南阿尔金高压-超高温麻粒岩变质作用:大陆地壳超深俯冲与折返过程的记录

董杰; 魏春景; 张建新

doi:10.3799/dqkx.2019.233

Volume 44 Issue 12

Dec. 2019

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Dong Jie, Wei Chunjing, Zhang Jianxin, 2019. Metamorphism of High Pressure-Ultrahigh Temperature (HP-UHT) Granulites from South Altyn Orogen: Records for Ultradeep Subduction and Exhumation of Continental Crust. Earth Science, 44(12): 4004-4008. doi: 10.3799/dqkx.2019.233

Citation:

Dong Jie, Wei Chunjing, Zhang Jianxin, 2019. Metamorphism of High Pressure-Ultrahigh Temperature (HP-UHT) Granulites from South Altyn Orogen: Records for Ultradeep Subduction and Exhumation of Continental Crust. Earth Science, 44(12): 4004-4008. doi: 10.3799/dqkx.2019.233

Citation:

Dong Jie, Wei Chunjing, Zhang Jianxin, 2019. Metamorphism of High Pressure-Ultrahigh Temperature (HP-UHT) Granulites from South Altyn Orogen: Records for Ultradeep Subduction and Exhumation of Continental Crust. Earth Science, 44(12): 4004-4008. doi: 10.3799/dqkx.2019.233

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Metamorphism of High Pressure-Ultrahigh Temperature (HP-UHT) Granulites from South Altyn Orogen: Records for Ultradeep Subduction and Exhumation of Continental Crust

doi: 10.3799/dqkx.2019.233

Dong Jie^{1
,
,},
Wei Chunjing^{1
,
,
,},
Zhang Jianxin²

1.
School of Earth and Space Sciences, Peking University, Beijing 100871, China
2.
Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China

Received Date: 2019-08-19
Publish Date: 2019-12-15

Abstract

Abstract

The South Altyn orogen is a typical continental ultrahigh-pressure (UHP) belt which is claimed to host the deepest subducted crustal rocks. HP-UHT granulites occurred in the belt are of significance for understanding the ultradeep subduction and exhumation of continental crust. This paper presents the results of petrography,mineral chemistry,phase equilibria modelling and zircon U-Pb dating for felsic and mafic granulites from Bashiwake area. Mafic granulites have mainly recorded the exhumation process of ultradeep continental crust,with metamorphic evolution from HP eclogite facies to HP-UHT granulite facies,further to low-pressure (LP)-UHT granulite facies conditions and the subsequent isobaric cooling. In addition to the similar exhumation to that of mafic granulites,felsic granulites have also preserved the early prograde history from amphibolite facies to UHP eclogite facies conditions. Combing previous studies,the peak conditions of UHP eclogite facies is estimated to be > 7-9 GPa and > 1 000℃,covering the stishovite-stability field. Zircon age dating suggests that both felsic and mafic granulites have similar protolith ages of~900 Ma and metamorphic ages of~500 Ma. Metamorphic and dating studies indicate that the South Altyn continental crust was subducted to ultradeep depths of 200-300 km during the Early Paleozoic and exhumed to the bottom of a thicken crust where HP-UHT metamorphism occurred. Then the crust was uplifted rapidly to the shallow crustal level and experienced LP-UHT metamorphism followed by subsequent isobaric cooling.
- HP-UHT metamorphism,
- felsic granulite,
- mafic granulite,
- continental ultradeep subduction,
- South Altyn orogen,
- petrology

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References(13)

References

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