摘要:
研究区位于喀喇昆仑山北坡的天神达坂—克什尔村—甜水海一带。该区属地质空白区,以往仅在远离本区的西部米计干沟和叶尔羌河黑黑孜地段,依据零星资料确定有寒武—奥陶系。前者岩性为碳酸盐岩、变质碎屑岩（未见顶底）,依岩性可分四个亚群,在中、上部的浅变质岩中发现Heliolites和海百合茎化石,故将地层时代定为寒武—奥陶纪,并命名为米计干群（（?）—0）mj;后者岩性为碎屑岩夹碳酸盐岩,产三叶虫和腕足类化石,时
Abstract:
The northern slope of the Karakorum Mountains is a geological blank area. When the authors carried out a regional geological survey on a scale of 1: 1,000,000 in 1982--1983, the Early and Middle Ordovician strata as well as a large amount of fossils of trilobites, cephalopods, brachiopods, bryozoans, crinoid stems, etc. were first found in Tianshendaban, Dongguashan, Keshir Village and Tianshuihai of the area. The sequence of the strata is relatively complete and overlie unconformably the stromatolite-bearing Tianshuihai Group of the Changcheng System. So the Lower Ordovician is named the Dongguashan Formation, but the Middle Ordovician continues to be called the Nakeshiqijiang Group of the western neighbouring area. Their biota and lith- ology possess the characteristics of the South China type. The discovery of the fossils represented by Szechuanella in the area and the establishment of the section of the Early and Middle Ordovician strata have provided evidence for studying the assignment of the biostratigraphic subregion on the northern slope of the Karakorum Mountains. More signifi- cantly, it has been confirmed that the strata the the area were deposits of the South China platform-type during the early Paleozoic, so the area should be- long to the western extension of the Jiangtang massif. Thus the evidence for the study of the old plates has been provided.
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