关键词: 冀东, 陆壳结构, 岩石学模型, 变质相, 地质温压计

Abstract: 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.

Key words: East Hebei, Continental crust structure, Petrological model, Metamorphic facies, Geothermobarometry