The Yelapa-Chimo Metamorphic Complex forms part of the Jalisco Block in western Mexico and exposes a wide range of Early Cretaceous metamorphic rocks;such as paragneiss,orthogneiss,amphibolites,and migmatites.However,...The Yelapa-Chimo Metamorphic Complex forms part of the Jalisco Block in western Mexico and exposes a wide range of Early Cretaceous metamorphic rocks;such as paragneiss,orthogneiss,amphibolites,and migmatites.However,the pressure-temperature(P-T)conditions of metamorphism and partial melting remain poorly studied in the region.To elucidate metamorphic P-T conditions,phase equilibrium modelling was applied to two sillimanite-garnet paragneisses,one amphibole-orthogneiss,and one amphibolite.Sillimanite-garnet paragneisses exhibit a lepidoblastic texture with a biotite+sillimanite+kyanite+garnet+quartz+plagioclase+K-feldspar mineral assemblage.Amphibole-orthogneiss and amphibolite display a nematoblastic texture with an amphibole+(1)plagioclase+quartz+(1)titanite assemblage and an amphibole+(2)plagioclase+(2)titanite+ilmenite retrograde mineral assemblage.Pseudosections calculated for the two sillimanite-garnet paragneiss samples show P-T peak conditions at~6-7.5 kbar and~725-740℃.The results for amphibole-orthogneiss and the amphibolite yield P-T peak conditions at~8.5-10 kbar and~690-710℃.The mode models imply that metasedimentary and metaigneous units can produce up to~20 vol%and~10 vol%of melt,respectively.Modelling within a closed system during isobaric heating suggests that melt compositions of metasedimentary and metaigneous units are likely to have direct implications for the petrogenesis of the Puerto Vallarta Batholith.Our new data indicate that the Yelapa-Chimo Metamorphic Complex evolved through a metamorphic gradient between~23-33℃km^-1and the metamorphic rocks formed at depths between~22 km and~30 km with a burial rate of~2.0 km Ma^-1.Finally,the P-T data for both metasedimentary and metaigneous rocks provide new constraints on an accretionary framework,which is responsible for generating metamorphism and partial melting in the YelapaChimo Metamorphic Complex during the Early Cretaceous.展开更多
Zircon is a common accessory mineral in various rocks,especially in the crustal ones.It is the best mineral for U-Pb dating.Meanwhile,trace elements and isotopes of the mineral can also provide much information concer...Zircon is a common accessory mineral in various rocks,especially in the crustal ones.It is the best mineral for U-Pb dating.Meanwhile,trace elements and isotopes of the mineral can also provide much information concerning the formation and evolution of rocks.There are a growing number of reports of zircon existing in mantle peridotite.However,it is generally considered that zircon is unlikely crystallized in ultrabasic rocks due to SiO_(2)-unsaturation.In this paper,the SiO_(2) activity and zircon/baddeleyite transition curve at different conditions were calculated through thermodynamic phase equilibrium modeling,to reveal the main factors affecting the SiO_(2) activity and the stability of zircon/baddeleyite in ultrabasic and basic rocks,especially in mantle peridotite.These results provide a thermodynamic basis for interpreting the genesis and significance of zircon in mantle rocks.That is,the SiO_(2) activity is mainly controlled by stable mineral assemblages and temperature-pressure conditions.The orthopyroxene+olivine assemblage in peridotite as an effective buffer restricts the SiO_(2) activity in a relatively high range with a small variation.The upper temperature limit of zircon can reach more than 1500℃ with this mineral assemblage.During the low-temperature serpentinization of peridotite,the replacement of olivine and pyroxene by serpentine can result in a significant decrease of