of hydrothermal fluids, which lead to re-distribution of some critical elements from roof and parting to the underlying coal seam.
... The remaining areas without positive Eu anomalies (~1.0) may be weakly or not influenced by hydrothermal fluids. Y/Ho ratio Using previously established methods for the determination of Y and other REEs, Zhang et al. (1994) and Bau et al. (1996) showed that the oceanic distributions of Y closely resemble those of Ho because they have similar physical and chemical properties, such as being trivalent and having a similar ionic radius and electronegativity. However, the geochemical behavior of Y and Ho differs in various environments. ...
Abstract: To explore the shallow marine redox state from the Ediacaran to the Cambrian (ca. 635-488.3 Ma) Yangtze Platform in southern China, this study presents traditional rare-earth element (e.g. δCe, δEu, REE distribution pattern and Y/Ho), enrichment factor, and paleoenvironment proxy data from the Kaiyang shelf from Nantuo to Loushanguan Formations. Our data from a drill core from Kaiyang suggest the occurrence of a fluctuating redox state from the Ediacaran to the Cambrian ocean, in which the fluctuating redox state of shallow water coexisted with eustatic change. We observe an obvious oxygenation signal of seawater during Ediacaran-Cambrian transition and a distinctive redox state in Ediacaran and Cambrian shallow seawater. We posit that the large-scale oxygenation of the atmospheric-oceanic system may have played a critical role in the main phase of Cambrian Explosion, and a fluctuating redox state of shallow seawater existed at the Cambrian stage.
Key words: Redox state; Ediacaran-Cambrian transition; Trace elements; REE; Eustatic change
The Algerian-Tunisian phosphorites, from Paleocene-Eocene, were mainly deposited around “Kasserine Island” into three main basins as a result of the large Tethyan phosphogenesis. This chapter reviews the main characteristics of the most representative phosphorite deposits with the aim of comparing their lithostratigraphy, petrography, mineralogy, and geochemical features (major and trace elements, and isotopes), in order to summarize the current state of knowledge of their depositional environments. The phosphorites while sharing similar characteristics in terms of lithology and petrography, also show significant variations in thickness and vertical configuration mostly related to the depth of local basins and depositional facies. Phosphorites are often made up of a complex carbonate fluorapatite (CFA) mineral phase that arises from a microbial-driven phosphatization process of former particles (pellets, coprolites, and bioclasts). The mineral exo-gangue is mainly represented by dolomite, calcite, quartz, gypsum, heulandite-clinoptilolite, and Opal-CT in addition to some accessory minerals. P2O5 contents range from 17.97 wt% to 35.00 wt% (median = 26.5 ± 3.59 wt%), and consequently the values of other oxides fluctuate in different phosphorites facies. Contents of trace elements and rare earth elements (REE) vary significantly through the deposits (e.g. ~0.8 ppm < Cd > ~172 ppm; ~101 ppm < Cr > ~374 ppm; ~2 ppm < Cu > ~44 ppm; ~16 ppm < U > ~126 ppm; ~125 ppm < ∑REE > ~1018 ppm). REE + Y-geochemistry shows that the northern deposits formed under oxic conditions, while the eastern and southern deposits formed in sub-reduced to sub-oxic environments. There, a little detrital input and slight paleoproductivity occurred, as revealed by detrital and paleoproductivity geochemical proxies. This realm, associated with the δ13C, δ18O, and 87Sr/86Sr isotopic records, contrasts with the occurrence of the Paleocene Eocene Thermal Maximum (PETM) global warming event during the phosphorite formation.
