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X-Ray diffraction results for the study mine are mainly represented by two phases (phosphatic and non-phosphatic). First phase is represented by apatite (fluorapatite) which is the dominant. The second phase includes carbonate minerals; calcite, dolomite, evaporated mineral (gypsum), sulphide mineral (pyrite), in addition to quartz as a silicate mi...
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Petrography and whole-rock geochemical analysis of the Miocene Bhuban Formation exposed in the Jampui Anticline of
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intensity of paleo-weathering of the source rocks at that period is described in this work. The Bhuban sandston...
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... Silica, clayey and calcareous materials constitute the gangue matrix for phosphates of sedimentary origin. The most sedimentary calcareous phosphate rocks have significant amounts of carbonates, and are considered as carbonate-apatite or francolite (Jaballi et al. 2019;Abou El-Anwar, Abd El Rahim 2022). To date, not a lot of studies on phosphorites have been undertaken in the transboundary Tebessa El Gasrine collapsed basin. ...
The characterization of phosphorite features within specific North African sedimentary series remains incomplete. Hence, the primary aim of this research is to determine the composition of powder patterns and phosphatic allochem fragments within the Jebel Dhyr syncline, situated in northeastern Algeria. By focusing on this region, the study endeavors to investigate the mineralogical properties and geochemical aspects of Paleocene-Eocene phosphorites in the broader context of North Africa. The methodology employed encompasses geological, petrographic, geochemical, and mineralogical analyses of the rocks. To achieve this objective, we have employed various techniques including thin section analysis, atomic absorption spectrometry, and X-ray diffraction (XRD). The geological section across the Jebel Dhyr area has revealed a succession of horizontally layered rocks. These rocks consist of eight prominent phosphorite layers interspersed with carbonate formations. Additionally, occasional thin layers of flint can be observed within these carbonate layers. XRD analysis of the whole rock established the presence of apatite group minerals such as hydroxylapatite, fluroapatite, francolite, and dahllite. Other minerals identified include carbonates, quartz, zeolites, feldspar, clays, sulphides, and gypsum. XRD recordings on the phosphatic allochem grains (pellets, coprolites, intraclasts, and shark teeth) identified different mineral phases, with coprolites and pellets showing hydroxylapatite and fluorapatite, sometimes associated with dahllite, while granules of different forms revealed hydroxylapatite associated with fluorapatite or francolite. Teeth from the Jebel Dhyr phosphate beam showed the systematic presence of fluorapatite. This study provides valuable information for the comprehensive utilization of phosphorus resources in the Algeria-Tunisia border.
... e [72]. f [73]. g [74]. ...
In the present study, the immediate detection of rare-earth elements (REEs) in phosphorite deposits has been reported using laser-induced breakdown spectroscopy (LIBS). Numerous emission lines corresponding to the REEs such as lanthanum (La), cerium (Ce), neodymium (Nd), samarium (Sm), and ytterbium (Yb), have been detected in the emission spectra of phosphorite-induced plasma plume. For the quantitative analysis, we employed the calibration-free LIBS (CF-LIBS), and Energy Dispersive X-ray (EDX) spectroscopy techniques. The results obtained using the CF-LIBS technique show excellent agreement with that obtained by EDX. Besides principal component analysis (PCA) was employed by incorporating the LIBS spectral data of rare earth phos-phorite rocks samples containing La, Ce, Nd, Sm, and Yb emission lines. The first three PCs were observed using LIBS spectral data set showing a covariance (interpretation rate) up to 76.3%. This study suggests that LIBS yields a quick and very reliable qualitative and quantitative analysis of REEs in any geological ore sample.
... respectively), Fig. (5). Consequently, Th content increased from north (Safaga) to south (Qussier) which is conformed by Abou El-Anwar, et al., [46]. ...
... Some of the geochemical parameters can be utilized to evaluate the marine paleoredox conditions of sediments, such as redox-sensitive traces; V, Ni, Cr, Re, Mo, U, Cu, Cd, Se, Tl and Sb, as well as ratios of traces; Th/U, Ni/Co, V/Mo, V/Ni, V/(V + Ni) and V/(V + Cr), and the depletion content of Mn. The high contents of these redox-sensitive traces refer to anoxic conditions in sediments [49,12,18,16,43,46]. V, Mo, Zn, Cr, Zr, Cd, Sr, and rare earths; Y, As, Se, Sm and U in the studied area are higher than those of (UCC) and (PAAS), and Pb is lower than PAAS and higher than UCC (Table 1 and Fig. 5). ...
