鄂尔多斯盆地上古生界砂岩岩石学特征及岩性差异

Petrological characteristics and lithological differences of Upper Paleozoic sandstone of Ordos Basin

康东雅 向芳 邹佐元 张萌

成都理工大学沉积地质研究院，四川 成都 610059

Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, China

文中利用岩石薄片、扫描电镜等方法，详细分析了鄂尔多斯盆地东南部宜川￣富县地区上古生界砂岩岩石学特征及岩性差异。研究结果表明：宜川地区本溪组—石千峰组的岩石类型主要为石英砂岩、岩屑砂岩、岩屑长石砂岩；富县地区与宜川地区基本相同，本溪组—太原组的岩石类型主要为石英砂岩，从山西组开始长石体积分数明显增加，出现岩屑长石砂岩和长石岩屑砂岩。由于构造运动、沉积相演化和物源变化的影响，造成沉积环境和物源区发生变化，本溪组—太原组与山西组—石千峰组砂岩的长石体积分数、岩屑成分、分选性和磨圆度等都不相同，从而导致研究区在不同地区和层位存在岩性差异。

In order to discuss the difference of petrology characteristics of the Upper Paleozoic Benxi Formation to the Shiqianfeng Formation in the Yichuan and Fuxian areas of the southeastern Ordos Basin, comprehensive discussion is made based on thin section identification and observation of SEM(scanning electron microscope), etc. The results suggest that sandstones changes from quartz sandstone to litharenite sandstone then to lithic feldspar sandstone in Yichuan area. The similar but not same phenomena can be observed in Fuxian area: quartz sandstone appeares in Taiyan and Benxi Formations, then feldspar content of sandstone significantly increases in Shanxi Formation and lithic feldspathic sandstone and feldspathic lithic sandstone becomes the dominant ingredients. Due to the influence of tectonic evolution, sedimentary facies evolution and provenance evolution, the sedimentary environment and provenance area of the sea and land changed. The feldspar volume fraction, cuttings composition, sandstone fraction and roundness of the Benxi Formation-Taiyuan Formation and the Shanxi Formation-Shiqianfeng Formation sandstone in the study area selectability are different, resulting in lithological differences in different regions and horizons.

10.6056/dkyqt201903006