摘要
冀东地区的古老变质岩系是一个出露的大陆地壳断面。根据变质岩系的变质相、亚相的研究和地质温压计计算的结果推定的深度,并结合地球物理测深资料,以及笔者测定和前人的岩石高压下波速实验资料提出了本区大陆地壳结构的岩石学模型。下地壳由麻粒岩相岩石组成,上部为角闪石麻粒岩亚相的中性成分的麻粒岩,下部为辉石麻粒岩亚相的基性成分的麻粒岩构成,底部夹有透镜状蛇纹石化橄榄岩以及紫苏花岗岩。中地壳主要由高角闪岩相的中性-中酸性成分的片麻岩、片岩构成,顶部为低角闪岩相的片麻岩、片岩,广泛发育英云闪长岩和花岗闪长岩岩体,含隙间高温流体相(fluid phase),形成高导-低速层。上地壳主要为绿片岩相(部分低角闪岩相)的板岩、千枚岩、片岩、变粒岩以及花岗岩组成,顶部为沉积盖层。
Precambrian metamorphic complex in East Hebei, China, may be considered to re- present an exposed part of transect of the continental crust. Based on the estimated depth of the metamorphic complex deduced from metamorphic facies and subfacies, geo-thermometry, and geobarometry in combination with geophysical data, previous and our measurements of seismic velocities of rocks, a petrological model for the crustal structure in East Hebei, China, is suggested (Fig. 3). The lower crust consists of granulite facies, the lower and upper parts of the lower crust are composed of Py-granulite of mafic composition and Hb-granulite of intermediate composition, respectively. There are some peridotite bodies and charnockite intrusions in the lower part of the lower crust. The middle crust consists mainly of gneiss and schists of intermediate-acidic composition of high-amphibolite facies. The top of the middle crust is composed of gniess and schists of low-amphibolite facies. Tonalite and granodiorite intrusions with high-temperature pore fluid phase are developed in the middle crust, which corresponds to a high conductivety-low velocity layer. The upper crust is mainly composed of slates, phyllites, schists, granulite of greenschist facies (partly low-amphibolite facies) and granite intrusions, and sedimentary rocks at the top.
出处
《地震地质》
EI
CSCD
北大核心
1991年第4期369-376,共8页
Seismology and Geology
基金
国家地震局地震科学联合基金
关键词
地壳
结构
岩石学模型
变质相
East Hebei, Continental crust structure, Petrological model, Metamorphic facies, Geothermobarometry
