松辽盆地东南隆起区古地貌恢复方法与效果

Restoration Methods and Effects of Paleogeomorphology in the Northeastern Part of the Southeast Uplift of Songliao Basin

松辽盆地东南隆起区在晚白垩世末期经历了多期构造抬升运动,导致原始沉积地层破坏严重,致使对该区古地貌及沉积演化特征认识不明确。为了恢复东南隆起区北部的古地貌,以回剥-填平补齐法为基础,采用多项式拟合的方法对地层结构进行外延,然后基于井震联合法求取地层残余厚度,结合地层结构外延法计算地层剥蚀量,最后拟合出有效的时深转换公式,并以此为基础实现了研究区的古地貌恢复。应用结果表明,该区泉头组和青山口组沉积演化过程相对稳定,剥蚀区零散分布,剥蚀量较小;姚家组在研究区中部构造相对高隆,剥蚀相对强烈;嫩江组因区域构造抬升导致受到剥蚀作用最为强烈,在长春岭背斜、钓鱼台隆起北部及青山口背斜南部等地剥蚀现象较为显著。以上研究成果对研究区后续物源分析、有利区预测等研究提供了基础。

The southeast uplift area of Songliao Basin experienced multi-stage tectonic uplift at the end of the Late Cretaceous, which resulted that the original sedimentary strata was damaged in serious and the palaeogeomorphology and sedimentary evolution characteristics of the area couldn’t be understood clearly. The method of stripping and filling was as the based method used to restore the paleogeomorphology in the northern part of the southeast uplift area, and the polynomial fitting method was used to improve the epitaxy of stratum structure. Then, the superimposed well seismic method was used to calculate the residual stratum thickness, and the denudation amount calculated by the epitaxy of stratum structure. Finally, fitting the effective time-depth conversion formula, the paleogeomorphology restoration in the study area based on this was successfully restored. The result shows that the sedimentary evolution process of Quantou formation and Qingshankou Formation is relatively stable, and the denudation area is scattered and the amount of denudation is small. In the middle of the study area, the structure of Yaojia Formation is relatively high and denudation is relatively intense. The Nenjiang Formation has been the most strongly eroded due to regional tectonic uplift, and the denudation is more obvious in the Changchunling anticline, the northern part of the Diaoyutai uplift and the southern part of the Qingshankou anticline. These results provide a basis for subsequent provenance analysis and favorable area prediction in the study area.