Formation and Sedimentary Model of Shallow Delta in Large-Scale Lake . Taking from Cretaceous Quantou Formation in Sanzhao Sag, Songliao Basin
详细信息
- 责任者：Zhu Xiaomin (State Key Laboratory of Petroleum Resources and Prospecting ; China University of Petroleum (Beijing) ; Beijing 102249 ; China) ; Liu Yuan
- 刊名：Earth Science Frontiers
- 出版年：2012
- 卷期：19(1)
- 关键词：砂体 ; sand bodies ; 浅水环境 ; shallow-water environment ; 沉积相模式 ; sedimentary facies model ; 松辽平原 ; Songliao Plain
- 页码：p.89-99
- 图表：7 illus., 22 refs.
- 分类号：1003
- issnNo：ISSN1005-2321
- isbnNo：CN11-3370/P
摘要
The research of some core,logging,seismic data from Quantou Formation in Sanzhao Sag has been finished and some Geological ideas have been got,that is,the provenance of Sanzhao Sag was located in the north and southwest of Songliao Basin during the period of Quantou Formation,and the geological conditions were favorable for the formation of the large-scale shallow delta:the basement sank stably and the palaeotopography was gentle and smooth slope;the physical weathering was strong due to the arid palaeoclimate(up to 37℃);the lake level changed cyclically because of two cycles of palaeoclimate change from arid to humid;the lake water was shallow less than 10meters and lake level changed obviously.The shallow delta of Sanzhao Sag has obvious characteristics,that is the finer grain size,plenty of sedimentary structures formed by strong hydropower,wide purple mudstone with lots of bioturbation structure,several non-continuous normal cycles wertically,imbricated progradation seismic facies,large scale sandbody distribution with low percentage of sandstone to mudstone,and very unique distributary channels with few mouth bars.The sedimentation of the shallow delta was controlled by the climate change.When it was dry,the lake shrank,resulting in branched delta and branched distributary channels which were broad and shallow;the length of channels was more than 20km,the width from 800to 1 800m,the average thickness of individual layer was 2.3meters,and the average percentage of sandstone in strata was 35%.When it was wet,the lake expanded,the river branched off diverted frequently due to the lake water obstruction,formed reticular distributary channels that were narrow and deep,the length of the channel was less than 15km,the width from 500to 1 600m,the average thickness of individual layer was 2.8m,and the average percentage of sandstone in strata was 40%.Therefore,the sandbodies of distributary channels are widely distributed,overlapped vertically,and continued laterally,and form favorable lithologic reservoirs.