吉南夹皮沟金矿带鞍山群的解体及主要地质事件序列的建立

位于华北地台最北缘的夹皮沟金矿带太古代鞍山群主要由两类双峰式灰色片麻岩组成,其原岩均为ＴＴＧ类古侵入体夹拉斑玄武岩质暗色包体,岩石化学上与国外许多太古代高变地体中的灰色片麻岩相似,因而不能作为地层来对待。原“鞍山群”可重新划分为白山镇片麻岩、夹皮沟片麻岩和北西向糜棱岩带三大岩石单元,两类灰色片麻岩之间有一些相似处,但也有许多重要差别,可能代表了不同的构造地体。就现有同位素年代数据和野外产状建立了本区主要地质事件的序列。上述岩石单元的划分及主要地质事件序列的建立对本区构造属性的确定及地壳演化的研究有重要的意义。

Disintegration of the Archaean "Anshan Group" and establishment of major geological event succession in Jiapigougou gold metallogenic belt, S. Jilin

It is confirmed that the Archaean "Anshan Group" in the Jiapigou gold metallogenic belt situated in the northernmost margin of N. China Platform is mainly composed of two different-typed bimodal grey gneisses. The protoliths of the gneisses are all ancient TTG intrusive bodies with tholeiitic melanic enclaves. Petrochemically, the gneisses are very similar to the grey gneisses in many Archaean high grade terrains of other countries. The authors disintegrate the "Anshan Group" strata and divide the Archaean rocks into three major unites: Baishanzhen gneiss, Jiapigou gneiss and NW mylonite zone.The respective major geological features of the three rock unites have been described briefly and we recognize that it has a few similarities but also a lot of obvious differences between the two types of gneisses which may belong to two different tectonic terrains. The major geological events succession of this area has been estalished based on the existing isotopic age data and field observations. The division of Archaean rock unites and establishment of geological evolutional succession mentioned above have important significance for the tectonic attributive confirmation and crust evolutional studies in this area.