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
THE Dahongshan Group (in short DG) and its basement Dibadu Formation (in short DF) in the southeastof the Yangtze Plate are one of the oldest geological units in the Yangtze Plate. It is established in thisnote by mea...THE Dahongshan Group (in short DG) and its basement Dibadu Formation (in short DF) in the southeastof the Yangtze Plate are one of the oldest geological units in the Yangtze Plate. It is established in thisnote by means of geochemistry that the system of trench-arc-basin was formed by the subducting at thesouthwestern boundary of the Yangtze Plate in Lower Proterozoic Subera. And the existence of enrichedmantle EMI is argued by the way of trace elements geochemistry. 1 Regional geological setting There is a unit of the typical two-layer structure platform in the southwest of the Yangtze Plate. Themetamorphic basement of this platform is made up of Suberathem Dahongshan Group and SuberathemKunyang Group. Above them, there have covered expansive continental deposits from Mesozoic. The primary rocks of DG are composed of deposited limestone, sandstone and basalts. The basalts represent展开更多
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 Dahongshan Group (in short DG) and its basement Dibadu Formation (in short DF) in the southeastof the Yangtze Plate are one of the oldest geological units in the Yangtze Plate. It is established in thisnote by means of geochemistry that the system of trench-arc-basin was formed by the subducting at thesouthwestern boundary of the Yangtze Plate in Lower Proterozoic Subera. And the existence of enrichedmantle EMI is argued by the way of trace elements geochemistry. 1 Regional geological setting There is a unit of the typical two-layer structure platform in the southwest of the Yangtze Plate. Themetamorphic basement of this platform is made up of Suberathem Dahongshan Group and SuberathemKunyang Group. Above them, there have covered expansive continental deposits from Mesozoic. The primary rocks of DG are composed of deposited limestone, sandstone and basalts. The basalts represent
