秦巴地区主要地质—构造特征梗概

根据活动论和时空观,从8个方面总结了秦巴地区主要地质-构造特征。介绍了3大综合地层区的概貌,划分太古宇至元古代的地层类型及形成环境。从沉积盆地性质、基底构造格局等方面分析,指出中秦岭构造亚带为南、北板块拚接带的特定构造单元。根据宏观地质及地球化学特征,将本区火山岩的形成归纳为8种构造环境。概括了中酸性及碱性、偏碱性侵入岩类的时空分布和地球化学成分及成因类型等特点。从复杂的断裂系统、多期的叠加变形、多期构造-热事件和地壳极度缩短四方面,说明秦岭-大别山构造带是巨形强应变带。概述了秦巴构造演化8个阶段的主要点及基本构造格局。

A BROAD OUTLINE FOR MAIN CHARACTERISTICS OF GEOLOGICAL STRUCTURE IN QINLING-DABASHAN AREA

The main characteristics of geological structure in Qinling--Dabashan area have been summarized in eight aspects according to mobilism and a new space-time concept, and the outline of three comprehensive stratigraphic are-as (the southern area of the North China, the Qinling-Songpan area and the northern Yangtz area) has also been introduced. The stratigraphic type and its forming environment from Archean era to proterozic ear had been divided as well. It is thought that the middle Qinling structural subzone is a specific tectonic unit between the south and north plates based on analysis for features of the sedimentary basin and the structural framework of its basement. The generation of volcanic rocks in the studied region comes from eight structural environments on the basis of macro-geology and geochemical feature. Space-time distribution, geochemical composition and genetic type of the mid-acid and alkali-partial alikli intrusive rocks has been summarized. It is evident that Qinling-Dabashan structural zone is a megastrain zone on account of the complex fracture system, polysuperimposed deformation, multi-periodic tectono-heat events and intense shortening of earth crust. Besides, the main aspects of eight stages of structural evolution and fundamental structural framework within Qinling-Dabashan area have been outlined.