Metamorphic Evolution of the Bashiwake Garnet Peridotite from the South Altyn Tagh
详细信息
- 责任者：Li Yunshuai (China University of Geosciences ; Beijing 100083 ; China) ; Zhang Jianxin
- 刊名：Acta Petrologica Sinica
- 出版年：2013
- 卷期：29(6)
- 关键词：变橄榄岩 ; metaperidotite ; 超高压变质作用 ; ultrahigh pressure metamorphism ; 阿尔金山 ; Altun Mountains
- 页码：p.2073-2092
- 图表：illus., 8 tables, 102 refs.
- 分类号：0802
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
Garnet peridotite from the Bashiwake area in the South Altyn Taghoccurs as slices or lenseswithin HP mafic granulite and garnet-bearing felsic gneiss.0n the basis of textural relationships,mineralogical data and temperature and pressure estimates, three stages of the metamorphic evolution have been identified,including peak metamorphic stage ( M1) ,decompression retrograde stage ( M2) and late amphibolite-greenschist facies retrograde stage ( M3) . Stage I isdefined by the assemblage garnet + olivine + orthopyroxene + clinopyroxene,which formed at 891～1054℃ and 17.2 ～24. 7kbar. Stage II is an initial decompression stage, characterized by the formation of kelyphitic rims of orthopyroxene + clinopyroxene + aluminous spinel around garnet,yielding 711～796℃ at 10kbar. Stage III is represented by the formation of amphibole + serpentine + phlogopite + chlorite + magnetite ± talc. The P-T evolution of garnet peridotite is similar to that of the associated high pressure felsic granulite and mafic granulite. Combining with mineralogical and geochemical characteristics,we speculated that the protolith of garnet peridotite was mantle-derived mafic-ultramafic complex emplaced in the crust,whichwas subducted together with felsic crust material in the Early Paleozoic,and they shared the subsequent metamorphic and geodynamic evolution.
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