新疆塔中南坡奥陶系的地层缺失和沉积相变化

ORDOVICIAN LITHOFACIES AND STRATIGRAPHIC LACUNAE IN THE SOUTHERN PART OF THE CENTRAL TARIM,XINJIANG

按照奥陶系内部6个组沉积的时间片段拟定塔中南坡不同区块存在不同程度的缺失。部分关键层段的牙形石和几丁虫组合特征证明一间房组和恰尔巴克组在塔中部分井区是存在的,但恰尔巴克组的分布范围最狭窄。总体上,塔中南坡隆起区地层缺失较多,古城墟隆起基本完整。据缺失状况和岩相展布,显示塔中南坡的沉积单元具有由东往西迁移的特征,且各时段迁移的距离与速度存在较大差异。

The duration of the stratigraphic hiatus within Ordovician sequences is variable in different parts of the Central Tarim region.Evidence from conodont and chitinozoan assemblages suggests that although complete stratigraphic succession is preserved in the Guchenxu High,the Yijianfang and Qiaerbaq formations are mostly missing in the Southern Slope High.Lithostratigraphic distribution indicates that the sedimentary facies successively migrated westward from Early Ordovician onward at different distance and speed.