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江汉盆地荆沙组为大套红色砂泥岩,无明显标志层,它与上覆潜江组的接触关系长期未能解决。本文采用泥岩压实作用研究了潜江凹陷及江陵凹陷北半部荆沙组与潜江组的接触关系,发现在其接触面附近的泥岩压实曲线有四种偏离正常趋势的异常类型。经分析认为,这种异常现象是因沉积间断或剥蚀,使接触面产生的次生孔隙带所造成的,从而为“荆沙剥蚀面”区域性的存在提供了依据。
The Jingsha Formation in the Jianghan Basin is a large set of red sandstone and mudstone with no marked layer. Its contact with the overlying Qianjiang Formation has not been solved for a long time. In this paper, the contact relationship between the Jingjian Formation and the Qianjiang Formation in the northern half of Qianjiang Sag and Jiangling Depression is studied by using the compaction of mudstone. There are four abnormal types of mudstone compaction curves near the contact surface, which deviate from the normal trend. The analysis shows that this anomaly is caused by the discontinuous deposition or denudation of the secondary porosity caused by the contact surface, which provides a basis for the existence of the regional “erosion of Jingsha surface.”