新疆东天山石灰窑-沙尔乔克一带奥陶系

Ordovician Stratigraphy Of the East Tianshan in Xinjiang

石灰窑等地发现奥陶纪藻类化石,导致研究区内原确立的岩石地层单位解体并重新厘定。经野外地质调查和区域地层对比,最终将石灰窑-沙尔乔克一带奥陶系厘定为上奥陶统乌列盖组、上奥陶统大柳沟组和上奥陶统庙尔沟组3个岩石地层单位,明确了分布范围。基于锆石U-Pb年龄、地层接触关系及化石证据等,将3个组的地质时代确定为晚奥陶世。完善了该区域地层格架,对正确认识该区构造演化历史,进一步开展东天山一带地层及岩相和古地理研究提供了基础。

The discovery of Ordovician algal fossils in Shihuiyao and other places led to the disintegration and redefini-tion of the originally established lithostratigraphic units in the study area.Through field geological survey and regional stratigraphic correlation,the Ordovician in the lime Shihuiyao-shaerqiaoke area is finally determined as three lithostrati-graphic units:Upper Ordovician Ulegai formation,Upper Ordovician Daliugou formation and Upper Ordovician Miaoer-gou formation,and the distribution range is defined.Based on zircon U-Pb age,stratigraphic contact relationship and fos-sil evidence,the geological age of the three formation is determined as late Ordovician.The improvement of the regional stratigraphic framework provides a basis for a correct understanding of the tectonic evolution history of the region and fur-ther carrying out the study of strata,lithofacies and paleogeography in the East Tianshan area.