东濮凹陷古沉积环境及其对有机质丰度的影响

Paleo-sedimentary Environments in the Dongpu depression and their Impact on Organic Matter Abundance

东濮凹陷南北古沉积环境、有机质丰度差别巨大,运用有机地球化学和微量元素等多种方法对东濮凹陷沙河街组古沉积环境及其对烃源岩有机质丰度的影响进行了研究,结果表明:东濮北部为典型的咸水、还原环境;南部为淡水-微咸水、弱氧化环境。古沉积环境对有机质丰度起决定性作用:古盐度越高,还原性越强,有机质丰度越高。在此基础上,对北部盐岩发育区有机质富集的原因进行了分析:水生生物来源和闭塞强还原环境是有机质富集的主要原因。

In the Dongpu depression, enormous differences are present in paleo-sedimentary environments and organic matter abundance between its northern and southern parts. This study analyses its paleo-sedimentary environments and organic matter abundance using organic geochemical and microel-ement methods. The results show that the northern depression is a typical environment of saline water and reduction, while the southern part is an environ- ment of fresh-brachish water and weak oxidation. Paleo-sedimentary environments play a critical role on organic matter abundance. With the higher palaeo- salinity, the reducibility becomes stronger, and the organic matter abundance becomes higher. Based on this, we analyze the reason for the accumulation of the organic matter in the northern Dongpu depression where salt rock developed well and suggest that the aquatic organisms and the strong reducing envi-ronment are responsible for the organic matter accumulation.