The "septarian barite concretions" have garnered significant interest worldwide. This study presents the first detailed investigation of these sedimentary structures in Algeria, with a primary focus on elucidating their genesis through petrography, SEM-EDS, major and trace elements (including REEs), and sulfur isotope analysis. The sampled concretions are prevalent in Upper Cretaceous-Paleocene marl layers from the Biban area, primarily in two main sectors (Koudiat Djebassa and Sidi Ziane), situated within the Southern Tellian Atlas of the Alpine chain in Northern Algeria (Maghrebides). While these barite concretions exhibit diverse morphologies, our analysis focuses specifically on oblate ellipsoidal concretions. The flattened shape of these concretions may stem from compressed echinoid tests or small, oblate septarian cracked concretions representing the flattened cores. Notably, these concretions feature an outer cortex of radial fibrous barite crystals, measuring centimeters in thickness. Petrographic examination coupled with SEM-EDS analysis suggests that concretion growth occurred from porewaters in unconsolidated, soft sediments at shallow burial depths beneath the sediment-water interface, manifesting in three growth episodes: (i) an initial stage characterized by primarily thin lamellar barite crystals intertwining to form rosette-like structures in concretion cores, (ii) a later stage marked by radial-fibrous barite crystal growth in concretion margins, and (iii) the filling of cracks by septarian barite. The presence of terrigenous sediment, particularly abundant in rosette-like barite crystals, indicates growth within highly porous sediment. Conversely, the radial fibrous outer cortex is related to an effective displacive growth mode. The δ34S values of the barite concretions (ranging from 16 ‰ to 24.4 ‰), consistent with seawater values, which support that seawater was the primary sulfur source. Furthermore, REE geochemistry further supports the seawater origin of diagenetic fluids rather than a hydrothermal one. Concretions are suggested to have formed in organic-rich, fine-grained sediments at shallow depth below the sea floor, in sedimentation halts, and as a result of microbial degradation of organic matter. Barium was supplied to porewaters within the methanogenic zone, precipitating as barite upon migration upwards to the boundary with the overlying sulfidic zone.
Based on new field, petrographic, and whole-rock geochemistry data, we investigated three discrete metagabbro-diorite complexes (MGDC) across the E-W Sinai to contribute to increasing knowledge of the evolution of the juvenile continental crust of the Neoproterozoic Arabian–Nubian Shield. The three MGDCs vary in the dominance of the gabbroic versus dioritic rock types among each of them. Gabbroids are distinguished into pyroxene-hornblende gabbros and hornblende gabbros, whereas dioritic rocks have been subdivided into diorites and quartz diorites. The studied MGDC rocks are almost metaluminous and possess prevalent calc-alkaline characteristics over subsidiary tholeiitic and alkaline affinities. The most distinctive feature in the profiles of the investigated MGDCs on the N-MORB-normalized spider diagrams is the coincidence of stout negative Nb anomalies and projecting positive Pb spikes, which is typical of igneous rocks evolved in subduction zones. The three MGDC samples exhibit variably LREE-enriched patterns [(La/Yb)N = 4.92–18.55; av. = 9.04], either lacking or possessing weak to negligible positive and negative Eu anomalies. The calculated apatite and zircon crystallization temperatures reveal the earlier separation of apatite at higher temperatures, with the obvious possibility of two genetic types of apatite and zircon in the magma (cognate vs. xenocrystic) since both accessories have yielded very wide ranges of crystallization temperatures. The investigated MGDCs were formed in a continental arc setting, particularly a thick-crust arc (>39 km). The parent magmas comprised components derived from the melting of the mantle wedge, subducting oceanic lithosphere, and subducting overlying sediments. The mantle input was from a spinel–garnet transitional mantle source at a depth of ca. 75–90 km. The impact of slab-derived fluids was much greater than that of slab-derived melts, and so subduction-related fluids had a crucial effect on metasomatizing the partially melted mantle source. The parent mantle-derived magma has been subjected to substantial crustal contamination as a dominant mechanism of differentiation.
Phosphate rocks, an important ore resource in Guizhou Province, China, are mainly hosted within the Sinian Doushantuo Formation and the Cambrian Meishucun Formation. In addition, the phosphate rocks of the Cambrian Meishucun Formation are rich in biological fossils. Although numerous studies investigating the genesis of phosphate deposits have been performed, the relationship between biological activity and the formation of phosphate deposits in the lower Cambrian Meishucun Formation has not been convincingly explained. This study focuses on the biological fossil assemblage, the characteristics of phosphorus, and the relationship between biological and phosphorus enrichment of the lower Cambrian phosphorites. The primary objectives of our study are to analyze the role of organisms in the formation of phosphorites, restore the phosphorus-formation environment of the Cambrian Meishucun Formation, and construct a sedimentary model of the phosphorites in the Meishucun Formation. The results indicate that there is a significant positive correlation between biological activity and the deposition of phosphorites, that is, the higher the degree of biological enrichment and differentiation, the stronger the deposition. The geochemical analysis of several profiles in the Zhijin phosphorite block shows that the phosphorite block was deposited in an oxygen-rich environment and was affected by a high-temperature hydrothermal fluid. Upwelling ocean currents supplied abundant phosphorus and other nutrients, which provided the conditions for small shells and algae to flourish. Biochemical activity was a crucial factor in the deposition of the phosphorite.
