松辽盆地南部油页岩微量元素特征及其成矿期古环境恢复

油页岩成矿期的古环境控制着油页岩有机质类型与丰度,而油页岩的有机质类型和丰度对于研究油页岩成因及富集规律具有重要的意义.松辽盆地南部含油页岩层段总体为深湖-半深湖相稳定沉积,微量元素特征对古环境的变化敏感,可利用油页岩微量元素含量的测试及其比值分析的方法恢复油页岩成矿期的古环境.通过对松辽盆地南部油页岩样品中20余种微量元素含量的测试及其比值的分析,恢复了青山口组与嫩江组油页岩成矿期的古环境.研究结果表明,油页岩成矿期的古气候为温暖湿润-半湿润半干热的气候,水介质为微咸水—半咸水的还原环境.青山口期相对嫩江期气候和盐度变化较稳定,气候略为干热,盐度也略高.

CHARACTERISTICS OF TRACE ELEMENTS IN OIL SHALE AND PALEOENVIRONMENT RECOVERY IN THE METALLOGENIC PERIOD IN SOUTHERN SONGLIAO BASIN

The paleoenvironment in the metallogenic period of oil shale controls the organic type and abundance of oil shale, which is important for research of the origin and enrichment regularity of oil shale. In southern Songliao Basin, the oil shale formations are generally stable deep lake to semi-deep lake facies. The characteristics of trace elements are sensitive to the changes of ancient environment. Therefore, the contents of trace elements in oil shale and their ratios can be used to restore the paleoenvironment of oil shale in metallogenic period. This article, through test of more than 20 trace elements and analysis for their ratios of the oil shale samples from southern Songliao Basin, restores the paleoenvironment of the Qingshankou Formation and Nenjiang Formation. The results show that the oil shale in the metallogenic period experienced a warm humid-subhumid and dry heat climate, in a reduction environment of brackish water. To compare with the counterparts of Nenjiang period, the climate and salinity changes of Qingshankou period are more stable, with a slightly drier climate and a higher salinity.