高分辨率层序地层学特征及砂岩型铀成矿作用——以二连盆地白音乌拉地区赛汉组为例

High-resolution sequence stratigraphic character and sandstone-type uranium ore formation——A case from Saihan Formation in Baiyinwula area,Erlian Basin

高分辨率层序地层学已经被广泛应用于油气勘探与开发,并取得了丰硕的成果,但在二连盆地砂岩型铀矿床勘探方面的应用还只是刚刚起步。本文应用高分辨率层序地层学理论,以典型钻孔为例对白音乌拉地区含矿建造赛汉组进行了沉积旋回的划分和剖面对比,识别出一个长期旋回(LSC1)、两个中期旋回(MSC1、MSC2),在此基础之上结合该地区砂岩铀矿化特征,提出层间氧化带主要发育在MSC1的上升半旋回中,矿体主要赋存于低可容纳空间下形成的河道砂体中,且认为这类砂体厚度适中(10～15m)空间上具有一定的连通性,泥质夹层薄(<3m),自身渗透性好,富含有机质,有利于层间氧化带的发育。

High-resolution sequence stratigraphy and development, many achievements have been high-resolution sequence stratigraphy is applied has been applied widely in the petroleum exploration achieved. However, it is in the beginning stage that to explore the sandstone-type uranium deposits in Erlian Basin. By applying principles of high-resolution sequence stratigraphy and taking typical boreholes as an example, sedimentary cycles of Saihan Formation, the ore-bearing formation in Baiyinwula area are divided and correlated through cross sections. One long-term cycle （LSC1）, two middle-term cycles（MSC1, MSC2） have been identified in this study. Based on this and combined with the mineralization character of sandstone uranium deposits in this area, it is presented that the interlayer oxidation zone is developed mainly in the rising hemicycle of MSC1 and uranium ore bodies predominantly in channel sand bodies that were developed in the system tract with low accommodation; furthermore, it is recognized that these sand bodies are moderate （10-15m） in thickness, fairly good in interconnectivity, relatively thin （〈3 m） with the argillaceous interbed, and good in permeability, abundant in the organic matter and thus it is favorable for the development of the interlayer oxidization zone.