“Old phosphorite” deposits (Ediacaran to early Cambrian) located in Central Guizhou, South China, are hosted in carbonate and represent the earliest phosphogenesis. These old phosphorites, as well as Pliocene to Pleistocene and modern phosphate sediments (recent phosphorite) have been extensively studied. However, the possibility of recent phosphorite being the incipient stage of long-time phosphorite remains uncertain. Taking Weng’an (Ediacaran) and Zhijin (early Cambrian) phosphorites as examples, this study conducted in situ geochemical and mineralogical analyses of phosphate minerals (old apatites). Analogies between recent and old apatites were determined by comparing geochemistry based on rare earth elements (REE) and yttrium (REE+Y). Old phosphorite could be divided into authigenic grains and biodetritus, both comprising closely accumulated apatite nanocrystals. REE+Y concentrations (∑REE+Y) were much higher in the outer rim than in the inner core of biodetritus, whereas the authigenic grains showed relatively homogeneous REE+Y distributions. Three REE+Y patterns were observed: (1) “left-inclined” type, with no Ce anomalies; (2) shale-like pattern, with weak MREE enrichment and slightly negative Ce anomalies; (3) “hat-shaped” pattern, with notable MREE enrichment, evident HREE depletion, and remarkable negative Ce anomalies. Positive La, Gd, and Y anomalies, as well as MREE enrichment increased from type (1) to type (3), which can be explained by increasing degrees of oxidation. The REE+Y distributions of old apatites were similar to those of recent apatites, but exhibited MREE enrichment and HREE depletion and old authigenic apatites had no Ce anomalies. Furthermore, old apatite compositions lie in the diagenetic area on Y/Ho vs SmN/YdN plots. These characteristics indicate that old phosphorite could have been subjected to long-term diagenetic modification after burial, during which apatites recrystallized and absorbed REE+Y. Hence, it can be concluded that recent apatites could serve as predecessors of major ancient phosphorite, especially biogenic phosphorites. Globally, typical old phosphorites have quite variable REE+Y compositions, suggesting that the phosphorites experienced different depositional conditions and diagenetic alteration despite their contemporaneous formation. This study provides new data and insight on the diagenesis of old phosphorite and improves our deeper understanding of phosphogenesis in paleo- and modern environments.
Large phosphorite deposits in Central Guizhou, China, were formed around the Precambrian/Cambrian boundary (PC/C), including the Ediacaran (Doushantuo stage) and early Cambrian (Gezhongwu stage). Among them, Gezhongwu phosphorite from Zhijin are enriched in rare earth elements (REE) plus yttrium (REY), reaching 3.503 million tons. Although phosphorites have attracted great attention, the P and REY sources remained unclear. To determine the sources of P and REY and establish a phosphogenic model of PC/C phosphorite deposits, we present an integrated dataset of Mo and phosphate O isotopes for the first time, along with carbonate C isotope, geology, petrology, and geochemistry analysis. In all samples, δ¹⁸Op, Y/Ho, and Zr/Hf decreased from the Ediacaran to the early Cambrian, indicating increased terrigenous weathering fluxes while decreased upwelling water input. Furthermore, terrigenous weathering delivery significantly elevated marine REY concentrations in the Cambrian in Zhijin. The Ceanom and δ98/95Mo suggest that seawater was oxidized in the later Ediacaran and became entirely oxic in the early Cambrian. The positive feedback between oxygen levels in atmosphere and primary productivity caused progressive oxygenation in ocean-atmosphere system and enable phosphorites to be formed by different mechanisms. Results show that the Lower Doushantuo consisted of abiotic intraclasts and exhibited “seawater-like” REY types, indicating abiological and mechanical reworking phosphogenesis. Conversely, the Upper Doushantuo and Gezhongwu contained microbial debris and abiogenic intraclasts, and exhibited “hat-shaped” REY plots, suggesting microbially mediated phosphogenesis. Based on this data set, we developed a phosphogenic model illustrating formation of these two phosphorite deposits, wherein the Lower Doushantuo phosphorite formed through the reworking of pre-existing phosphatic sediments in anoxic and abiotic ocean, whereas the Upper Doushantuo and Gezhongwu phosphorite formed via microbial metabolisms in oxic and biotic conditions. The study provides an implication of PC/C phosphorite generative processes, as well as to improve our understanding of paleoenvironmental conditions.
