扬子陆块北缘地壳的钕同位素组成及其构造意义

NEODYMIUM ISOTOPIC COMPOSITIONS OF CONTINENTAL CRUST IN THE NORTHERN MARGIN OF YANGTZE BLOCK AND ITS TECTONIC IMPLICATIONS

本文报道了扬子陆块北缘主要地体的变质岩和沉积岩钕同位素组成。根据这些数据和陈江峰等已发表的皖南变质岩和沉积岩钕同位素数据可以初步获得一扬子陆块东段钕同位素地球化学图。该图表明，在晋宁运动期，扬子陆块的南北陆缘区均为构造岩浆活动带，南大别地体为北缘活动带之一部，佛子岭群是华北陆块南缘的复理石建造，其基底为较年青的火山－沉积建造，构造背景与弧后盆或弧前类似。大别山超高压片麻岩的原岩为具有非常古老（太古宙）物源区的沉积岩。

The Neodymium isotopic compositions of metamorphic and sedimentary rocks from major geological units in the north margin of the Yangtze Block,together with previous data, can be used to make a Nd isotopic plot for the eastern section of the Yangtze Block.This plot shows that both southern and northern continental margins of the Yangtze Block were mobile tectonic-magmatic belts during the Jinning Movement (0.7-1.0Ga).The southern Dabie terrain is part of the northern mobile belt.The Foziling Group is a flysch formation in the southern margin of the North China Block.It has a basement consisting of relatively young volcanicsedimentary formations,and is similar to back-arc or front arc basins in tectonic setting.The protolith of the superhigh pressure metarnorphic gneiss from southern Dabie terrain came from very old (Archean) terrains.