摘要
立足于野外露头、钻井资料研究,结合室内薄片分析、微量元素测试等,运用沉积学、沉积地球化学等理论和方法,在鄂尔多斯兴县地区下二叠统山西组中,识别出了三角洲平原和三角洲前缘2种亚相及分流河道、泥炭沼泽、天然堤、决口扇、水下分流河道、分流间湾和河口砂坝7种微相,并发现研究区山一段主要发育三角洲平原亚相,山二段主要发育三角洲前缘亚相,且整体上山西组沉积期区内具有三角洲逐渐向南推进的沉积特征。研究区的聚煤作用研究表明,山西组煤层均形成于短期基准面上升的晚期,8#、7#、6#煤的聚煤作用主要发生在三角洲前缘分流间湾充填淤浅的泥炭沼泽环境,5#煤形成于三角洲平原泥炭沼泽环境;山二沉积段中富煤地带多与砂岩富集带相吻合,山一沉积段中煤层的厚度则与砂砾岩含量呈现负相关性。
On the basis of the field outcrop survey and drilling data, in combination with laboratory thin section observation and trace element analysis, the authors employed such means as sedimentology and sedimentary geochemistry to conduct investigation. The results show that, in the Lower Permian Sbanxi Formation of Xingxian area within Ordos basin, there exist 2 subfacies comprising deltaic plain and deltaic front and 7 microfaeies com- posed of distributary channel, peat swamp, natural levee, splay, underwater distributary channel, interdistribu- tary bay and channel mouth bar. The authors drew the sedimentary section of Shanxi Formation and compiled the sedimentary column of Shanxi Formation as well as Xiegou and Guanjiaya sections, which show that deltaic plain subfacies are mainly developed in Shan 1 Member whereas deltaic front subfacies are developed in Shan 2 Member of the study area. On the whole, during the deposition period of Shanxi Formation, the region showed a deposition process that the delta advanced southward gradually. The authors discussed the coal-accumulation process in the study area and pointed out that coals of Shanxi Formation were formed at the late stage of the short-term level ascending cycle. Coal-accumulation processes of 8^# , 7^# , 6^# coal seams occurred mainly in peat swamp that was developed in interdistributary bay of the deltaic front, whereas the deposition of 5^# coal seam occurred in peat swamp of the deltaic plain. The authors also analyzed the relationship between the thickness varia- tion of coal seam and the sedimentary environment in the study area. It is evident that the distribution of thick coal zones of the Shan 2 Member coincides with the distribution of sandstone-rich belt, and that the coal seam thickness is in negative correlation with the percentage of gravel rock in Shan 1 Member of the study area.
出处
《岩石矿物学杂志》
CAS
CSCD
北大核心
2013年第3期355-365,共11页
Acta Petrologica et Mineralogica
关键词
兴县地区
下二叠统
山西组
沉积相
三角洲沉积
聚煤作用
Xingxian area
Lower Permian
Shanxi Formation
sedimentary facies
delta deposit
coal-accumulation process