Conodont elements are calcium phosphate (apatite structure) mineralized remains of the cephalic feeding apparatus of an extinct marine organism. Due to the high affinity of apatite for rare earth elements (REE) and other high field strength elements (HFSE), conodont elements were frequently assumed to be a reliable archive of sea-water composition and changes that had occurred during diagenesis. Likewise, the crystallinity index of bioapatite, i.e., the rate of crystallinity of biologically mediated apatite, should be generally linearly dependent on diagenetic alteration as the greater (and longer) the pressure and temperature to which a crystal is exposed, the greater the resulting crystallinity. In this study, we detected the uptake of HFSE in conodont elements recovered from a single stratigraphic horizon in the Upper Ordovician of Normandy (France). Assuming therefore that all the specimens have undergone an identical diagenetic history, we have assessed whether conodont taxonomy (and morphology) impacts HFSE uptake and crystallinity index. We found that all conodont elements are characterized by a clear diagenetic signature, with minor but significant differences among taxa. These distinctions are evidenced also by the crystallinity index values which show positive correlations with some elements and, accordingly, with diagenesis; however, correlations with the crystallinity index strongly depend on the method adopted for its calculation.
The distribution of the anthropogenic radionuclide ²⁴¹Am, a decay product of ²⁴¹Pu discharged from atmospheric tests of nuclear weapons, was investigated to resolve its horizontal and vertical migration in the Tropical East Pacific. We analyzed ²⁴¹Am concentrations in seawater samples collected in 2003. On comparing the ²⁴¹Am concentrations with the previously determined concentrations of ²³⁹⁺²⁴⁰Pu in the same samples, the vertical profiles of ²⁴¹Am were found to be similar to those of ²³⁹⁺²⁴⁰Pu. At some stations, the maximum concentration of ²⁴¹Am occurred 100–200 m deeper than that of ²³⁹⁺²⁴⁰Pu. The ²⁴¹Am/²³⁹⁺²⁴⁰Pu ratios in the North Pacific and South Pacific were comparable to one another, and were the typical ratio for the Pacific. The ²⁴¹Am distribution was influenced by the water mass at depths below 400 m. The ²⁴¹Am data support the view there is a current flowing at depths of 400–3000 m from the North Pacific through the Equator to the South Pacific. In addition, the ²⁴¹Am vertical profile was explained by using a 1-D scavenging model that considers the decay of ²⁴¹Pu and adsorption and scavenging by suspended particles. The different depths for the maximum concentrations of ²⁴¹Am and ²³⁹⁺²⁴⁰Pu observed at some stations were well explained by the model and by the distribution of CaCO3 particles. The residence time of ²⁴¹Am in the Pacific was also estimated by using the model.
Vessels made of chalk are common at Jewish sites throughout the southern Levant during the Roman period, apparently because stone was perceived to be impervious to ritual impurity. The present study analyzes samples from settlement and production sites to determine whether distinctive geochemical compositions might relate to specific source locations, and thus to provide the basis for conducting future large‐scale provenance studies. Distinctions between major elements, trace and rare‐earth elements as well as δ¹⁸O and δ¹³C isotopic compositions make it possible to discriminate between chalk sourced from Galilee and chalk from Judea.
Thirteen nodules and 12 sediments from the S.W. Pacific, including six nodule/sediment pairs, have been analysed by spark source mass spectrometry for 12 rare earth and 13 minor elements. The nodules appear to be relatively uniform in composition, e. g. La varies by a factor of 2.3. This finding adds weight to the contention that the S.W. Pacific constitutes a discrete nodule province distinct from that of the equatorial N. Pacific. The S.W. Pacific sediments show a much wider range of composition, e. g. La varies by a factor of 7.7. The decreasing sedimentation rate (and therefore increased oxidation state) with increasing distance from New Zealand is primarily responsible for this variation. As, Nb, REE (rare earth elements), Y, Sr, Th, Zr, Sn, Pb, U and Hf increase in concentration in the sediments with increasing distance from New Zealand, whereas Rb, Ba and Cs decrease. The former group of elements are therefore incorporated mainly in the authigenie component of the sediment, whereas the latter group are associated mainly in the silicate component. The equatorial N. Pacific nodule is lower in REE and a number of other minor elements, and higher in Rb and Cs, compared with the S.W. Pacific nodules. This finding is surprising in view of the much higher Cu and Ni contents of these nodules and may reflect the higher detrital silicate contents of the equatorial N. Pacific nodule. The REE content of the Hawaiian-Emperor Seamount Chain nodules and crusts are somewhat higher than those of the S.W. Pacific nodules. Lower concentrations of Pb in the Hawaiian-Emperor deposits suggests that this element is not always oxidized to the tetravalent state in such elevated deposits. The iron-rich Eniwetok Atoll sample is extremely in REE which indicates that this deposit has formed extremely rapidly as presviously noted in some other near-shore deposits.
