吉林延边安图县海沟地区海沟岩群的建立及其意义

吉林延边安图县海沟地区的海沟岩群系1/5万区域地质调查新建的特殊岩石地层单位(Speciallithostrati-graphicunits),由3个岩组构成:团结岩组为碎屑岩夹大理岩;东方红岩组为一套中酸性火山熔岩及其火山碎屑岩夹凝灰质砂岩;四岔子岩组为一套含铁岩系,主要由黑云变粒岩、斜长角闪岩夹磁铁石英岩组成。三者的接触关系均为断层接触,而且四周为元古代、早古生代的花岗岩所侵吞,属华北板块北缘东段残留的的构造岩片堆积产物,其时代为中元古代。这个岩组的建立,对探讨华北板块北缘东段中元古代地层划分和对比、陆缘裂谷的形成演化与成矿作用的关系以及新元古代Rodinia超大陆的形成等均具有重要的意义。

THE ESTABLISHMENT OF THE HAIGOU COMPLEX IN THE HAIGOU AREA OF ANTU COUNTY, YANBIAN, EASTERN JILIN,AND ITS GEOLOGICAL SIGNIFICANCE

The Haigou Complex, in the Haigou area of Antu County in Yanbian of eastern Jilin Province, was an informal lithostratigraphic unit established by the authors and their colleagues during the regional geological mapping of the Chaoyangtun area. The unit consists of three lithological units: the Tuanjie Formation consisting of clastic rocks and marbles; the Dongfanghong Formation consisting of intermediate to felsic volcanics, volcaniclastics, and tuffaceous sandstones; the iron-rich Sichazi Formation consisting of biotite granulite, plagioclase-amphibolite, and magnetite quartzite. The three formations are in fault contact with each other. They were intruded by Proterozoic and early Paleozoic granites. There is no recognizable stratigraphic sequence within the three formations. They may represent a Middle Proterozoic tectonic slice along the eastern segment of the northern North China Plate. The establishment of the Haigou Complex would be of significance in the following respects: middle Proterozoic lithostratigraphic subdivision and correlation, the formation and evolution of rift-valleys and its relation to mineralization, and the assembly of the Rodinia Supercontinent in the Late Proterozoic.