This chapter deals with some selected non-metallic ore deposits in North Africa that are hosted by a variety of rock lithologies with great diversity of type and age. Non-metallic ores in Africa north of the 18° N latitude were formed by a diverse variety of geological processes. These ores are hosted by different rocks that range in age from the Neoproterozoic (Nubian Shield in the east) until the Mesozoic (Atlas in the west). Also, some non-metallic ores are encountered in the Proterozoic rocks of the Mesozoic Atlas. The chapter provides an up-to-date review of new publications that dealt with a variety of non-metallic ores in igneous, metamorphic, and sedimentary host rocks from the Archean to recent. The chapter discusses the use of mineral fabrics, mineral chemistry, trace elements (including REEs), stable isotopes, fluid inclusions, paragenesis, and paragenetic sequence in order to decipher the ore genesis of some important non-metallic resources. They comprise a series of industrial minerals that are needed for the development of the North African countries in terms of modern technological applications, as well as to improve the state budgets and finally attain an acceptable standard of life in coherence with other developed parts of the world. The updated accounts include models of ore genesis for fluorite and barite ores that form either by igneous-related hydrothermal solutions or by sedimentary processes, including diagenesis and the effect of pedogenesis in terms of karst formation. The chapter also gives updates on new research of the important phosphate belt in North Africa, with an emphasis on the valuable content of by-products that are rich in radioactive elements and REEs. Other non-sedimentary resources of phosphates are also discussed, especially those occurring with alkaline felsic intrusions. Accounts of other representative non-metallic ores are also presented.
Soon for the security of phosphorus world supply, which comes primarily from non-renewable sources, the moderate carbonate phosphates will need further geochemical multidiscipline investigations to participate in the phosphorous supply chains necessary to increase human productivity. Dolomitic phosphates represented the main carbonate phosphate rocks of the Upper Member of Duwi Formation, at Um Queih Mine, South-Western Quseir, that phosphate can be classified as intermediate grade phosphate ore. It was enriched in V, Ni, Mo, U, Cu, Cr, Cd, Co as well as Zn and their ratios indicated that the deposition occurred in anoxic environment (reducing conditions). Mineralogical investigations indicated that the studied phosphorites are composed of two main mineral phases; fluorapatite and non-phosphatic minerals (dolomite, calcite, pyrite, gypsum, and quartz). The petrographic examination revealed that these phosphorites are composed of phosphatic lithoclasts, phosphatic bioclasts, opaques, and quartz grains embedded in a cryptocrystalline phosphatic matrix. The parent rocks of the studied phosphorites represented by basaltic mafic provenance were affected by low chemical weathering and deposited under marine anoxic environment. The mineralogical and geochemical characteristics indicated that the studied phosphorites deposited in marine anoxic condition. The weathering of these rocks can be harmful to the surrounding environment owing to its content of pyrite and potentially toxic elements (PTEs), the EF (enrichment factor) gives extremely high enriched with Mo, Cd, and Se.
Phosphate deposits are found in the Khormuj anticline at the end of the Folded Zagros Zone of Iran and are enriched in REE and trace metals. Field surveys, petrography, X-ray diffraction and whole-rock geochemistry were used to determine the petrogenesis of these phosphate deposits and evaluate the mechanisms of trace metal enrichment. Khormuj anticline phosphate layers are hosted by carbonate rocks of the Pabdeh Formation (Lower Paleocene–Oligocene). The phosphatic layers are composed of phosphorus grainstone–packstone with microfossils and contain green glauconite. Whole-rock compositions of phosphates indicate a minimal detrital component and enrichment of HREE and U. These elements are not enriched in the limestone units that overlie and underlie the phosphate layers. Overall, the textures and trace-element compositions of phosphate layers are interpreted to represent accumulation on a basin margin carbonate ramp, in the reduced and suboxic-to-anoxic zone, with low detrital input but occasional high-energy erosional events. Upwelling played a fundamental role in the deposition of the sandy glauconite-bearing phosphate layers. Phosphate mineralization has syngenetic, diagenetic, and epigenetic components. Positive correlations between P2O5 and REE, U and other trace elements suggest that cation substitution into carbonate fluorapatite and not ion adsorption is the dominant mechanism for metal enrichment in these phosphates. REE patterns in these phosphate layers show strong negative Ce anomalies, positive Eu and Y anomalies, and high La/Yb ratios (> 10). Yttrium versus (La/Nd)N ratios are consistent with seawater and have been affected by diagenesis. These elevated ratios suggest that the phosphates are relatively enriched in both the LREE and HREE. This enrichment is related to their marine origin, and weathering had no effect on the phosphate horizons. This research shows that marine phosphates have a high potential to preferentially fractionate the HREE and U and could represent a potential source of these metals in the future.
