鄂尔多斯盆地中部湖相有机质沉积环境特征

在采用能量色散X射线荧光技术的测试过程中,受能量配置探索不足的影响,所测元素的数量往往较少,导致无法充分利用元素参数来刻画古沉积环境.此外,陆相有机质的来源包括河流输入有机质和水体生产有机质,如何对其进行定量区分尚存困难.针对能量色散X射线荧光技术的能量配置进行了改进,由此将精确测试的元素数量扩充到28个.选择鄂尔多斯...

Sedimentary environment of lacustrine organic matter in the central Ordos Basin

The numbers of measurable elements in lacutrine shale sampels by energy dispersive X-ray fluorescence （ED-XRF） technology are often limited due to insufficient energy configuration. This makes it difficult to fully restore the paleosedimentary environment for samples concerned. Furthermore， some lacutrine organic matter can be of river input origin or indigenously produced in lake water， quantitatively distinguishing one from the another is challenging. In this study， energy configuration of ED-XRF is improved to increase the number of accurately measurable elements to 28. Shale samples from the seventh member of Yanchang Formation （Chang 7） in central Ordos Basin are tested for geochemical characterization of organic carbon， major elements， trace elements and carbon isotopes. The results are used to restore the paleosedimentary environment of organic matter from Chang 7， including the water column， redox and productivity. A mathematical model is established to analyze the organic matter. The results show that the organic matter of Chang 7 shale is formed in fresh water with oxygen deficiency or anoxia， high paleoproductivity but a moderate primary productivity against a warm and humid climate background. For shale in the central Ordos Basin， organic matter is rather lake water produced than terrestrial input.