陇东地区三叠系延长组是由顶、底两个区域性不整合或假整合界面组成的一个超长期旋回。在该构造层序形成发展的沉积演化旋回中,依据次一级的构造、气候、物源供给条件及湖平面升降等变化,可将上三叠统延长组分为区域上分布稳定的4个长期旋回。在此基础上,采用层序一盆地系统的动态成因分析方法,对陇东地区延长组进行了层序充填动力学研究,认为构造沉降的脉动性、气候的旋回性以及由此引起的沉积物供给的差异性控制了4个长期旋回的发育与演化。文中,进一步探讨了盆地演化过程中的层序充填动力学响应,指出湖盆演化的不同时期形成不同的沉积亚相组合、不同类型的沉积物以及不同的层序叠加样式。
Triassic Yanchang Formation in Longdong area is a super-secular cycle bounded on top and base by regional unconformities/disconformities. It can be divided into four secular cycles according to subsidiary structure, climate, provenance condition and fluctuation of lake level during the sedimentary evolutionary cycle of the sequence. Sequence filling dynamics of Yanchang Formation is studied through dynamic genesis analysis of the sequence-basin system. It is believed that the development and evolution of the 4 secular cycles would have been controlled by pulsativity of tectonic subsidence, cyclicity of climate and the resulting differences in sediment yield. The responses of sequence filling dynamics occurring during evolution of the basin have further been discussed in this paper. It is pointed out that there are different combinations of sedimentary subfacies, different types of sediments and different superimposition patterns of sequences in different evolutionary periods of the lake basin.