陶湾群层序及时代研究

陶湾群分布于洛南—栾川一带,分三个自然段出露。本文描述了各地段陶湾群代表性剖面,论述了层序划分和区域对比。文中依据地层接触关系、古生物资料以及同位素地质年龄,确定陶湾群的时代为奥陶纪。

THE SEQUENCES AND THE AGE OF THE TAOWAN GROUP

The Taowan Group is situated in the Luonan-Luanchuan transitional belt between the southern margin of the Northern China Platform and the Northern Qinling. It faces the Kuanping Group on the south and is separated by the Tieluzi-Luanchuan Fault. Its north boundary is discordant on the different positions from the Jixian system to the Cambrian system and under the Shihezi formation of the lower Permian series. Spatially, it is divided into three sections by two cainozoic basins,the Lushi Basin and the Luanan Basin. All of them have the same stratigraphical characteristics and sequence. Its lower part is composed of calcareous conglomerates and carbonaceous phyllites intercatated with dolomites and limestones; the middle part is characterized by sandy pelitic carbonate rocks, and the upper part, being absent in the Luanchuan district, consists of silty phyllites intercalated with carbonaceous. The age of the Taowan group is thought of as the Ordovicaan Period according to the data of the stra-tigraphical contact relation, the isotope age and the biology. The three conglomerate suites were recognized in the trasitional belt.They were "the Taowan conglomerate", "the Sandaozhuang conglomerate" and "the Wangyu conglomerate" Based upon the newest results of their research and investigation the writers divided it into two suites in the belt: the Precambrian Luoquan conglomerate and the conglomerates of the Taowan Group.