SiO_(2) activity,and baddeleyite can be stabilized at<530℃ and<2.7 GPa.When peridotite is strongly metasomatized by the SiO_(2)-bearing fluid,the addition of SiO_(2) can increase its activity and make zircon stable at low temperatures.The SiO_(2) activity in ultrabasic-basic rocks is not only positively correlated with the SiO_(2) content but also negatively correlated with the Ca and Na contents of rocks.This is because Ca and Na preferentially combine with Si and Al to form Si-rich minerals,such as clinopyroxene and feldspar.This process will consume excessive SiO_(2),decreasing the SiO_(2) activity.This may be the reason why zircon can be found in ultrabasic rocks,while baddeleyite can exist in some basic and alkaline rocks.The thermodynamic modeling can also reasonably explain the mutual transformation between zircon and baddeleyite in ultrabasic-basic rocks.Our results indicate that zircon can exist stably in mantle peridotite in a wide range of temperature-pressure conditions and its formation is related to melt/fluid metasomatism.That is,the presence of zircon in mantle peridotite is an important information carrier of crust-mantle interaction for deep material cycling.展开更多
The granulitized eclogites from the Luliangshan terrane of the North Qaidam UHP metamorphic belt occur as lenses within pelitic gneisses and orthogneisses. Combined petrologic data and phase equilibrium modeling indic...The granulitized eclogites from the Luliangshan terrane of the North Qaidam UHP metamorphic belt occur as lenses within pelitic gneisses and orthogneisses. Combined petrologic data and phase equilibrium modeling indicate a multi-stage metamorphic history of the granulitized eclogites:(1) an earlier eclogite facies metamorphism(P>18.5 kbar, T> 830℃) is deduced from omphacite relics in the matrix and rare omphacite inclusions within garnet. The possible assemblage is garnet+omphacite+rutile+ quartz;(2) the early stage of high pressure granulite facies assemblages(garnet+clinopyroxene+ plagioclase+rutile+quartz+liquid) developed in the early decompression process has a P-T regime of 17.5 kbar and 852–858 ℃, constrained by plagioclase and clinopyroxene inclusions in garnet. The late stage of high pressure granulite assemblages(garnet+clinopyroxene+amphibole+plagioclase+rutile+quartz+liquid) records an isothermal decompression process with the pressure successively declining from 17.5 to 14.7 kbar and to 11.3 kbar at 858 ℃;(3) the later medium pressure granulite facies assemblage(garnet+ orthopyroxene+clinopyroxene+amphibole+plagioclase+ilmenite+liquid+quartz) indicates a drop in pressure and rise in temperature at P-T conditions of 7.6–7.7 kbar and 878–883 ℃;(4) retrogressive amphibolite facies stage, which is represented by amphibole+plagioclase kelyphitic rims around garnet, formed under conditions of <5 kbar and <650 ℃. The preservation of medium pressure granulite facies assemblage and the garnet composition feature constrain a following isobaric cooling path during late exhumation. This process suggests a clockwise P-T path and indicates that the granulitized eclogites record a high grade "Barrovian" metamorphic overprint at the middle-lower crust during exhumation. The present data show that the Luliangshan terrane is a "hot" HP-UHP terrane.展开更多
