Fig 11
Source publication
Constraints on density as a function of pressure, temperature, and composition are crucial to understand isostatic movements
during geodynamic processes. Here, we provide a systematic series of density diagrams extracted from thermodynamic calculations
for a variety of crustal compositions within a wide P–T range. We quantify systematic density cha...
Context in source publication
Context 1
... if the basalt is compared to a more Fe-and Mg-rich composition, e.g., mix14p, the difference in density is reduced to 4.8%. Massonne et al. (2007) showed that pelitic rocks can get very dense at high to ultrahigh pressures, which is confirmed by our results. We also compute densities for a Fe-and Al-rich natural rock, the Fjørtoft gneiss ( Fig. 11; Table 4), which was found to be the densest meta-pelite by Massonne et al. (2007) at ultrahigh-pressure conditions. The Fjørtoft gneiss yields 3,304 kg/m 3 at 800°C and 2.5 GPa, and the density difference between mafic and pelitic rocks is reduced to 3.7%. At 700°C and 1.2 GPa, the MORB has a density of 3,111 kg/m 3 and a water ...
Similar publications
An experimental investigation of phase relations in synthetic compositions simulating natural metasediments has been carried out to determine the relative stability of cordierite and garnet as a function of pressure, temperature and chemical composition. Anhydrous solid-solid equilibria have been studied at temperatures of 800-1200 °C and pressures...
Citations
... The density of rocks is a function of pressure, temperature, and chemical composition (Duesterhoeft et al., 2014;Semprich et al., 2010). Key metamorphic mineral reactions and phase transitions can therefore produce significant jumps in density within the crust, causing instability. ...
... Other increases in density are associated with garnet and staurolite formation. The modeling result of density is well consistent with systematic density simulation of metapelite in a large ranges of whole rock compositions (Semprich et al., 2010). The generation of partial melts due to reaction between plagioclase, sillimanite and quartz will dramatically decrease bulk-rock density. ...
... To simulate the upper crust, we used natural dry quartz sand and layers of artificially dyed quartz sand to function as deformation markers in model A, and white corundum sand interlayered with black corundum sand in model B. The thickness of the experiment was 4 cm (Table 1), and the granular material was sieved into the experimental apparatus from an approximate height of 30 cm. The used quartz sand Table 1 Analogue modeling material properties, parameters and dimensionless values (Buck, 1991;Gomes et al., 2019;Herzberg et al., 1983;Lücke et al., 2010;McKenzie, 1978;Semprich et al., 2010;Simiyu and Keller, 2001;Weijermars et al., 1993;Yuan et al., 2020). had rounded grains, with a size <30 μm, density (ρ) of 1440 kg/m 3 , internal friction angle (φ) of 32.6 • , internal friction coefficient (μ 0 ) equal to 0.64, and cohesion (C 0 ) of 163 Pa (Venâncio and Alves da Silva, 2019, See Table 1). ...
... При давлениях и температурах, характерных для нижней части континентальной коры, многие из залегающих в ней пород, такие как амфиболиты, метапелиты, габбро и др., оказываются метастабильными ( [19] и др.). Их переход в более высокоградные фации может сопровождаться значительным уплотнением (до 10-15% и более) ( [18] и др.). Наиболее значительное повышение плотности обычно связывается с переходом габброидов в гранатовые гранулиты и эклогиты. ...
... На древней литосфере с установившимся термическим режимом единственная известная причина такого уплотнения -проградный метаморфизм в земной коре ( [18,19] и др.). Наиболее вероятным является переход базитов нижней коры в более плотные метаморфические фации. ...
