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.