| Geological Implications for the Deep-Derived Mafic Enclaves from Cenozoic Shoshonitic Rocks in Jianchuan-Dali Area,West Yunnan |
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| 作者姓名： | 王建 李建平 王江海 马志红 |
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| 作者单位： | Guangzhou Institute of Geochemistry Chinese Academy of Sciences，Guangzhou Institute of Geochemistry Chinese Academy of Sciences，Guangzhou Institute of Geochemistry Chinese Academy of Sciences，The Institute of Earth Sciences Jilin University Guangzhou 510640，China，Guangzhou 510640，China，Guangzhou 510640，China，Changchun 130026，China |
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| 基金项目： | ThisresearchwasfinanciallysupportedbytheStateKeyDevelopmentProgrammingProjectonFundamentalResearches (GrantNo .G19980 40 80 0 )andConstitution ,StructureandEvolutionoftheTectonicSystemofSouthChinaSeaandNeighbouringAreas (GrantNo .
KZCX2 - SW- 117) . |
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| 摘 要： | 1ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅＡｉｌａｏｓｈａｎ ＪｉｎｓｈａｊｉａｎｇＣｅｎｏｚｏｉｃａｌｋａｌｉ ｒｉｃｈｐｏｔａｓｓｉｃｍａｇｍａｔｉｃｂｅｌｔｅｘｔｅｎｄｓｏｖｅｒａｄｉｓｔａｎｃｅｏｆ370 0ｋｍｉｎｔｈｅＮＷ ＮＷＷｄｉｒｅｃｔｉｏｎ (ＺｈａｎｇＹｕｑｕａｎａｎｄＸｉｅＹｉｎｇｗｅｎ ,1 997) .Ｓｔｕｄｉｅｓｏｆｐｅｔｒｏｌｏｇｙａｎｄｇｅｏｃｈｅｍｉｓｔｒｙｉｎｄｉｃａｔｅｔｈａｔｔｈｅｉｎｔｅｒｍｅｄｉａｔｅｔｏｉｎｔｅｒｍｅｄｉａｔｅ ａｃｉｄａｌｋａｌｉ ｒｉｃｈｐｏｒｐｈｙｒｙｇｒ…
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| 关 键 词： | shoshonitic rock 矿物地球化学特征 变质作用 新生代 地质学特征 云南 铁镁质岩 变质岩 |
Geological implications for the deep-derived mafic enclaves from Cenozoic shoshonitic rocks in Jianchuan-Dali area,west Yunnan |
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| Wang?Jian,Li?Jianping,Wang?Jianghai,Ma?Zhihong.Geological Implications for the Deep-Derived Mafic Enclaves from Cenozoic Shoshonitic Rocks in Jianchuan-Dali Area,West Yunnan[J].Chinese Journal of Geochemistry,2003,22(1):58-73. |
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| Authors: | Wang Jian Li Jianping Wang Jianghai Ma Zhihong |
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| Institution: | (1) Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 510640 Guangzhou, China;(2) The Institute of Earth Sciences, Jilin University, 130026 Changchun, China |
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| Abstract: | There exist intermediate to intermediate-acid shoshonitic rocks dated at 26. 3–36.7 Ma in the Early Tertiary extensional basins
along the NE flank of the Dali-Jianchuan section of the Honghe-Ailaoshan left-lateral strike-slip ductile shear zone, where
some high- and medium-high grade metamorphosed mafic enclaves have been found. According to theP-T conditions and mineral assemblage characteristics, the enclaves are grouped into three types: type-I, garnet diopsidite,
formed at lower crust or in the transitional section between the mantle and the crust with the metamorphic conditionP= (10.47–11.51) × 108 Pa andT =771-932°C; type-II, garnet- and diopside-bearing amphibolite, formed at the depth of middle to lower crust with the metamorphic
condition:P = (6–10 ) × 108 Pa andT = 780–830°C; type-III, metamorphosed gabbro, formed at relatively higher levels than the above 2 types with lower metamorphic
condition. Type-I and type-II enclaves had experienced a decompressional retrograde metamorphism caused by tectonic elevation
associated with the metasomatism of SiO2, Na2O-rich fluid phase with the new equilibrated temperature atT = 761–778°C. Geochemical evidence indicates that both deep-derived mafic enclaves and host rocks have similar EMII properties, which are related to the involvement of subducted materials. The sustaining subduction, compression and strike-slip
ductile shearing between the India plate and the Yangtze craton are the main constraints on the subcontinental mantle properties,
interaction between crust and mantle, and the formation and evolution of alkali-rich magma.
This research was financially supported by the State Key Development Programming Project on Fundamental Researches (Grant
No. G1998040800) and Constitution, Structure and Evolution of the Tectonic System of South China Sea and Neighbouring Areas
(Grant No. KZCX2-SW-117 ). |
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| Keywords: | shoshonitic rock deep-derived enclave mineralogical geochemistry metamorphism margin of convergent plate western Yunnan |
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