鄂尔多斯盆地姬塬地区三叠系延长组长4＋5物源方向分析

Chang4＋5 Source Direction Analysis of Triassic Yanchang Formation in Jiyuan Region of Ordos Basin

传统认为姬塬地区三叠系延长组受东北物源的控制，砂体均呈北东向展布。但随着勘探程度的提高，研究区西部砂体主带常常变化较快，很难预测砂体主带方向，这就必须对研究区的物源方向重新进行分析判断。从轻重矿物组合类型、岩石地球化学特征、地震前积特征和古地理格局等多方面系统地综合分析，认为姬塬地区三叠系延长组长4＋5物源主要来自东北和西北地区，同时在一定程度上受西部物源的影响。

In the traditional view, controlled by the northeast source area, sand bodies of Triassic Yanchang Formation in Jiyuan region assumed northeast distribution. But with the increased exploration degree, the main sandbody in the west part of the study area often changes rapidly. It is difficult to predict the direction of main sand belts. This must be re-analyzed and judged on the direction of the source in the study area. From comprehensive analysis of the light-and heavy-mineral assemblages, geochemical characteristics, seismic progradation features and the paleogeographic pattern, it is concluded that： Chang4＋5 sources of Triassic Yanchang Formation in Jiyuan region were mainly from the northeast and northwest provenance. At the same time it was impacted by the western source to a certain extent.