中国东部燕山期岩浆活动的几个问题  

A Discussion on the Yanshanian Magmatism in Eastern China

作　　者：张旗[1] 赵太平[1] 王焰[1] 王元龙[1] 

机构地区：[1]中国科学院地质与地球物理研究所,北京100029

出　　处：《岩石矿物学杂志》2001年第3期273-280,292,共9页Acta Petrologica et Mineralogica

基　　金：中国科学院知识创新工程基金资助项目 (KZCX1- 0 7);国家"973"资助项目 (G19990 432 0 6 - 0 5 )

摘　　要：中国东部中酸性燕山期岩浆活动非常发育。文中讨论了中国东部燕山期岩浆岩的分区、岩浆系列、埃达克质岩 (adakite_like)、花岗岩源区、花岗岩形成环境、I型和S型花岗岩的含义等问题。认为目前所使用的花岗岩判别图不能用来讨论花岗岩形成的构造环境 ,按照花岗岩源区深度 ,至少可以分出来自地幔、下地壳和中上地壳的 3个深度层次的花岗岩类 ,强调源区深度对花岗岩性质的制约。认为中国东部燕山期大规模岩浆活动可能与地壳拉张环境下大规模拆沉作用导致的软流圈地幔上涌及其引发的玄武岩底侵作用有关 ,而与古太平洋板块的俯冲作用无关 ,中国东部不属于环太平洋构造 -岩浆带。但拆沉作用发生的时间。Igneous series and distribution of the widespread Yanshanian magmatism, adakite, signification of I_ and S_type granite, and the sources, tectonic settings and heat mechanism of granites are discussed in this paper. It is proposed that the tectonomagmatic discrimination diagrams, such as the diagram by Pearce et al . (1984), should be used with caution in distinguishing tectonic settings of granites. The depth of the source is considered to be the most important factor responsible for controlling the nature of granitoid rocks. Acording to the source depth, the authors have classified the granites into three types, viz., mantle_derived, lower_crust_derived, and middle_upper_crust_derived granites. The Yanshanian magmatism in eastern China resulted probably from underplated basaltic magmas generated from upwelling asthenospheric mantle in a continental crust extensional setting, and had nothing to do with the westward subduction of the Paleo_Pacific (or Izanagi) plate. Therefore, the Yanshanian magmatic rocks in eastern China do not belong to the circum_Pacific tectonic_magmatic belt. The reason, time and mechanism of delamination, however, need further detailed studies.

关 键 词：中国东部 燕山期 岩浆活动 花岗岩 形成环境 源区深度 底侵作用 拆沉作用 

分 类 号：P588.121[天文地球—岩石学]