In contrast to the traditional interpretation of shear bands in sand as a bifurcation problem in continuum mechanics,shear bands in sand are considered as high-strain phase(plastic phase) of sand and the materials out...In contrast to the traditional interpretation of shear bands in sand as a bifurcation problem in continuum mechanics,shear bands in sand are considered as high-strain phase(plastic phase) of sand and the materials outside the bands are still in low-strain phase(elastic phase),namely,the two phases of sand can coexist under certain condition.As a one-dimensional example,the results show that,for materials with strain-softening behavior,the two-phase solution is a stable branch of solutions,but the method to find two-phase solutions is very different from the one for bifurcation analysis.The theory of multi-phase equilibrium and the slow plastic flow model are applied to predict the formation and patterns of shear bands in sand specimens,discontinuity of deformation gradient and stress across interfaces between shear bands and other regions is considered,the continuity of displacements and traction across interfaces is imposed,and the Maxwell relation is satisfied.The governing equations are deduced.The critical stress for the formation of a shear band,both the stresses and strains inside the band and outside the band,and the inclination angle of the band can all be predicted.The predicted results are consistent with experimental measurements.展开更多
Vapor-liquid phase equilibrium data including composition,densities,molar volume and equilibrium constant of isobutanol in supercritical carbon dioxide from 313.2K to 353.2K were measured in a variable-volume visual c...Vapor-liquid phase equilibrium data including composition,densities,molar volume and equilibrium constant of isobutanol in supercritical carbon dioxide from 313.2K to 353.2K were measured in a variable-volume visual cell.The properties of critical point were obtained by extrapolation.The results showed that critical temperature,critical pressure and critical compressibility factor of CO2-isobutanol system decreased with the increase of critical CO2 content.The phase equilibrium model was established by Peng-Robinson equation of state and van der Waals-2 mixing regulation,and model parameters were determined by optimization calculation of nonlinear least square method.The correlation between calculated values and the experimental data showed good agreement.展开更多
The Isin g model is used to investigate (0001), (10^-10), (10^-11) interfaces, etc. , for the hcp lattice. The system studied here have the nearest-neighbor (NN) and next-nearest-neighbor (NNN) pair interactions. The ...The Isin g model is used to investigate (0001), (10^-10), (10^-11) interfaces, etc. , for the hcp lattice. The system studied here have the nearest-neighbor (NN) and next-nearest-neighbor (NNN) pair interactions. The interface energy, interface phase transition at zero temperature and roughening temperature are used to analyse the properties of these interfaces. As a special case of the hcp crystals, we give the equilibrium shape of the He crystal at T=OK.展开更多
The Dahongshan Group,situated at the southwestern margin of the Yangtze Block,represents a geological unit characterized by relatively high-grade metamorphism in the region.This paper investigates the garnet-biotite s...The Dahongshan Group,situated at the southwestern margin of the Yangtze Block,represents a geological unit characterized by relatively high-grade metamorphism in the region.This paper investigates the garnet-biotite schist from the Laochanghe Formation of the Dahongshan Group,employing an integrated approach that includes petrological analysis,phase equilibrium modeling,and zircon U-Pb dating.The schist is mainly composed of garnet,biotite,plagioclase,quartz,rutile,and ilmenite.Phase equilibrium modeling revealed the peak metamorphic conditions of 8-9 kbar and 635-675°C.By further integrating the prograde metamorphic profile of garnet and geothermobarometric results,a clockwise P-T metamorphic evolution path is constructed,which includes an increase in temperature and pressure during the prograde stage.LA-ICP-MS zircon U-Pb dating and zircon Ti thermometry constrains the post-peak metamorphic age of 831.2±7.2 Ma.Integrated with previously reported results,it is revealed that the southwestern margin of the Yangtze Block experienced a large-scale regional metamorphism during the Neoproterozoic(890-750 Ma),which is related to the collisional orogenic process.This may be associated with the late-stage assembly of the Rodinia supercontinent or with local compression and subduction processes during the breakup of the Rodinia supercontinent.展开更多