В центральной части Восточно-Европейской платформы расположен осадочный бассейн Московской синеклизы. Он детально разбурен и характеризуется исключительно высокой степенью изученности. В девонское время после длительного периода размыва здесь началось погружение коры, сильно неоднородное на площади. На древней литосфере большой мощности такой режим погружения мог реализовываться только в связи с уплотнением пород в нижней части коры в результате проградного метаморфизма, катализированного инфильтрацией мантийных флюидов. Об их поступлении в литосферу Восточно-Европейской платформы свидетельствует широкое проявление в девоне базитового и кимберлитового магматизма. Распределение погружения по площади синеклизы сильно изменялось за времена в несколько миллионов лет. Это указывает на соответствующие изменения скорости притока в древнюю литосферу глубинных флюидов, а также на их высокую поверхностную активность. Данное свойство флюидов обеспечило их быструю инфильтрацию в мантийную литосферу и поступление в кору на всей площади синеклизы. Длительное поступление в
континентальную литосферу глубинных флюидов, часто изменявшееся во времени и в пространстве, представляет собой новое явление, не связанное с крупномасштабной конвекцией в мантии и с подъемом крупных плюмов. Оно может быть причиной образования многих осадочных бассейнов во внутриплитных областях на континентах.
... Previous studies have successfully constrained the phase relations and gravity stability of arc crust (Behn & Kelemen, 2006;T. Chapman et al., 2017;De Paoli et al., 2012;Jull & Kelemen, 2001) and lower continental crust (Hacker et al., 2015;Hetényi et al., 2007;Semprich et al., 2010;Sobolev & Babeyko, 1989). However, the effects of compositional heterogeneity, partial melting, and rheology on crustal stability still lack systematic investigations. ...
... Crustal density has been proven to be very sensitive to bulk SiO 2 content, which directly controls the proportion of low-density quartz in quartz-saturated rocks (De Paoli et al., 2012;Semprich et al., 2010). To constrain the minimum silica value required to maintain mafic lower crust neutral buoyancy, we constructed a Python code using the Theriak-Domino (De Capitani & Brown, 1987) program to calculate the densities of global mafic lower crustal xenoliths at P = 21 kbar and T = 900 C (Figure 8a). ...
... Therefore, we predict that only limited mafic rocks appear gravitationally stable at ≥70 km if T Moho = 900 C ( Figure 11). Previous studies indicate that intermediatefelsic rocks have densities lower than the mantle at HP to ultrahigh-pressure (UHP) conditions due to the high proportion of light quartz or coesite (e.g., Massonne, 2009;Semprich et al., 2010;Tassara, 2006). Our modelling also shows that rock density is negatively correlated with bulk SiO 2 (Figure 8a,b), confirming the low densities of silicarich rocks. ...
Orogenically thickened lower crust is the key site of crustal differentiation, crustal deformation, and Moho modification. However, the composition of thickened lower crust is still highly debated. Here, we calculate a set of pseudosections with mafic lower crust compositions in the Na2O–CaO–K2O–FeO–MgO–Al2O3–SiO2–H2O–TiO2–O2 (NCKFMASHTO) system. Our modeling results show that the maximum thickness of the mafic lower crust increases with the Moho temperature (TMoho). In addition, the lithologies of stable mafic crust are characterized by medium‐pressure (MP) to high‐pressure (HP) granulites at 40–50 km, HP granulites and garnet‐omphacite granulites at 50–60 km, and garnet‐omphacite granulites at 60–70 km. Under the Pamir geothermal conditions, mafic rocks with high SiO2 (>50.2 wt%), XMg (>0.70), XCa (>0.49), or low XAl (<0.11) could be stable at 70 km; however, only ~10% of global mafic granulite xenoliths lie within this compositional range. Further modeling indicates that if TMoho reaches 900–1000 °C, neither the lower crust nor the upper mantle has significant strength relative to the upper crust, and that only ~5–37% of mafic materials are gravitationally stable at 70 km. This implies that the base of doubly thickened (70 km) crust is dominated by intermediate‐felsic rocks, consistent with the low Vp and Vp/Vs values seismically observed in young orogenic crustal roots. Thus, most mafic materials at >70 km could delaminate into the deep mantle. Our results provide insights on the formation of extremely thick crust with a predominantly intermediate‐felsic base and the crustal thickness variation in continental collision zones.