We have found that lanthanide tetrad effect (PEPPARD et al., 1969) is operative for heavy rare-earth elements (REE) in a phosphorite sample (GOLDBERG et al., 1963). Also it has been evinced that the similar effect is observed for REE in sea waters. However, in the case where the plot (Masuda-Coryell plot) is void of the points for Tb, Ho and Tm, the resultant joint-line pattern is to have the common characteristics that the zigzag pattern is pointed downward at Dy and Yb and upward at Er. That is, the zigzag pattern with phase coincidence in breaking and its direction is a partially cut-off reflection of lanthanide tetrad effect. Employing the stable isotope dilution technique, we could determine REE in one-liter sample of sea water, with errors less than 2 ~3%.
Analyses for the rare-earth elements in sea water, in a phosphorite, and
in a manganese nodule were made by neutron activation and x-ray fluorescence
techniques. These marine samples showed a depletion in the heavier rareearth
elements, relative to chondritic meteorites, beginning with samarium. Cerium was
enriched in the manganese nodule, probably as a result of its oxidation to the 4+
valence state. The ratios of the rare-earth abundances in the two minerals to
those of sea water go through a maximum in the vicinity of samarium. The
europium concentration, often anomalous in terrestrial minerals, was normal
relative to the other rare earths in all of the samples. The sea water showed
four times the concentration of rare earths at a depth of 4000 meters as compared
with surface values. (auth)
During the GEOSECS-II test cruise a profile of 25 large volume water samples were collected, filtered and stored in the acidified condition. Two laboratories have together determined Fe, Cu, Zn, Co, Sb, Cs and U in these samples. Both laboratories determined Zn and the correlation is good; Zn, Fe and Cu show a maximum in the North Atlantic Deep Water, Cs and U are essentially conservative and Sb show variability within the uncertainty of the technique. Sc is more abundant in deep water than surface water in both the Atlantic and Pacific Oceans.
Comparisons of yttrium and rare earth stability constants for organic ligands indicate that Y(III)-organic complexation behavior most closely resembles, on average, the complexation characteristics of Sm(III). Yttrium organic complexation behavior distinctly differs from the behavior of Ho(III), whose ionic radius is most similar to that of yttrium. However, our stability constant comparisons demonstrate that the most reliable basis for predicting Y(III) organic stability constants are predictions based on the complexation behavior of Ho(III). Linear free energy relationships between Ho(III) and Y(III) exhibit better fits than those obtained for other rare earth elements, and much better fits than those obtained between Sm(III) and Y(III). The comparative abundances and distributions of yttrium and the rare earths in seawater are controlled by competitive equilibria between inorganic solution ligands and organic surface ligands. Due to yttrium solution complexation with hard inorganic ligands resembling that of Ho(III) and, yttrium surface complexation with soft organic ligands resembling that of light rare earth elements, the input normalized abundances of yttrium and the rare earths should be decoupled in seawater. In its seawater scavenging behavior, yttrium should act as a pseudolanthanide even heavier than the heaviest rare earth element, lutetium.
This paper presents a table of abundances of the elements in the various major units of the Earth's lithic crust with a documentation of the sources and a discussion of the choice of units and data.
Carbonate stability constants for five rare earth elements (Ce[sup 3+], Eu[sup 3+], Gd[sup 3+], Tb[sup 3+], and Yb[sup 3+]) have been determined at t = 25[degrees]C and 0.70 [plus minus] 0.02 M ionic strength through solvent exchange techniques. Estimated stability constants for Ce, Eu, and Yb are in close agreement with previous work. Analyses using Gd and Tb provide the first carbonate stability constants for these elements based on direct measurements. The authors' measured stability constants were used to estimate carbonate stability constants for the entire suite of REEs. Their Eu, Gd, and Tb carbonate stability constants demonstrate the existence of a Gd-break': Carbonate stability constants for Gd are smaller than those for Eu and Tb. In analogy to Gd concentration anomalies reported in field observations, Gd stability constant anomalies have been defined in terms of the difference log [sub L][beta][sub n](Gd) [minus] log [l brace]([sub L][beta][sub n](Eu) + [sub L][beta][sub n](Tb))/2[r brace], where [sub L][beta][sub n](M) = [ML[sub n]][M[sup 3+]][sup [minus]1][L][sup [minus]n]. Examinations of REE-organic stability constants demonstrate that 106 out of 125 organic ligands have negative Gd anomalies in their first stability constants. The magnitudes of negative Gd anomalies generally become greater with increasing magnitude in Gd-ligand stability constants. Field observations of positive anomalies in shale-normalized Gd concentrations can be explained in terms of REE scavenging by organic surface ligands, such as polyaminocarboxylic acids, which possess a more negative Gd anomaly than carbonate ligands. The authors' modeling efforts indicate that a mixture of strongly complexing organics such as mono- and dicarboxylic acids is consistent with the pattern of REE scavenging by marine particulate matter. 28 refs., 6 figs., 3 tabs.