研究区位于大别造山带晓天—磨子潭断裂附近(图1)。晓天—磨子潭断裂是北大别杂岩带和北淮阳带之间的边界断裂,部分研究者认为该断裂带为华北板块和扬子板块之间的缝合线以及大别山超高压变质岩折返的重要边界(Faure et al.,1999;徐树桐...研究区位于大别造山带晓天—磨子潭断裂附近(图1)。晓天—磨子潭断裂是北大别杂岩带和北淮阳带之间的边界断裂,部分研究者认为该断裂带为华北板块和扬子板块之间的缝合线以及大别山超高压变质岩折返的重要边界(Faure et al.,1999;徐树桐等,2002),但对此仍存在较大争议。展开更多
The binary solid-liquid equilibrium of Dimethyl Terephthalate （DMT）, Dimethyl lsophthalate （DMI） and Dimeth- yl Phthalate （DMP） was investigated by experiment and differential scanning calorimetry （DSC）. The r...The binary solid-liquid equilibrium of Dimethyl Terephthalate （DMT）, Dimethyl lsophthalate （DMI） and Dimeth- yl Phthalate （DMP） was investigated by experiment and differential scanning calorimetry （DSC）. The result demonstrated DMT/DMI and DMT/DMP systems are eutectic while DMI/DMP is a solid-solution system. The eutectic temperature of DMT/DMI system is 336.7 K and that of DMT/DMP is 271.1 K. Furthermore, a classical solid-liquid phase equilibrium model was used to fit the experimental data of the eutectic systems of DMT/DMI and DMT/ DMP and the theoretical model could describe the eutectic solid-liquid phase diagrams properly.展开更多
基金funded by Programa de Apoyo a Proyectos de Investigacion e Innovacion Tecnologica(PAPIIT)grant IN112314。
文摘The Yelapa-Chimo Metamorphic Complex forms part of the Jalisco Block in western Mexico and exposes a wide range of Early Cretaceous metamorphic rocks;such as paragneiss,orthogneiss,amphibolites,and migmatites.However,the pressure-temperature(P-T)conditions of metamorphism and partial melting remain poorly studied in the region.To elucidate metamorphic P-T conditions,phase equilibrium modelling was applied to two sillimanite-garnet paragneisses,one amphibole-orthogneiss,and one amphibolite.Sillimanite-garnet paragneisses exhibit a lepidoblastic texture with a biotite+sillimanite+kyanite+garnet+quartz+plagioclase+K-feldspar mineral assemblage.Amphibole-orthogneiss and amphibolite display a nematoblastic texture with an amphibole+(1)plagioclase+quartz+(1)titanite assemblage and an amphibole+(2)plagioclase+(2)titanite+ilmenite retrograde mineral assemblage.Pseudosections calculated for the two sillimanite-garnet paragneiss samples show P-T peak conditions at~6-7.5 kbar and~725-740℃.The results for amphibole-orthogneiss and the amphibolite yield P-T peak conditions at~8.5-10 kbar and~690-710℃.The mode models imply that metasedimentary and metaigneous units can produce up to~20 vol%and~10 vol%of melt,respectively.Modelling within a closed system during isobaric heating suggests that melt compositions of metasedimentary and metaigneous units are likely to have direct implications for the petrogenesis of the Puerto Vallarta Batholith.Our new data indicate that the Yelapa-Chimo Metamorphic Complex evolved through a metamorphic gradient between~23-33℃km^-1and the metamorphic rocks formed at depths between~22 km and~30 km with a burial rate of~2.0 km Ma^-1.Finally,the P-T data for both metasedimentary and metaigneous rocks provide new constraints on an accretionary framework,which is responsible for generating metamorphism and partial melting in the YelapaChimo Metamorphic Complex during the Early Cretaceous.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.41972067&41930215)the Fund from the Key Laboratory of Deep-Earth Dynamics of Ministry of Natural Resources(Grant No.J1901-11).
