泥质岩及其变质脱水产物中含水矿物稳定性的实验研究  

Experimental Study on the Stability of Hydrous Minerals in Natural Pelitic System

作　　者：李营[1] 唐红峰[1] 刘丛强[1] 周志华[1] 

机构地区：[1]中国科学院地球化学研究所地球深部物质与流体作用地球化学研究室

出　　处：《高压物理学报》2006年第3期257-264,共8页Chinese Journal of High Pressure Physics

基　　金：中国科学院知识创新工程重要方向项目(KZCX2-SW-124);国家自然科学基金项目(40272038)

摘　　要：俯冲带沉积物（岩）的变质脱水作用对俯冲带流体组成、矿物和同位素组成及岛弧岩浆演化具有深远影响。以天然泥质岩为研究对象，通过高温高压实验，确定了1．5～3．5GPa、746～930℃条件下，俯冲带沉积物中绿泥石、绢云母及其脱水后产物角闪石和黑云母在俯冲带的稳定范围，绘制了高温高压条件下泥质岩体系相图。研究结果表明，在泥质岩体系中，绿泥石是最早发生变质脱水的矿物，在俯冲带50km深度以上全部分解，其分解产物——角闪石可携带流体进入到俯冲带85km处，黑云母则可俯冲至120km或更深的深度，据此可知，在俯冲带深部，沉积物完全脱水的深度范围（≥120km）要大于蚀变洋壳（90～100km）。Metamorphic dehydration of subducted sediments is of importance in understanding the composition of slab-derived fluids, the mineral and isotope composition in subduction zone, which is also important for understanding the evolution of arc magmas. The stability of chlorite,sericite,amphibole and biotite has been identified in natural pelitic system at pressures 1.5～3.5 GPa,and at temperatures 746～930℃ by high pressure experiments on natural pelite. The systematic diagram suggests that with the increasing of pressure and temperature chlorite completely decomposes at lower depth 〈50 km. The run production of this process-amphibole can be subducted to 85 km,and biotite devolatilizes at the depth ～120 km in subduction zone. This leads to the conclusion that subducted sediments can be subducted into more deep depth （≥120 km） than basaltic oceanic crust.

关 键 词：俯冲带 泥质岩 含水矿物 变质脱水作用 

分 类 号：O521.2[理学—高压高温物理] P589.1[理学—物理]