井冈山逆冲推覆构造基本特征及找矿意义

CHARACTERISTICS OF THE THRUST NAPPE STRUCTRUE IN JINGGANG MOUNTAINS AND ITS MEANING FOR ORE PROSPECTING

井冈山逆冲推覆构造位于华南板块北缘,由一系列规模不等,方向基本一致,倾向南东的叠瓦逆冲推覆断层组成。卷入地层有寒武—震旦系、泥盆系—三叠系及侏罗系和白垩系,空间上具双冲型推覆特征,推覆方向早期由南东向北西,晚期由东向西。据各推覆体的叠置关系及40Ar/39Ar同位素测年结果(184.16Ma),认为该推覆构造主要活动于燕山期。该推覆构造的发现,可能反映出该区中生代存在一定规模的陆内造山,是本区中生代陆内变形的主要方式;同时也为本区寻找隐伏煤矿提供了有力的地质依据,为寻找与构造蚀变岩(推覆面附近)有关的贵多金属矿产指明了方向。

As carring out the regional geological survey at the scale of 1∶50 000 in Jinggang Mountains the authors found the nappe structure. The nappe structure is mainly composed of a series of the NNE NE thrust fault zones and the thrust sheets. The strata of the Sinian, Cambrian, Ordovician, Devonian, Carboniferous, Triassic, Jurassic and Cretaceous are all involved in the thrust nappe system. The nappe structure is double thrust structures that are formed as a result of the sedimentary covering or basement strata partly migrating from southeast to northwest early and from east to west later. The formation of the nappe structure in the studied area is involved mainly in the two epochs: early Yanshanian epoch and later Yanshanian epoch early Himalayan epoch. The mineral deposits and coal fields are extensively controlled by the nappe structure in the area, especially the buried coal fields.