铀曲线在沉积盆地古环境反演中的应用

由于地球化学及古生物指标有限,对沉积盆地古环境进行高分辨率反演是一个难度较大的地质课题。对东营凹陷牛38井自然伽马能谱曲线中的铀含量曲线进行了分析,认为此值与该井地球化学测试所获得的有机碳值有着良好的对应关系,表明铀值可以作为有价值的古环境研究参数,铀曲线可以作为重要的古环境研究工具。铀值升高,代表气候潮湿性增强,水体加深;铀值降低,反映气候潮湿性减弱,干燥性增强,水体变浅。运用水深函数、能量函数及水体动荡函数对铀值进行方差分析,可以更好地反映古水体环境的变化。研究表明,牛38井沙三段中自下而上气候潮湿程度降低,水体能量逐渐增强,水体逐渐变浅。

Application of uranium curve to paleoenvironment inversion in sedimentary basin

Paleoenvironment recovering with high-resolution is an important and difficult task for the finity of the information from geochemistry and paleontology. The value of uranium from natural gamma spectrometry curve has good correlation with the contents of carbon organic by geochemistry testing of Niu-38 well in Dongying Depression. It is shown that the value of uranium can act as a parameter for paleoenvironment research, and uranium curve is an important means for paleoenvironment recovering. High value of uranium represents wet paleoclimate and deep water-body, and low value of uranium reflects dry paleoclimate and shallow water-body. The variance analysis for uranium value by the functions of deepness, energy and disturbance of water-body can reveal the changes of paleoenvironment better. The research shows that from the lower part to the middle part of the Member 3 of the Shahejie Formation, the wet degree of paleoclimate drops, and the energy of water body increases, and the deepness of water body descends.