鄂尔多斯盆地东西部奥陶系对比再研究

Stratigraphic Division and Correlation of the Ordovician in the Eastern and the Western Ordos Basin: A Review

鄂尔多斯盆地奥陶系可分为两个地层分区,即中东部地层分区和西部地层分区。两个分区奥陶系的划分和对比,是一个长期未决的问题。本次工作在露头剖面的古生物组合及岩性特征分析的基础上,结合钻井剖面的岩石古生物特征和测井曲线特征,将鄂尔多斯盆地东、西部的奥陶系进行了划分和对比:中东部分区奥陶系划分方案与华北地台的基本一致;中东部及西部的下奥陶统均可划分为冶里组和亮甲山组;西部的三道坎组相当于中东部的马家沟一组,桌子山组相当于马家沟二组和马家沟三组,克里木里组相当于马家沟四组、马家沟五组和马家沟六组,乌拉力克组相当于平凉组下部。

The Ordovician in the Ordos basin is developed in two stratigraphic districts, i. e. , the east - central stratigraphical district and western stratigraphical district. The stratigraphic division and correlation of the Ordovician in the two districts have long been an outstanding problem. Analyses of fossil assemblages and lithology in the outcrop section combined with fossils in rocks and logs of drill holes gave the following conclusions; ① the main characteristics and division of the Ordovician in the east-central Ordos are essentially consistent with those of the North China platform; ② the Lower Ordovician can be divided into the Yeli Formation and Liangjiashan Formation in both the east -central Ordos and western Ordos; ③ the Sandaokan Formation in the western Ordos is equivalent to the Majiagou 1 Formation in the east-central Ordos, the Zhuozis-han Formation is equivalent to the Majiagou 2 and Majiagou 3 Formations, the Kelimuli Formation is equivalent to the Majiagou 4, 5 and 6 formations, and the Wulalike Formation is equivalent to the Pingliang Formation.