鄂尔多斯盆地侏罗纪—白垩纪原始面貌与古地理演化

Original features and palaeogeographic evolution during the Jurassic-Cretaceous in Ordos Basin

鄂尔多斯盆地位于华北地台西部。在详细分析地层接触关系、构造界面特征、地层发育特征和连续性、盆地沉积与周边构造的关系、物源区性质、沉积体系配置与相分布、古水流样式等各种要素的基础上,重建了鄂尔多斯盆地侏罗纪至白垩纪的原始面貌,并将其演化划分为4个阶段。其中,第一阶段(早侏罗世至中侏罗世早期)和第二阶段(中侏罗世Bathonian—Callovian期)沉积盆地的范围和沉积体系的配置关系大体类似,两者最为重要的区别是前者有聚煤作用发生,后者没有煤层发育,其原因是古气候变化造成的;第三阶段(晚侏罗世)盆地收缩至桌子山—石沟驿—六盘山一线东侧;第四阶段(早白垩世)盆地的范围有所扩大,但东界可能被限制于现今的吕梁山以西。

The Ordos Basin is located in the western part of the North China Platform. Based on the detailed analyses of different elements, such as the contact characteristics of the strata, characteristics of structural boundaries, stratigraphic development characteristics and continuity, relationships between depositional basin and its neighboring tectonic units, properties of the provenance area, sedimentary systems and facies distribution, palaeocurrent patterns, etc., the original features from the Jurassic to the Cretaceous in the Ordos Basin are reconstructed. The evolution of the basin can be divided into four stages. During the first stage （from the Early Jurassic to the early Middle Jurassic） and the second stage （the Batho- nian-Callovian of the Middle Jurassic） , the basin extent and the sedimentary system distribution were similar. The most important difference between the two stages is that coal accumulation occurred in the first stage while it did not exist in the latter, which is attributed to the palaeoclimate change. The basin shrank and was present only to the east of the Zhuozishan-Shigouyi-Liupanshan Mountains during the third stage （Late Jurassic） of the basin evolution. In the forth stage of the basin evolution （Early Cretaceous）, the basin expanded slightly, and its eastern boundary maybe extend to the west of the present LOliangshan Mountain.