... In particular, numerical and analog experiments are used as prominent methods to simulate the dynamics of delamination (Gögüş and Ueda, 2018). Of these studies, the density behavior occurring during the delamination process has also been investigated intensively following thermodynamic (Semprich et al., 2010), seismic and/or tomography (Matchette-Downes et al., 2019), and numerical simulations . However, few studies have systematically illuminated the issue of delamination from the perspective of eclogite density. ...
Tibet, which is characterized by collisional orogens, has undergone the
process of delamination or convective removal. The lower crust and mantle
lithosphere appear to have been removed through delamination during orogenic
development. Numerical and analog experiments demonstrate that the
metamorphic eclogitized oceanic subduction slab or lower crust may promote
gravitational instability due to increased density. The eclogitized
oceanic subduction slab or crustal root is believed to be denser than the
underlying mantle and tends to sink. However, the density of eclogite under
high-pressure and high-temperature conditions as well as density differences from
the surrounding mantle are not preciously constrained. Here, we offer new
insights into the derivation of eclogite density with a single experiment to
constrain delamination in Tibet. Using in situ synchrotron X-ray diffraction
combined with a diamond anvil cell, experiments focused on minerals (garnet,
omphacite, and epidote) of eclogite are conducted under simultaneous
high-pressure and high-temperature conditions, which avoids systematic
errors. Fitting the pressure–temperature–volume data with the third-order
Birch–Murnaghan equation of state, the thermal equation of state (EoS)
parameters, including the bulk modulus (KT0), its pressure derivative
(KT0′), and the thermal expansion coefficient (α0),
are derived. The densities of rock-forming minerals and eclogite are modeled
along with the geotherms of two types of delamination. The delamination
processes of subduction slab break-off and the removal of the eclogitized
lower crust in Tibet are discussed. The Tibetan eclogite, which contains
40 vol %–60 vol % garnet and 44 %–70 % eclogitization, can promote
the delamination of slab break-off in Tibet. Our results indicate that
eclogite is a major controlling factor in the initiation of delamination. A
high abundance of garnet, a high Fe content, and a high degree of
eclogitization are more conducive to instigating the
delamination.
... The density increase provided by metamorphic changes of gabbro to denser granulite and eclogite was invoked previously (Artyushkov et al., 2014) to account for the subsidence of several other basins which formed without significant extension: Cis-Caspian, South Caspian, North Barents, North Chukchi, and the Gulf of Mexico. The same mechanism was also suggested for the Barents Sea (Semprich et al., 2010;Gac et al., 2012;Artemieva and Thybo, 2013), while Mooney and Kaban (2010) found that heavy eclogite may occur beneath the Gulf of Mexico. ...
The western part of the large Amerasia Basin in the Arctic Ocean comprises the smaller basins of Podvodnikov and Makarov. Judging by the sedimentary structure and the crustal subsidence history, both basins were developed on the continental crust despite their 3–4 km water depths. By the early Miocene, prior to the rapid formation of the basins, the crustal surface had been close to the sea level for a long time. Lithospheric stretching had a minor input to the subsidence, which was rather driven mainly by the prograde metamorphism of gabbro in the lower crust and its transformation into denser eclogite. The mechanism of subsidence associated with the metamorphic transformation from gabbro to eclogite implies that high-velocity eclogite belongs to the lower continental crust metamorphosed under the effect of mantle fluids. This idea undermines the seismic and gravity basin models that commonly attribute mafic eclogite to the sub-Moho lithospheric mantle on the basis of P-wave velocities similar to those in peridotite and interprets the crust beneath the Podvodnikov and Makarov basins as thin continental and oceanic crustal types, respectively.
... In-situ fidelity coring of deep rock with different burial depth is the pioneering science. As it is known, the internal environment of the crust is extremely complicated, and even small changes in whole-rock composition can lead to significant changes in mineralogy at different depths, temperatures and pressures within the crust, and change the density and hardness of the rock [62]. This hardness distribution is very uneven. ...