文摘Zircon is a common accessory mineral in various rocks,especially in the crustal ones.It is the best mineral for U-Pb dating.Meanwhile,trace elements and isotopes of the mineral can also provide much information concerning the formation and evolution of rocks.There are a growing number of reports of zircon existing in mantle peridotite.However,it is generally considered that zircon is unlikely crystallized in ultrabasic rocks due to SiO_(2)-unsaturation.In this paper,the SiO_(2) activity and zircon/baddeleyite transition curve at different conditions were calculated through thermodynamic phase equilibrium modeling,to reveal the main factors affecting the SiO_(2) activity and the stability of zircon/baddeleyite in ultrabasic and basic rocks,especially in mantle peridotite.These results provide a thermodynamic basis for interpreting the genesis and significance of zircon in mantle rocks.That is,the SiO_(2) activity is mainly controlled by stable mineral assemblages and temperature-pressure conditions.The orthopyroxene+olivine assemblage in peridotite as an effective buffer restricts the SiO_(2) activity in a relatively high range with a small variation.The upper temperature limit of zircon can reach more than 1500℃ with this mineral assemblage.During the low-temperature serpentinization of peridotite,the replacement of olivine and pyroxene by serpentine can result in a significant decrease of SiO_(2) activity,and baddeleyite can be stabilized at<530℃ and<2.7 GPa.When peridotite is strongly metasomatized by the SiO_(2)-bearing fluid,the addition of SiO_(2) can increase its activity and make zircon stable at low temperatures.The SiO_(2) activity in ultrabasic-basic rocks is not only positively correlated with the SiO_(2) content but also negatively correlated with the Ca and Na contents of rocks.This is because Ca and Na preferentially combine with Si and Al to form Si-rich minerals,such as clinopyroxene and feldspar.This process will consume excessive SiO_(2),decreasing the SiO_(2) activity.This may be the reason why zircon can be found in ultrabasic rocks,while baddeleyite can exist in some basic and alkaline rocks.The thermodynamic modeling can also reasonably explain the mutual transformation between zircon and baddeleyite in ultrabasic-basic rocks.Our results indicate that zircon can exist stably in mantle peridotite in a wide range of temperature-pressure conditions and its formation is related to melt/fluid metasomatism.That is,the presence of zircon in mantle peridotite is an important information carrier of crust-mantle interaction for deep material cycling.
基金financially supported by the National Natural Science Foundation of China (Nos. 41630207, 41572180)the China Geological Survey (No. DD20160022)
文摘The granulitized eclogites from the Luliangshan terrane of the North Qaidam UHP metamorphic belt occur as lenses within pelitic gneisses and orthogneisses. Combined petrologic data and phase equilibrium modeling indicate a multi-stage metamorphic history of the granulitized eclogites:(1) an earlier eclogite facies metamorphism(P>18.5 kbar, T> 830℃) is deduced from omphacite relics in the matrix and rare omphacite inclusions within garnet. The possible assemblage is garnet+omphacite+rutile+ quartz;(2) the early stage of high pressure granulite facies assemblages(garnet+clinopyroxene+ plagioclase+rutile+quartz+liquid) developed in the early decompression process has a P-T regime of 17.5 kbar and 852–858 ℃, constrained by plagioclase and clinopyroxene inclusions in garnet. The late stage of high pressure granulite assemblages(garnet+clinopyroxene+amphibole+plagioclase+rutile+quartz+liquid) records an isothermal decompression process with the pressure successively declining from 17.5 to 14.7 kbar and to 11.3 kbar at 858 ℃;(3) the later medium pressure granulite facies assemblage(garnet+ orthopyroxene+clinopyroxene+amphibole+plagioclase+ilmenite+liquid+quartz) indicates a drop in pressure and rise in temperature at P-T conditions of 7.6–7.7 kbar and 878–883 ℃;(4) retrogressive amphibolite facies stage, which is represented by amphibole+plagioclase kelyphitic rims around garnet, formed under conditions of <5 kbar and <650 ℃. The preservation of medium pressure granulite facies assemblage and the garnet composition feature constrain a following isobaric cooling path during late exhumation. This process suggests a clockwise P-T path and indicates that the granulitized eclogites record a high grade "Barrovian" metamorphic overprint at the middle-lower crust during exhumation. The present data show that the Luliangshan terrane is a "hot" HP-UHP terrane.
