东濮盆地沉积岩的穆斯堡尔谱学研究

东濮盆地四口井的25个沉积岩样品的穆斯堡尔谱学研究结果表明,沉积岩样品中的主要含铁矿物相为黄铁矿、粘土矿物以及一些碳酸盐矿物。沉积岩中黄铁矿铁的相对含量与Pr/Ph和CPI之间存在着负相关关系,表明穆斯堡尔谱学方法所确定的黄铁矿铁的相对含量可以作为沉积岩形成时古环境分析的一项可靠指标。此外,东濮盆地铁白云石主要分布在一定深度范围之内,本文讨论了铁白云石的分布与沉积岩有机质成熟度之间的对应关系。

MSSBAUER SPECTROSCOPY STUDY OF THE SEDIMENTS FROM DONGPU BASIN

The sediments from Dongpu basin were studied by use of Mssbauer spectroscopy. The chemical states of iron and iron distribution among the different mineral phases in the sediments were determined. It was found that iron mainly present in pyrite., clay minerals and carbonates such as siderite, ankerite and calcite. The relative amount of iron in pyrite is related to pristane/phytane (Pr/Ph) and carbon prefence index (CPI). The nagative correlation between pyrite content and Pr/Ph and between pyrite content and CPI exist. This suggests that the relative amount of iron in pyrite in sediments can be used as an indicator for oxidizing-reducing environment.The results show that the environment of S_3~4 are reducing or strong reducing, and S_3~3 are reducing, while S_3~2 are in reducingweakly oxiding environment. The relative amount of iron in. different minerals have been determined as a function of depth in the wells. A comparison of-Mssbauer results with available organic geochemical analyses for the source rock maturity shows that the presence of ankerite in the sediments may be related to source rock maturity.