鄂尔多斯盆地胡尖山地区长9—长8油层组物源及沉积体系分析

为了查明鄂尔多斯盆地胡尖山地区上三叠统延长组长9—长8油层组沉积体系的分布格局,利用砂岩岩石学特征,轻、重矿物组合特征,砂分散体系制图,沉积构造特征等对研究区物源方向、母岩类型及沉积微相进行研究.结果表明,研究区主体受到东北物源的影响,但长8段研究区西部小范围受到西北物源影响,2个方向的物源在王盘山以东地区发生了交汇.其母岩为盆地北部阴山、大青山的变质岩、花岗岩以及阿拉善古陆的变质岩.胡尖山地区长9—长8油层组发育曲流河三角洲相沉积,北部为三角洲平原亚相,向南过渡为三角洲前缘亚相.可以识别出北东-南西向安边曲流河三角洲沉积体系及北西向盐池-定边曲流河三角洲沉积体系.

Analyses of the provenance and the depositional systems of Chang 9-Chang 8 strata in Hujianshan aea, Ordos Basin

For determining the distribution of the depositional systems f the Chang 9-Chang 8 strata in the studied area,the provenance directions,the parent rock types and the depositional systems in the studied area are studied according to the petrographical characteristics of the sandstone,the combination feature of light mineral with heavy mineral,the distribution diagram of the sand system and the structural feature of the deposition.The results show that,the studied area is affected mainly by the northeastern sediment source,while a small part in the western area is affected by the northwestern sediment source,and the two sources meet to the east area of Wangpanshan.The parent source rocks of the studied area are the metamorphic rock and magmatic rock from Yinshan and Daqingshan and the metamorphic rock from Alxa ancient land in the north of the basin.Meandering river delta facies develops in Chang 9-Chang 8 strata in Hujianshan area,and delta plain subfacies translate to delta front subfacies from the north to the south.Anbian meandering river delta system in northeast——southwest and Yanchi-Dingbian meandering river delta system in north——west can be identified.