受孕地幔的熔融模型在火山岛弧成岩作用中的应用  

TRACE ELEMENT MODELS FOR MANTLE MELTING∶APPLICATION TO VOLCANIC ARC PETROGENESIS

作　　者：袁建平[1] 王仁民[1] 倪志耀[1] 

机构地区：[1]北京大学地质学系,北京100871

出　　处：《地质科技情报》2000年第4期15-24,共10页Geological Science and Technology Information

基　　金：国家自然科学基金资助项目!(49872 0 72 )

摘　　要：结合现代火山岛弧资料的模拟 ,受孕地幔熔融模型的应用成果可概括为以下几点 :与活动陆缘之弧后盆地伴生的洋内弧主要派生自亏损的受孕的大洋中脊玄武岩地幔 (fertile MORB mantle,简称 F MM) ,它在早期熔融事件中已丢失了 3%的熔体 ;亏损发生在尖晶石二辉橄榄岩相中 ,它支持把它与弧后盆地熔融事件相联系的模型 ;与弧后盆地不伴生的大洋岛弧主要派生自FMM,不过富集岩浆源在局部可能起重要作用 ;内陆弧一般派生自富集地幔 ,可能是因为有陆下岩石圈混入 ;在薄层地壳上的洋内弧中 ,熔融程度可能很高 (约 2 5 %～ 30 % ) ,而在岩石圈较厚的地区熔融量则减至 15 %或更少 ;挥发分加入到地幔中诱发的熔融约占 10 % ,余者则是由减压作用所引起的。The application of the trace element models for fertile mantle melting has achieved some results based on the modelling of the data from present volcanic arcs∶Intra oceanic arcs with associated active backarc basins are derived principally from fertile MORB that has lost up to about 3% melt in a previous melting event, which takes place in spinel lherzolite facies. This supports models that relate it to backarc basin melting events. While oceanic arcs with no associated backarc basins are obtained principally from fertile MORB mantle,though enriched sources can be important locally. Intra continent arcs are commonly derived from enriched mantle,probably because of the involvement of sub continent lithosphere. Where degrees of melting are probaly high (in the order of 25%—30%) on thin crust,decreasing to 15% or less in areas of thicker lithosphere. Some 10% melting can be explained by volatile addition to the mantle,and the remainder by decompression.

关 键 词：上俯冲带 分配系数 岩浆 受孕幔 熔融模型 成岩作用 火山岛弧 

分 类 号：P588.1[天文地球—岩石学]