Concept generation plays a critical role in product design especially in the early design phase when functional requirements are either uncertain or partially known. To cope with the uncertainty imposed by the varying work environment, resilient design has often been called upon to leverage system capacity from the perspective of functional requirements. While the resilient design has been advanced recently, how to design a resilient product structure so to accommodate more functional requirements at the conceptual design phase remains challenging. To tackle this issue, we propose a methodology to support resilient conceptual design using functional decomposition and conflict resolution. To reduce the impact imposed by potential issues and uncertain environments, the overall system functional requirements are defined based on five principles of resilient design. The redundant conceptual scheme that meets functional requirements is given resilience through functional decomposition and conflict resolution. A case study of the conceptual design of a hard rock coring structure present to demonstrate the feasibility of the proposed approach. The results yielded have suggested that the proposed approach can not only support resilient conceptual design, but also leverage design reliability and robustness under uncertainty, especially in terms of varying work environments.
... In petrological studies, geotherms T(z) are often approximated by linear or close to linear functions (e.g., Schreyer, 1995;Semprich et al., 2010;Spear, 1993). Using the data on rocks now located at the surface, temperature gradients dT/ dz = 20 and 30 °C/km are often taken for the Archean crust (e.g., Figs. ...
... However more important are not the density changes under diaphthoresis of individual minerals but the densities of primary and secondary polymineralic parageneses under the assumption of an isochemical character of diaphthoresis for all oxide components except H 2 O. Systematic calculations based on the examples of typical rocks have been done by (Massonne, 2009(Massonne, , 2015Massonne and Calderon, 2008;Massonne and Toulkeridis, 2012;Massonne and Willner, 2008;Massonne et al., 2007;Semprich et al., 2010). The results for a specifi c rock are shown in P-T diagrams contoured by isochores in g/cm 3 in the interval of P from 0.2 to 4 GPa, and T from 300 to 1000 °С. ...
... Considerable progress has been achieved by (Semprich et al., 2010) who calculated phase diagrams for some rocks of continental crust down to P = 0 and T = 500 °С. It has been found that under the increasing P a considerable density increase can occur not only in mafi c rocks such as gabbro but in silicic rocks too, e.g., in metapelites. ...
Precambrian cratons cover about 70% of the total continental area. According to a large volume of geomorphological, geological, paleontological, and other data for the Pliocene and Pleistocene, these cratons have experienced a crustal uplift from 100–200 m to 1000–1500 m, commonly called the recent or Neotectonic uplift. Shortening of the Precambrian crust terminated half a billion years ago or earlier, and its uplift could not have been produced by this mechanism. According to the main models of dynamic topography in the mantle, the distribution of displacements at the surface is quite diff erent from that of the Neotectonic movements. According to seismic data, there is no magmatic underplating beneath most of the Precambrian cratons. In most of cratonic areas, the mantle lithosphere is very thick, which makes its recent delamination unlikely. Asthenospheric replacement of the lower part of the mantle lithosphere beneath the Precambrian cratons might have produced only a minor part of their Neotectonic uplifts. Since the above mechanisms cannot explain this phenomenon, the rock expansion in the crustal layer is supposed to
be the main cause of the recent uplift of Precambrian cratons. This is supported by the strong lateral nonuniformity of the uplift, which indicates that expansion of rocks took place at a shallow depth. Expansion might have occurred in crustal rocks that emerged from the lower crust into the middle crust with lower pressure and temperature after the denudation of a thick layer of surface rocks. In the dry state, these rocks can remain metastable for a long time. However, rapid metamorphism accompanied by expansion of rocks can be caused by infi ltration of hydrous fluids from the mantle.
