东濮凹陷文南—刘庄地区沙二下亚段浅湖风暴沉积

摘要

Storm deposit is a kind of special event deposit, and reveals palaeogeography and palaeoclimatology changes of certain period in certain region. Through the palaeogeography research and fine strata division, the evidence and characteristic of storm deposit of shallow lake in lower submember of member 2 of Shahejie Formation of Wennan-Liuzhuang Area, Dongpu Depression were discussed, and the sedimentary model of storm deposit was summarized. The results showed that deposition sequence of lake basin was mainly controlled by climate, so the frequent climate change resulted in the wide distribution and multi-period development of storm deposit; storm deposit mainly developed in lake transgressive system tract(TST) and highstand system tract(HST), and developed in deep water during the early deposit, and the distribution range enlarged during the later deposit; storm deposit, which could be the assistant mark for strata sequence division, generally occurred around the boundary of each sand group, and was taken as a event deposit with short term and isochronous; the sedimentary models of storm deposit mainly included class I and class II;class I storm deposit was similar to that developed in deep water, and developed A-D interval deposits which was similar to Bouma Sequence, but the granularity was thinner than that of storm deposit developed in deep water, and mostly developed in relatively deep water of flood-over-lake depositional environment; class II storm deposit did not develop the B and D interval deposits; when the storm stopped, if the storm flow was closer to the center of lake basin, the sedimentary characteristic was more similar to class I storm deposit, otherwise, it was more similar to class II.%风暴沉积是一种特殊的事件沉积,反映了区域特定时期的古地理环境和古气候变化.通过区域古地理研究和精细地层对比,探讨了东濮凹陷文南—刘庄地区沙二下亚段沉积时期浅湖风暴沉积证据及特征,在此基础上总结了风暴沉积模式.结果表明:沙二下亚段沉积时期湖盆沉积层序主要受气候条件控制,气候频繁变化导致风暴沉积广泛分布、多期发育；风暴沉积主要发育在湖侵体系域和高水位体系域,沉积早期发育在深水区,而到沉积晚期分布范围扩大；风暴沉积一般发生在每期砂组的边界附近,作为短期、等时的一种事件沉积,可以用来作为层序划分的辅助标志；研究区风暴沉积模式主要有Ⅰ类和Ⅱ类两种；Ⅰ类风暴沉积为类深水风暴沉积,发育A-D段沉积的类鲍马序列层序,但粒度要较深水风暴沉积细得多,多见于漫湖沉积环境相对深水区；Ⅱ类风暴沉积不发育Ⅰ类风暴的B和D段沉积；风暴流在风暴停止时越靠近湖盆中央,其沉积特征就越类似深水风暴沉积,反之则越类似Ⅱ类风暴沉积.