The rare-earth elements in a composite of European shales originally analyzed by Minami in 1935 have been analyzed by neutron
activation. The apparent europium deficiency and the differences in relative elemental abundances for the rare earths from
American and Russian sediments, as in ferred from the older values, are obviated.
From the vertical distributions of the rare-earth elements (REE) in the Sargasso Sea we now report the first profiles of Pr, Tb, Ho, Tm and Lu in seawater, together with profiles for La, Ce, Sm, Eu and Yb. The first observations of positive Ce anomalies in seawater are ascribed to reducing inshore sediments as a source for Ce (ref. 1). All vertical profiles are consistent with adsorption of trivalent rare earths by settling particles, possibly siliceous or calcareous, followed by their release at or near the sea floor on dissolution of the carriers. The very different Ce profile demonstrates the additional effects of oxidation–reduction reactions.
A method for the analysis of sub parts per trillion levels of rare-earth elements (REEs) and yttrium (Y) in seawater after preconcentration with solvent extraction and back-extraction has been developed. Almost perfect extraction and back-extraction of all REE and Y were achieved by single extraction, and most of the matrix elements were removed during the extraction procedure. Even after 200-fold preconcentration, matrix problems by ICP-MS measurement were negligible. Contamination from reagents and water used during the pretreatment was below 1% of the concentration of REE and Y in seawater. The standard deviation obtained for triplicate separation of 100- and 1,000-mL samples of the same seawater was better than 5% for all REE. The average precision of the measurement for all REE and Y after preconcentration of 1,000 mL of raw seawater to 5 mL of final measurement solution was calculated to be less than 2.5%. Since there is no standard seawater sample for REE and Y, in order to evaluate this novel technique, the analytical results obtained by this method were compared with those obtained by isotope dilution mass spectrometry coupled with Fe coprecipitation.
We present new, highly precise and accurate data for ten rare earth elements (REEs) in two water column profiles and in bottom waters from three additional localities in the North Pacific. Our results presented here, and in an earlier publication, indicate that the water column in the western North Pacific is stratified with respect to the isotopic composition of Nd as well as Nd/La, Sm/Nd, and Er/La. Both the Nd isotopic and the REE data show that REE transport is strongly influenced by horizontal advection, even in the sluggish circulation of the Pacific. In general, REEs increase in concentration with depth. At mid-latitude, they reach a maximum concentration, at about 3000 m, and then decrease to the bottom. At high latitude, heavy REEs reach a maximum concentration near 3000 m, whereas light REEs continue to increase in concentration with depth. The deep water maximum and bottom water depletion is interpreted as an advective feature resulting from the flow of a lower concentration of REEs in Antarctic bottom water under a higher concentration of REEs in the North Pacific. Concentrations of REEs do not show a linear relationship with those of Si, indicating that the REE cycle is not directly coupled to that of the Si cycle. REE element ratios (i.e., Nd/La) correlate with hydrographie properties, which suggests that major features of the REE patterns may be conserved during lateral transport. Comparison of our REE data to those in previously published reports on Pacific seawater shows that the identification of REE distributions affected by advection is only made possible by the high-precision analysis we developed for this study. The Ce-concentration we observe is relatively constant over 200–4500 m depth at both sites where we have complete profiles. This unique constancy of Ce is in contrast to the contiguous REEs, La, and Nd, which show substantial concentration variations with depth.
A suite of Australian shales, greywackes and subgreywackes ranging in age from Proterozoic to Triassic were analyzed for the rare earth elements (REE) in order to detect any secular changes in rare earth distribution. These post-Archean sediments show remarkably similar relative rare earth patterns. They are characterized by negative Eu anomalies of almost constant magnitude () relative to chondrites and nearly constant ratios of light to heavy rare earths (average ∑LREE/∑HREE = 9.7 ± 1.8).The REE abundances are generally higher in the younger sediments which may suggest that the absolute abundances of the rare earths in clastic sediments have gradually increased with time. Since no secular change in relative rare earth distribution was detected in the post-Archean sediments, a uniform process of crustal growth and evolution seems to have operated over the past 1500 million years at least.Australites show rare earth distributions very similar to that of the average clastic sediment. This suggests that the tektite parent material originated in the upper crust.
