| 滇西香格里拉阿热岩体岩相学与矿物化学特征及意义 |
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| 引用本文： | 董毅,刘显凡,邓江红,任科法,李春辉,赵甫峰.滇西香格里拉阿热岩体岩相学与矿物化学特征及意义[J].地质学报,2013,87(4):498-514. |
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| 作者姓名： | 董毅 刘显凡 邓江红 任科法 李春辉 赵甫峰 |
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| 作者单位： | 成都理工大学地球科学学院，成都，610059;成都理工大学地球科学学院，成都，610060;成都理工大学地球科学学院，成都，610061;成都理工大学地球科学学院，成都，610062;成都理工大学地球科学学院，成都，610063;成都理工大学地球科学学院，成都，610064 |
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| 基金项目： | 中国地调局地调项目(212011120587)和矿物学岩石学矿床学国家重点（培育）学科建设项目(SZD0407) |
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| 摘 要： | 阿热岩体呈NNE方向展布于义敦岛弧带中甸弧南端，与相邻格咱断裂方向一致。岩体主要发育有角闪闪长玢岩、辉石闪长玢岩、含辉石角闪闪长玢岩及石英闪长玢岩。本文根据岩体内斑晶分布特征，选择角闪闪长玢岩、辉石闪长玢岩及含辉石角闪闪长玢岩及其析离体中的角闪石和单斜辉石进行岩相学及矿物化学研究，其结果显示岩体中角闪石及单斜辉石均分为高Mg#及低Mg#两类，角闪石及辉石均发育与岩浆混合作用相关的不平衡结构，存在同源异相岩浆混合作用，分异结晶作用不明显；成岩岩浆与三叠纪俯冲的甘孜-理塘洋壳板片有关，俯冲过程中板片脱水形成的流体及部分熔融形成的熔体与地幔楔交代是其岩浆形成的重要机制，其岩浆过程主要受构造应力控制，由不富水或局部富水岩浆向富水岩浆演化，具高MgO及SiO2/Al2O3向低MgO及SiO2/Al2O3演化的特点；角闪石温度压力估算结果显示先形成的低Mg#角闪石结晶压力远大于高Mg#角闪石。根据岩浆侵位的构造、压力环境及其动力学背景，我们认为甘孜-理塘洋壳向西俯冲过程中由于中咱地块西侧的羌塘地块于中三叠时期(~230Ma)开始向东挤压碰撞，在此过程中洋壳板片可能发生断离，导致该区背景构造挤压应力在228~219Ma期间先增大后变小。
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| 关 键 词： | 滇西阿热岩体 岩相学 矿物化学 地质温压计 构造背景 |
| 收稿时间： | 6/28/2012 5:06:52 PM |
| 修稿时间： | 11/3/2012 5:09:59 AM |
Petrography Mineral Chemistry and Implications of the A're Porphyry of Shangri La Western Yunnan |
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| DONG Yi,LIU Xianfan,DENG Jianghong,REN Kef,LI Chunhui and ZHAO Fufeng.Petrography Mineral Chemistry and Implications of the A''re Porphyry of Shangri La Western Yunnan[J].Acta Geologica Sinica,2013,87(4):498-514. |
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| Authors: | DONG Yi LIU Xianfan DENG Jianghong REN Kef LI Chunhui and ZHAO Fufeng |
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| Institution: | Chengdu University of Technology,Chengdu University of Technology,Chengdu University of Technology,Chengdu University of Technology,Chengdu University of Technology,Chengdu University of Technology |
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| Abstract: | A're porphyry is located at the north end of the Zhongdian Arc, which is consistent with the direction of the Geza Fault (NNE). It is mainly composed of amphibole diorite porphyry, clinopyroxene diorite porphyry, clinopyroxene amphibole diorite porphyry and qaurtz diorite porphyry. Accroding on the distribution of the phenocrysts in A're porphyry, we study the petrography and mineral chemistry of the amphibole diorite porphyry, clinopyroxene diorite porphyry, clinopyroxene amphibole diorite porphyry and the schlieren. The result display that both of the amphibole and clinopyroxene can be divided into high Mg# and low Mg#, furture with the disequilibrium textures which formed by magma mixing, and crystallization fraction is not obvious; these magmas are connected to the subducting Ganzi-Litang ocean slab of Late Triassic and related to the partial melting of the overly mantle which experienced the fluid and melts from Ganzi-Litang slab, and the magma process are controlled by tectonic stress. These magmas were poor in water or local water-rich, and then they became water-rich, meanwhile the geochemical characteristics changed, such as from high MgO and SiO2/Al2O3 ratio to the low MgO and SiO2/Al2O3. The amphibole geothermobarometry exhibits the pressure of low mg #amphiboles, which formed at early stage, are higher than the high Mg# amphibole. Based on the magma tectonic setting, tectonic stress and dynamic background, we believe that with the westward subduction of the Ganzi-Litang Ocean slab and eastward extrusion of the Qiangtang Block (~230Ma), and the ocean slab may break-off during 228~219Ma, the tectonic stress in the research area increased firstly and subsequently reduced. |
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| Keywords: | A're Porpyphy Petrography Mineral Chemistry Geothermobarometry Tectonic Setting |
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