柴达木盆地西北部红三旱地区始新世—渐新世砂岩物源分析

Provenance analysis of Eocene-Oligocene sandstones in the Hongsanhan area,northwestern Qaidam basin,Qinghai,China

柴达木盆地西部红三旱一号三高点上、下干柴沟组砂岩的骨架矿物成分的模式分析显示,始新统—渐新统砂岩的源区主要为再旋回造山带。根据古水流推断物源区主要为阿尔金山。结合上、下干柴沟组砂岩成分模式分析的标准偏差对比和骨架矿物成分平均含量的变化特征,认为渐新世时(上干柴沟组)阿尔金山存在一期隆升事件。

The modal analysis of the sandstone framework minerals in the Upper Ganchaigou and Lower Ganchaigou formations at Height 3 of the Hongsanhan No. 1 area, western Qaidam basin, suggests that the provenance of Eocene-Oligocene sandstones is mainly a recyclic orogenic zone. According to the paleocurrents, it is inferred that the provenance is mainly the Altyn Tagh Mountains. Based on the triangular discrimination diagrams of sandstones showing the standard deviation polygons for the Upper Ganchaigou and Lower Ganchaigou formadons in the Hongsanhan area and variations of the average framework mineral composidons of sandstones, differences between the Upper Ganchaigou and Lower Ganchaigou formations may be observed, which shows that the Altyn Tagh Mountains began to be uplifted in the Oligocene （Upper Ganchaigou Formation）.