基金Project(2007CB714001) supported by the National Basic Research Program of China (973 Program)
文摘In contrast to the traditional interpretation of shear bands in sand as a bifurcation problem in continuum mechanics,shear bands in sand are considered as high-strain phase(plastic phase) of sand and the materials outside the bands are still in low-strain phase(elastic phase),namely,the two phases of sand can coexist under certain condition.As a one-dimensional example,the results show that,for materials with strain-softening behavior,the two-phase solution is a stable branch of solutions,but the method to find two-phase solutions is very different from the one for bifurcation analysis.The theory of multi-phase equilibrium and the slow plastic flow model are applied to predict the formation and patterns of shear bands in sand specimens,discontinuity of deformation gradient and stress across interfaces between shear bands and other regions is considered,the continuity of displacements and traction across interfaces is imposed,and the Maxwell relation is satisfied.The governing equations are deduced.The critical stress for the formation of a shear band,both the stresses and strains inside the band and outside the band,and the inclination angle of the band can all be predicted.The predicted results are consistent with experimental measurements.
文摘Vapor-liquid phase equilibrium data including composition,densities,molar volume and equilibrium constant of isobutanol in supercritical carbon dioxide from 313.2K to 353.2K were measured in a variable-volume visual cell.The properties of critical point were obtained by extrapolation.The results showed that critical temperature,critical pressure and critical compressibility factor of CO2-isobutanol system decreased with the increase of critical CO2 content.The phase equilibrium model was established by Peng-Robinson equation of state and van der Waals-2 mixing regulation,and model parameters were determined by optimization calculation of nonlinear least square method.The correlation between calculated values and the experimental data showed good agreement.
文摘The Isin g model is used to investigate (0001), (10^-10), (10^-11) interfaces, etc. , for the hcp lattice. The system studied here have the nearest-neighbor (NN) and next-nearest-neighbor (NNN) pair interactions. The interface energy, interface phase transition at zero temperature and roughening temperature are used to analyse the properties of these interfaces. As a special case of the hcp crystals, we give the equilibrium shape of the He crystal at T=OK.
基金supported by the National Natural Science Foundation of China(Grant Nos.42162012,42072094)the Key Laboratory of Sanjiang Metallogeny and Resource Exploration and Utilization,Ministry of Natural Resources(Project No.ZRZYBSJSYS2022001).
文摘The Dahongshan Group,situated at the southwestern margin of the Yangtze Block,represents a geological unit characterized by relatively high-grade metamorphism in the region.This paper investigates the garnet-biotite schist from the Laochanghe Formation of the Dahongshan Group,employing an integrated approach that includes petrological analysis,phase equilibrium modeling,and zircon U-Pb dating.The schist is mainly composed of garnet,biotite,plagioclase,quartz,rutile,and ilmenite.Phase equilibrium modeling revealed the peak metamorphic conditions of 8-9 kbar and 635-675°C.By further integrating the prograde metamorphic profile of garnet and geothermobarometric results,a clockwise P-T metamorphic evolution path is constructed,which includes an increase in temperature and pressure during the prograde stage.LA-ICP-MS zircon U-Pb dating and zircon Ti thermometry constrains the post-peak metamorphic age of 831.2±7.2 Ma.Integrated with previously reported results,it is revealed that the southwestern margin of the Yangtze Block experienced a large-scale regional metamorphism during the Neoproterozoic(890-750 Ma),which is related to the collisional orogenic process.This may be associated with the late-stage assembly of the Rodinia supercontinent or with local compression and subduction processes during the breakup of the Rodinia supercontinent.
文摘The binary solid-liquid equilibrium of Dimethyl Terephthalate （DMT）, Dimethyl lsophthalate （DMI） and Dimeth- yl Phthalate （DMP） was investigated by experiment and differential scanning calorimetry （DSC）. The result demonstrated DMT/DMI and DMT/DMP systems are eutectic while DMI/DMP is a solid-solution system. The eutectic temperature of DMT/DMI system is 336.7 K and that of DMT/DMP is 271.1 K. Furthermore, a classical solid-liquid phase equilibrium model was used to fit the experimental data of the eutectic systems of DMT/DMI and DMT/ DMP and the theoretical model could describe the eutectic solid-liquid phase diagrams properly.
