| 东准噶尔卡拉麦里黄羊山花岗岩岩石成因探讨 |
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| 关键词:crust-mantle hybrid genesis A type granite diorite microgranular enclave Huangyangshan intrusion Kalamaili East Junggar |
| 基金项目:新疆青河、奇台县红柳沟-苏吉泉一带1∶5万区域地质矿产调查(编号：QD200508) |
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| A Tentative Discussion on the Genesis of Huangyangshan Granite Body in Kalamaili Orogen, East Junggar |
| The Huangyangshan pluton is a typical post-collision pluton in Kalamaili orogen of East Junggar, with many dioritic microgranular enclaves distributed in it. It is characterized by high Si (72.21%~77.36%), low Al (9.00%~12.93%), poor Ca and Mg (CaO 0.20%~1.21%, MgO 0.03%~0.44%), rich alkali (Na2O+K2O 7.43%~ 9.02%), high extent of differentiation (SI=0.28~3.47, DI=76.45~95.99), strong enrichment of LILE and HFSE (Zr+Nb+Ce+Y=260.01μg/g~797.83μg/g), and relatively high Ga content (10000×Ga/Al=3.95~5.69), indicating an A type granite. The lithologic and petrologic characteristics (such as the fine-grained cold-quenching ring of the enclave, the reverse vein, the complex enclaves, the consistency of plagioclase phenocrysts from both host rocks and enclaves in crystal form, composition and optic character), the petrogeochemical data (Y/Nb=2.77~6.82, La/Nb=0.91~4.33, Ba/Nb=0.13~37.86), the Sr and Nd isotope data (most ISr range from 0.7031 to 0.7041, εNd(t)=5.2~7.1) and the LA-ICP-MS zircon U-Pb dating (the age of the host rock is 311±12 Ma, and that of the enclaves is 300±6 Ma) all suggest that the Huangyangshan pluton is of the crust-mantle hybrid genesis. From Late Carboniferous to Permian, Junggar region entered into the post-collision tectonic evolution stage, during which the early subduction slabs were ruptured and separated, the asthenosphere was decompressed and melted, the basalt magma experienced underplating due to the underplating of the basaltic magma, the low crust was melted by the high temperature and formed acid crust-magma, and the mixing between the basic magma from the mantle and the acid magma from the crust took place and formed the Huangyangshan magma-mixed pluton. The dioritic micro-granular enclaves thus serve as the recorder of the crust-mantle magmatic mixing process. |
| YANG Gao-xue,LI Yong-jun,WU Hong-en,SI Guo-hui,ZHANG Yong-zhi,JIN Zhao.2010.A Tentative Discussion on the Genesis of Huangyangshan Granite Body in Kalamaili Orogen, East Junggar[J].Acta Geoscientica Sinica,31(2):170-182. |
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