Vertical profiles of Cd, Zn, Ni, and Cu have been determined at three stations in the North Pacific and in the surface waters on a transect from Hawaii to Monterey, California. The distributions found are oceanographically consistent and provide a needed confirmation and extension of several recent studies on the marine geochemistries of these metals. Cadmium concentrations average 1.4 pmol/kg in surface waters of the central North Pacific and show a strong correlation with the labile nutrients, phosphate and nitrate, increasing to values of 1.1 nmol/kg at depths corresponding to the phosphate maximum. Zinc is depleted in surface waters of the central gyre to an average value of 0.07 nmol/kg and increases to a deep maximum of 9 nmol/kg exhibiting a strong correlation with the nutrient silicate. Nickel concentrations average 2.1 nmol/kg in surface central gyre waters and increase to a deep maximum of 11 nmol/kg. Nickel is best correlated with a combination of phosphate and silicate. Copper averages less than 0.5 nmol/kg in surface waters of the central North Pacific and increases gradually to values of 5 nmol/kg in bottom waters. The Cu profiles show evidence of intermediate and deep water scavenging. The involvement of these metals in the internal biogeochemical cycles of the sea is responsible for their distributions which are predictable on the basis of oceanographic parameters.
Two profiles of the rare earth elements (REEs) are reported for the upper water column of the Sargasso Sea. The trivalent-only REEs have remarkably constant concentrations in the upper 500 m of an April 1989 profile and in the upper 200 m of a May 1989 profile. In contrast, Ce concentrations decrease smoothly with increasing depth. In April 1989 Ce decreases from 15.7 pmol/kg at 20 m to 5.1 pmol/kg at 750 m. Cerium, which has Redox transformations in seawater, behaves anomalously with respect to its REE(III) neighbors. While both dissolved Ce and Mn have elevated concentrations in the upper 200 m, their vertical gradients are distinctly different. In contrast to Mn, which reaches a minimum dissolved concentration near the zone (150–250 m) of a particulate Mn maximum, Ce is being removed both near this zone and to depths of at least 750 m.
Sargasso Sea suspended particles were sequentially digested with three chemical treatments (acetic acid, mild HCl/HNO3 and HF/HNO3/HCl in a bomb). The latter two treatments dissolve detrital minerals, while the acetic acid removes surface coatings (organic matter and Mn oxides). The rare earth element (REE) composition of the surface coatings, in marked contrast to the crust-like REE composition of the two detrital phases, is extensively fractionated with respect to both filtered seawater and the crust. Surface coatings are responsible for the removal and fractionation of REEs from seawater and, as such, play a key role in the marine geochemical cycles of trace elements.Relative to seawater, the surface coatings are systematically enriched tenfold across the trivalent REEs from Lu to La and develop large positive Ce-anomalies. The Ce-anomalies of the coatings switch from being negative (seawater-like) in the upper 100 m to being strongly positive at greater depths. The ingrowth of Ce and LREEs on particle surfaces reflects the in situ oxidation of dissolved Ce(III) to particulate Ce(IV) and the preferential removal of LREE(III)s over HREE(III)s. REEs(III) fractionation of this type is consistent with particle/solution models. Both processes appear to be related to the in situ formation of Mn oxide particles from the oxidation of dissolved Mn(II) in the upper 200 m of the water column. Preferential removal of LREEs in the upper waters is countered by their preferential release at depth due to remineralization of surface coatings on particles.A new method is explored for estimating the residence time of suspended particles by combining Ce concentration data of dissolved and surface-bound phases with the Ce (III) oxidation rate measurements of Moffett (1990). A Ce-based residence time of thirteen days is similar in magnitude to the value calculated from U-234Th disequilibria in the Sargasso Sea.
