Experimental study on dehydration melting of natural biotite-plagioclase gneiss from High Himalayas and implications for Himalayan crust anatexis
Experimental study on dehydration melting of natural biotite-plagioclase gneiss from High Himalayas and implications for Himalayan crust anatexis
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DOI：
10.1007/bf02900441
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发表时间：
2001-05
影响因子：
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通讯作者：
Xiaosong Yang;Zhenmin Jin;H. Ernst;F. Schilling;Wunder Bernd
中科院分区：
文献类型：
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作者：
Xiaosong Yang;Zhenmin Jin;H. Ernst;F. Schilling;Wunder Bernd
本文介绍了在1.0- 1.4GPa、770-1028°C条件下对天然黑云母-斜长石片麻岩进行的脱水熔融实验的结果。实验结果表明：（i）即使熔体量小于5vol%，熔体仍倾向于沿着矿物边界分布，形成“熔体膜”，熔体连通性不仅受熔体拓扑结构控制，还受熔体分数控制;（ii）脱水熔融过程包括亚固相线脱水反应、流体迁移、有汽熔融和无汽熔融等一系列子过程;（iii）实验产生的过铝质花岗岩熔体的成分与高喜马拉雅浅色花岗岩（HHLG）相似，残余相组合为Pl+Qz+ Gat+Bio+Opx±Cpx+Ilm/Rut±Kfs，可与喜马拉雅地区观察到的麻粒岩相媲美。实验证明黑云母-斜长片麻岩是HHLG的源岩之一，脱水熔融是形成HHLG和麻粒岩的重要途径。此外，实验结果为确定喜马拉雅地壳深熔作用的P-T条件提供了约束。
Here 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.