吉林省南部晚元古代地层
THE LATE PROTEROZOIC STRATIGRAPHY OF SOUTHERN JILIN
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摘要: 前言吉南晚元古代地层发育良好,与苏皖、山东、蓟县、辽南均属同一构造单元,系地台型沉积。吉南晚元古代地层位于华北地台东北边缘,出露于浑江流域、鸭绿江流域,抚民屯—孤山子一带,以浑江流域出露的层序最全,其时限介于818~570百万年之间。浑江流域青沟子剖面、大阳岔剖面是两条露头良好,层序连续的自然剖面,剖面底界超覆在中元古界老岭群之上,而顶界又被早寒武世产小壳化石含磷页岩所覆盖,构成衔接南北方层型Abstract: The Late Proterozoic is well developed in southern Jilin. It is distributed in the northern corner of the North China platform. In this paper, on the basis of two natural cross sections with good outcrops and a continuous sequence of strata at Qinggouzi and Taiyangcha and in the light of the result of recent regional surveys, the late Proterozoic in the area is divided as follows. Upper boundary: Early Cambrian Meishucun Stage: phosphatic shale Lower boundary:Middle Proterozoic Dalizi Formation The contacts between formations are all conformable. These formations contain an abundance of stromatolites, metazoans and microflora. The Diaoyutai and Nanfen Formations can be correlated with the Jingeryu Formation of the Qingbaikou System of northern China, while the Badaojiang and Qinggouzi Formations can be correlated with the upper Sinian of southern China. The Qiaotou and Wanlong Formations between both possess conditions of bridging northern and southern China, therefore they can be chosen as the third stratotype section of the late Proterozoic of China.