陆盆层序地层研究的思路

Thoughts on the Study of Continental Sequence Stratigraphy

根据陆相地层层序发育的特点,冲积扇、河流、三角洲或湖泊沉积环境,均受地层基准面控制,地层基准面穿越旋回控制着陆相环境重大层序分布。根据不同时间间隔的基准面穿越旋回序次,可将陆相层序划分为盆地充填层序、构造层序、层序、亚层序及小层序5个级别。每个层序(三级)根据基准面的波动可划分为基准面上升沉积体系域和基准面下降沉积体系域,然后可进一步根据亚层序组的叠置特征进行细分。

This paper discusses the basic principle of continental sequence division. The authors suggest that the stratigraphic base level is a unifying concept in analysis of continental sequences and the base level transit cycle is control of the change of accommodation as well as distribution of major sequences. According to the development characteristics of the terrigenous successions, the conti- nental sequences can be divided into five orders; the basin-fill sequence, tectonic sequence, sequence, subsequence and microsequence. They are interpreded to be formed during the time-intervals of 60-120 Ma, 20-40 Ma, 0. 5-5 Ma, 0. 1-0. 5 Ma and <0. 1 Ma respectively, representing different ranks of base level transit cycles. Based on the general characteristic that the internal textures of continental depositonal sequences are controlled by the transit cycles, two system tracts can be easily idenfied, i. e. the system tract of base level rise and systems tract of base level fall. According to the above-mentioned principle the authors divide the Cretaceous System in Jiangsu into three tectonic sequences and the Middle Cretaceous Gecun Formation into five depositional sequences.