赣东北古蛇绿岩带及板块构造基本特征

古蛇绿岩带代表着一个古海洋壳残体,因此近年来日益被人们所重视。研究它对板块构造的研究不仅具有实际意义,而且在理论上和生产实践上同样具有重要作用。本文在前人工作的基础上,进行综合整理分析研究,初步论述赣东北早震旦纪古蛇绿岩带的存在及板块构造的基本特征,有不足之处,望大家指正。一、古蛇绿岩带的基本特征赣东北地区发育一条“赣东北深大断裂带”,向北东延入浙江省境内,向南西至江西省中港坂一带,被白垩纪火山岩覆盖。该断裂带位于“江南隆起”和“上饶坳陷”接壤

BASIC CHARACTERISTICS OF AN ANCIENT OPHIOLITE BELT AND PLATE TECTONICS IN NORTHEASTERN JIANGXI

In this paper several early Sinian geological sections are selected to prove for the first time the existence of an ancient ophiolite belt in northeastern Jiangxi. Evidence is from the rock association,mode of occurrence and mode of emplacement of ultrabasic masses and some petrological characteristics. It is considered that the ultrabasic masses were the products of overthrusting by forceful tectonic action （i. e. cold emplacement） and did not result from mag- matic intrusion. From the base upwards the rock association of the ophiolites is ultrabasic rocks and diabase-intermediate-basic volcanic rocks-glauconite si- liceous rocks-flysch formation. Finally the paper gives a brief account of the basic characteristics of the paleoplate tectonics in northeastern Jiangxi. In early Proterozoic time,the flysch formation at the obducted side of the Yangtze paleoplate in this area was over ten thousand meters in thickness. By early Sinian time,the Yangtze paleoplate was compressed by the subduction of the "Pacific plate",bringing about the inversion of part of geosynclines in the Yangtze paleoplate and the formation of a continental fold mountain system--the Jiangnan ercuate uplift. In Mesozoic time,collision,compression and folding of continental crusts gave rise to a series of mountain systems. This paper proposes the existence of an ancient ophiolite belt and the process of evolution of the paleoplate in the hope of drawing attention from geological,geophysical and geochemical workers concerned.