Sedimentary environment of shallow-water delta and beach-bar of the Member 1 of Shahejie Formation in Lixian slope of Raoyang sag,Jizhong Depression |
| |
| Authors: | Ye Lei Zhu Xiao-Min Zhang Rui-Feng Xie Shuang-Hui Gao Yuan Tang Hong Qi Xue-Zhu Chen Ya-Qing |
| |
| Institution: | 1.College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China;2.PetroChina Huabei Oilfield Company,Hebei Renqiu 062552,China |
| |
| Abstract: | Shallow-water delta and beach-bar are not only the current research hotspots of sedimentology,but also the important sedimentary types of sand body for oil and gas exploration. The sedimentary environment controls the development and evolution of shallow-water delta and beach-bar. Based on the analysis of core,well,logging,spore-pollen fossils and trace elements,the types of sedimentary system and sedimentary environment of the Member 1 of Paleogene Shahejie Formation in the Lixian slope of the Raoyang sag,Jizhong Depression was studied integratedly. The results showed that: (1)Shallow-water delta and beach-bar deposits were mainly developed in the study area in the Member 1 of Shahejie Formation(Es1). The inner and outer shallow-water delta fronts predominated during the deposition of the bottom sandstone section of the lower sub-Member of Es1. Lake level rose and shallow-water delta retrograded,and beach-bar predominated during the deposition of the special lithologic section of the lower sub-Member of Es1. The lake level fell,and the delta that prograded to the center of lake. The main sedimentary body changed into the shallow-water delta during the deposition of the upper sub-Member of Es1. (2)The sedimentary evolution of shallow-water delta and beach-bar are controlled by sedimentary environment. During the deposition of the bottom sandstone section of the lower sub-Member of Es1,the study area was in a relatively arid subtropical climate,and the lake was in the relatively shallow oxidized and brackish setting,which was conducive for the development of the shallow-water delta. During the deposition of the special lithologic section of the lower sub-Member of Es1,large-scale lake transgression increased the lake level,while the provenance supply was limited in the study area. The lake changed into the reducing setting within the relatively humid climate and increased salinity,which was favorable for the formation of beach-bar. During the deposition of the upper sub-Member of Es1,the source supply was sufficient,and the study area was in the relatively humid subtropical climate. Meanwhile,the lake basin shrank,the lake level decreased. The relatively low salinity and oxidized fresh water setting was conductive for the deposition of the shallow-water delta. |
| |
| Keywords: | shallow-water delta beach-bar sedimentary characteristics sedimentary environment Shahejie Formation Raoyang sag Jizhong Depression |
|
| 点击此处可从《古地理学报》浏览原始摘要信息 |
| 点击此处可从《古地理学报》下载免费的PDF全文 |
|
