甘肃南梁-华池地区三叠系延长组长三段储层物源探讨

A DISCUSSION ON SOURCE DIRECTION FROM THE CHANG 3 RESERVOIR,YANCHANG FORMATION IN THE NANLIANG-HUACHI AREA OF GANSU

利用稀土元素和微量元素,分析鄂尔多斯盆地南部南梁—华池地区上三叠统延长组长三段储层母岩类型和物源方向,研究表明盆地南部南梁—华池地区延长组砂岩和泥岩的稀土元素地球化学特征、REE分配模式及微量元素蜘蛛图解相同,与盆地东北缘太古代、元古代变质岩相似,但不相同;与盆地西南缘的水河地区延长组相似且不同,说明研究区与盆地东北缘和西南缘均有较好的亲缘关系。结合轻、重矿物组合和盆地周缘古陆岩矿特征,证实了研究区物源为两个主物源的混合区。

Rare earth elements （REE） and trace elements were used to analyse source rock and source direction of the Bed 3 of Upper Triassic Yanchang Formation in the Ordos Basin. Research shows that the sandstone and mudstone of the Chang 3 in the south of Ordos Basin have same geochemical characteristics, the REE distribution, and trace elements spider diagrams. The geochemical characteristics, the REE distribution, and trace elements spider diagram of sandstone and mudstone in the Bed 3 are similar with the Archean and Proterozoic metamorphic rocks from the northeast basin, but are not identical. The geochemical characteristics, the REE distribution, and trace elements spider diagram of sandstone and mudstone in the Bed 3 are similar with the Yanchang Formation of the Ruishuihe area of south-west basin. It is concluded that the Nanliang-Huachi area is close to the northeast and southwest of the basin. Based on the light and mineral, the petrography of the ancient land, the source direction are the mixing of two main sorces.