首页|期刊导航|中国地球化学学报(英文版)|Geological Implications for the Deep-Derived Mafic Enclaves from Cenozoic Shoshonitic Rocks in Jianchuan-Dali Area, West Yunnan
中国地球化学学报(英文版)2003，Vol.22Issue(1)：58-73,16.
Geological Implications for the Deep-Derived Mafic Enclaves from Cenozoic Shoshonitic Rocks in Jianchuan-Dali Area, West Yunnan
Geological Implications for the Deep-Derived Mafic Enclaves from Cenozoic Shoshonitic Rocks in Jianchuan-Dali Area, West Yunnan
摘要
Abstract
There exist intermediate to intermediate-acid shoshonitic rocks dated at 26.3 - 36.7Ma in the Early Tertiary extensional basins along the NE flank of the Dali-Jianchuan section ofthe Honghe-Ailaoshan left-lateral strike-slip ductile shear zone, where some high- and medium-high grade metamorphosed mafic enclaves have been found. According to the P-T conditions andmineral assemblage characteristics, the enclaves are grouped into three types: type- Ⅰ , garnetdiopsidite, formed at lower crust or in the transitional section between the mantle and the crustwith the metamorphic condition P = ( 10.47 - 11.51 ) × 108 Pa and T = 771 - 932℃; type- Ⅱ,garnet- and diopside-bearing amphibolite, formed at the depth of middle to lower crust with themetamorphic condition: P ＝ (6 - 10) × 108 Pa and T = 780 - 830℃; type- Ⅲ, metamorphosedgabbro, formed at relatively higher levels than the above 2 types with lower metamorphic condi-tion. Type- Ⅰ and type-Ⅱ enclaves had experienced a decompressional retrograde metamorphismcaused by tectonic elevation associated with the metasomatism of SiO2, Na2O-rich fluid phasewith the new equilibrated temperature at T = 761 -778℃. Geochemical evidence indicates thatboth deep-derived mafic enclaves and host rocks have similar EMⅡ properties, which are relatedto 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 onthe subcontinental mantle properties, interaction between crust and mantle, and the formationand evolution of alkali-rich magma.关键词
shoshonitic rock/deep-derived enclave/mineralogical geochemistry/meta-morphism/margin of convergent plate/western YunnanKey words
shoshonitic rock/deep-derived enclave/mineralogical geochemistry/meta-morphism/margin of convergent plate/western Yunnan分类
天文与地球科学引用本文复制引用
王建,李建平,王江海,马志红..Geological Implications for the Deep-Derived Mafic Enclaves from Cenozoic Shoshonitic Rocks in Jianchuan-Dali Area, West Yunnan[J].中国地球化学学报(英文版),2003,22(1):58-73,16.基金项目
This research was financially supported by the State Key Development Programming Project on Fundamental Researches (GrantNo. G1998040800) and Constitution, Structure and Evolution of the Tectonic System of South China Sea and Neighbouring Areas( Grant No. （GrantNo. G1998040800）