... Âìåñ òå ñ òåì îñòà åò ñÿ ìíî ãî íå îïðå äåë¸ííîñ òåé â îò íî øå íèè ãëó áèí íûõ ìå õà íèç ìîâ, îá óñëî âèâ øèõ ðàç âè òèå ýòèõ ñòðóêòóð. Ïðåä ëî aeåí íûå ðà íåå ìî äå ëè áàñ ñåé íî îá ðà çîâà íèÿ [1,11,12,19] íå îá ú ÿñ íÿ þò áåç ðèô òî âîå çàëî aeå íèå ðàñ ñìàò ðè âà å ìûõ áàñ ñåé íîâ íà äðåâ íåé ïàñ ñèâ íîé ìà òå ðè êî âîé îêðà è íå è ïðî èñ õîae äå íèå èõ ñïå öè ôè ÷åñ êîé îâàëü íîé ôîð ìû. ...
A dual model of the Paleozoic basins development, disposing on the Late Proterozoic (Pan-African) and the Early Proterozoic (Eburnean) crust, has been proposed. The formation of the first group basins is connected with the subsiding of the sections of the cooling gneissic-domes of«rejuvenated» (Early Precambrian but tectonically reworked at the end of the Proterozoic) Pan-African crust. Accordingly, the development of the second group basins is a result of the Precambrian deep sited (mantle) magmatic chambers cooling and subsiding together with the sites of the old lithosphere, covering them. The manifestation of the Vendian volcanic units on Anti-Atlas, Ugarta, Regibat-Eglab uplifts is the most possible evidence of the mantle magmatic activity, which could create those chambers.
... The body was probably emplaced during the Caledonian Orogeny (Ritzmann & Faleide 2007) as the eastern margin of the Loppa High and Hammerfest Basin is believed to overlap the Caledonian suture zone (Torsvik & Cocks 2017). Depending on local conditions of pressure and temperature, such mafic bodies may be subject to metamorphic phase changes and associated density changes (Semprich et al. 2010). Compression may cause tectonic overpressure leading to densification and events associated with lithosphere heating (such as rifting or a plume) may supply enough heat to trigger phase changes to produce lighter mineral assemblages Burov & Cloetingh 2009;Cloetingh & Burov 2011). ...
... Compression may cause tectonic overpressure leading to densification and events associated with lithosphere heating (such as rifting or a plume) may supply enough heat to trigger phase changes to produce lighter mineral assemblages Burov & Cloetingh 2009;Cloetingh & Burov 2011). Such density changes may in turn cause vertical surface deformation (Kaus et al. 2005;Semprich et al. 2010;Gac et al. 2013Gac et al. , 2014. ...
... Composition of the mafic body. We modelled the pressuretemperature-dependent density of the mafic body assuming a wet mafic gabbroic composition characterized by low SiO 2 content (Rudnick & Fountain 1995;Semprich et al. 2010) (Fig. 4c). Minor differences in assumed composition would, however, result in considerable variations in calculated densities within the mafic body at given changes in pressure and temperature (e.g. ...
The Loppa High area has been subject to several events of uplift and subsidence from the Late Paleozoic to Present. The driving mechanisms behind the vertical movements, however, are not fully understood. We propose that uplift and subsidence were influenced by the combination of density changes caused by metamorphic phase changes in a 90 × 140 km wide mafic lower crustal body below the Loppa High and local (rift-related) and far-field stress. Through a numerical modelling approach we analyse the tectonically induced variations in pressure and temperature in the lower crust, their influence on phase changes in the mafic body and the affiliated vertical movements. Results show that (1) densification of the mafic body caused by far-field compression associated with the late Triassic westward translation of Novaya Zemlya could cause surface subsidence, (2) heat and fluid influx provided by early Cretaceous rifting could trigger density reduction and surface uplift and (3) the present-day geometry of the Loppa High as observed in seismic data can be reproduced by combining the modelled effect of rift flank uplift and phase changes in the mafic body. Phase change-driven vertical movements may also have affected other structural highs in the western Barents Sea, including the Stappen High.