Twenty-six samples involved CFA (carbonate fluor-apatite) and intercalated marl were collected from four outcrops of the Campanian phosphorites horizon extending along 9km of a minable NE-SW side wall of the Abu Tartur Plateau. Samples were analyzed chemically using XRF (x-ray fluorescence) and ICP-OES (Inductively coupled plasma optical emission spectrometry) techniques for measuring oxides, trace elements, and REE (Rare earth elements) for deducing their implication for the paleo-depositional environment. The CFA samples show an average compositional richness in major oxides of CaO (42.23wt%) and P2O5 (27.22wt%) with a considerable amount of F (2.75%). Whilst the main average composition of the intercalated marl is SiO2 (54.17wt%) and CaO (10.58wt%). The geochemical classification of this marl shows a type of Fe-sand (Ferro-magnesium potassic sandstone). The P2O5 in the marl samples does not exceed 3.46wt%. Calculation of the CaO/MgO molar ratio of studied samples reveals evidence of the dolomitization process took place, making a conversion of approximately 65.73% of the entire CFA to be dolomitic- and highly dolomitic-francolite may occur over a long time post of the Campanian age. CFA samples have an amount of Fe2O3 ranging from 3.15wt% to 5.84wt% (average 4.31wt%) whereas Fe2O3 in the marl samples range from 3.81wt% to 6.03wt% (average 4.41wt%). The origin of iron is attributed to being delivered by an ancient river system laden from hot, humid chemically weathered (laterite) soils into the basin simultaneously with the dolomitization process. Less saline mixed water is the suggested medium where dolomitization processes occur based on Rb/Sr and Sr/Ba ratios. The normalized REE pattern of the base, middle and top parts of the CFA samples show a similarity of fingerprint patterns of near-shore and margin-marine of either bottom seawater and shallow- to deep- pore-water below the SWI (sediment-water interface). Dysoxic to oxic depositional environments of the marginal shelf are established based on measured trace elements ratios of V/Cr, Ni/Co and V/(V+Ni). The accumulation rate of P shows a progressively increasing trend toward the NE direction of favourable P depositional conditions. The results of the Ce/Ce* and Pr/Pr* anomalies show no- to +ve Ce/Ce* lie between 0.93 and 1.45 (average 1.04) and the Y/Ho ratio lie between 23.43 and 87.75 (average 51.63) which is attributed to depositional sets within the shelf margin of suboxic to anoxic pore-water chemistry conditions at bottom seawater below the sediment-water interface. The fingerprint shape of the REE patterns and the richest of HREE (Heavy rare earth elements) of the studied CFA samples reflect the chemistry of the shallow to the deep pore-water flux of suboxic-anoxic sulfidic characters.
Phosphate deposits are found in the Khormuj anticline at the end of the Folded Zagros Zone of Iran and are enriched in REE and trace metals. Field survey, petrography, X-ray diffraction and whole-rock geochemistry were used to determine the petrogenesis of these phosphate deposits and evaluate the mechanisms of trace metal enrichment. Khormuj anticline phosphate layers are hosted by carbonate rocks of the Pabdeh Formation (Lower Paleocene-Oligocene). The phosphatic layers are composed of phosphorus grainstone–packstone with microfossils and contains green glauconite. Whole-rock compositions of phosphates indicate a minimal detrital component and enrichment in U and HREE. These elements are not enriched in the limestone units that overlie and underlie the phosphate layers. Overall, the textures and trace element compositions of phosphate layers are interpreted to represent accumulation on a basin margin carbonate ramp, in the reduced and suboxic-to-anoxic zone, with low detrital input but occasional high-energy erosional events. Upwelling process played a fundamental role in the deposition of the sandy glauconite-bearing phosphate layers. Phosphate mineralization has syngenetic, diagenetic, and epigenetic components. Positive correlations between P 2 O 5 and REE, U and other trace elements suggest that cation substitution into carbonate fluorapatite and not ion adsorption is the dominant mechanism for metal enrichment in these phosphates. REE patterns in these phosphate layers show strong negative Ce anomalies, positive Eu and Y anomalies and high La/Yb ratios (> 10). Yttrium versus (La/Nd) N ratios are in the seawater range and have been affected by diagenesis process. These elevated ratios suggest that the phosphates are relatively enriched in both the LREE and HREE. This enrichment is related to their marine origin, and weathering had no effect on the phosphate horizons. This research show that marine phosphates have high potential to preferentially fractionate the HREE and U and could represent a future source of these metals.