Profiles of REE concentrations and neodymium isotope measurements in the western Indian Ocean are consistent with published data from the other major oceans. REE concentrations show a strong hydrographic control. The influence of intermediate water masses is particularly significant. Surface water concentrations vary with salinity. Paniculate REEs are less than 5% of dissolved concentration, except for Ce, where up to ~20% of total REEs are present as >0.4 μm particles. In contrast to dissolved profiles, concentration profiles of paniculate REEs, including Ce, all increase with depth. REE concentrations correlate with silica over all but the deepest waters, although, in detail, correlations are complex. The neodymium isotopic composition of Indian Ocean seawater (avg. ϵNd(0) = −8.3) is intermediate between that for the Atlantic and Pacific oceans. Comparison of REE data from the major oceans shows that the HREEs behave more like Si than do the LREEs. Sm/Nd ratios are near-constant for all oceans, whereas ratios vary between the Atlantic, Indian, and Pacific oceans. The fractionation of the REEs in surface seawaters can be explained by fractionation factors relative to silica from ~0.12 for La to 0.05 for Er. Use of a seven-box model shows that the interoceanic variations in neodymium isotopic compositions and Nd concentrations cannot be reconciled unless particle-water exchange is invoked. The degree of exchange required is consistent with particle residence times of ~1–10 yr.
The first profiles of Pr, Tb, Ho, Tm and Lu in the Pacific Ocean, as well as profiles of La, Ce, Nd, Sm, Eu, Gd and Yb, are reported. Concentrations of REE (except Ce) in the deep water are two to three times higher than those observed in the deep Atlantic Ocean. Surface water concentrations are typically lower than in the Atlantic Ocean, especially for the heavier elements Ho. Tm, Yb and Lu. Cerium is strongly depleted in the Pacific water column, but less so in the oxygen minimum zone. The distribution of the REE group is consistent with two simultaneous processes: 1.(1) cycling similar to that of opal and calcium carbonate2.(2) adsorptive scavenging by settling particles and possibly by uptake at ocean boundaries. However, the first process can probably not be sustained by the low REE contents of shells, unless additional adsorption on surfaces is invoked. The second process, adsorptive scavenging, largely controls the oceanic distribution and typical seawater pattern of the rare earths.
Rare earth element (REE) patterns in the deep Pacific are strongly depleted in the lighter elements and have a large negative cerium anomaly. These REE patterns and associated concentration-depth profiles are maintained by regeneration in deep waters modified by preferential scavenging of the lighter elements. Scavenging by iron- and manganese-rich hydrothermal plumes might explain why vast areas of sediments far removed from spreading centres contain a metalliferous component.
The depth distributions of La, Ce, Nd, Sm, Eu, Gd, Dy, Er and Yb in the oceanic water column are used to evaluate the marine geochemical cycle of the rare earth elements and their application as water-mass tracers.
Comparative yttrium and rare earth element chemistries in seawater Rare-earth distributions with a positive Ce anomaly in the western North Ariantic Ocean
- R H Byrne
- J H Lee
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- M P Bacon
- P G Brewer
- H J W Debaar
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- P G Brewer
- K Bruland
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The rare earth elements in seawater Rare-eanh distributions in the marine environment
- H Elderfield
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- E D Goldberg
- M Koide
- R A Schmitt
- R H Smith
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Lanthanide tetrad effect observed in marine environment Rare earth element patterns and crustal evolution -I. Australian post-Archean sedimentary rocks The behavior of rare ea@BULLET elements in seawater: Precise. determination of variations in the
- A Masuda
- Y Ikeuchi Nance
- S R Taylor Piepgras
- S B Jacobsen
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Rare earths in European shales: h redetermination Neutron activation analysis of elements in sea water
- M A Haskin
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- S Melson
- V T Bowen
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The geochemical ba!ance of the rare earth elements and neodymium isotopes in the oceans Trace element profiles from the GEOSECS II test station in the Sargasso Sea Oceanographic distributions of cadmium, zinc, nickel and copper in the north Pacific
- C I Bertram
- H Elderfield
- P G Brewer
- D W Spencer
- E Robertson Bruland
Bertram, C. I., and H. Elderfield, The geochemical ba!ance of the rare earth elements and neodymium isotopes in the oceans, Geochim. Coxmochirn. Acta 57, 1957-1986, 1993. Brewer, P. G., D. W. Spencer, and D, E. Robertson, Trace element profiles from the GEOSECS II test station in the Sargasso Sea, Earth Planet. Sci. Lett. 16, 11!-116, 1972. Bruland, K. W., Oceanographic distributions of cadmium, zinc, nickel and copper in the north Pacific, Earth Planet. Sci. Lett., 47, 176-198, 1980.
Yb) by carbonate ions
- J H Lee
- R H Byrne
Lee, J. H., and R. H. Byrne, Complexargon of trivalent rare earth
elements (Ce, Eu, Gd, Tb, Yb) by carbonate ions, Geochim,
Cosraochim. Acta 57, 295-302, 1993.