Experimental study on dehydration melting of natural biotite-plagioclase gneiss from High Himalayas and implications for Himalayan crust anatexis  

作　　者：YANG Xiaosong JIN Zhenmin Ernst Huenges Frank R.Schilling Bernd Wunder 

机构地区：[1]Faculty of Earth Sciences,China University of Geosciences,Wuhan 430074,China [2]GeoForschungsZentrum,Potsdam,D-14473,Germany

出　　处：《Chinese Science Bulletin》2001年第10期867-872,共6页

基　　金：This work was sponsored by the State Key Basic Research and Development Program of China (Grant No. G1998040800); GeoForschungsZentrum in Germany for International Cooperation and the Foundation of the Opened Laboratory of Constitution; Interaction and

摘　　要：Here we present the results of dehydration melting, melt morphology and fluid migration based on the dehydration melting experiments on natural bio-tite-plagioclase gneiss performed at the pressure of 1.0-1.4 GPa, and at the temperature of 770-1028℃. Experimental results demonstrate that: (i) most of melt tends to be distributed along mineral boundaries forming 'melt film' even the amount of melt is less than 5 vol%; melt connectivity is controlled not only by melt topology but also by melt fraction; (ii) dehydration melting involves a series of subprocesses including subsoiidus dehydration reaction, fluid migration, vapor-present melting and vapor-absent melting; (iii) experiments produce peraluminous granitic melt whose composition is similar to that of High Himalayan leucogranites (HHLG) and the residual phase assemblage is Pl+Qz+ Gat+Bio+Opx±Cpx+IIm/Rut±Kfs and can be comparable with granulites observed in Himalayas. The experiments provide the evidence that biotite-plagioclase gneiss is one ofHere we present the results of dehydration melting, melt morphology and fluid migration based on the dehydration melting experiments on natural biotite-plagioclase gneiss performed at the pressure of 1.0–1.4 GPa, and at the temperature of 770–1028°C. Experimental results demonstrate that: (i) most of melt tends to be distributed along mineral boundaries forming “melt filmrd even the amount of melt is less than 5 vol%; melt connectivity is controlled not only by melt topology but also by melt fraction; (ii) dehydration melting involves a series of subprocesses including subsolidus dehydration reaction, fluid migration, vapor-present melting and vapor-absent melting; (iii) experiments produce peraluminous granitic melt whose composition is similar to that of High Himalayan leucogranites (HHLG) and the residual phase assemblage is Pl+Qz+ Gat+Bio+Opx±Cpx+Ilm/Rut±Kfs and can be comparable with granulites observed in Himalayas. The experiments provide the evidence that biotite-plagioclase gneiss is one of source rocks of HHLG and dehydration melting is an important way to form HHLG and the granulites. Additionally, experimental results provide constraints on determining the P-T conditions of Himalayan crustal anatexis.

关 键 词：GNEISS dehydration melting melt topology fluid migration LEUCOGRANITE granulite Himalayas. 

分 类 号：P588.3[天文地球—岩石学]