In order to study the sedimentary characteristics of Yanchang Formation in Nanliang area,the sedimentary system and sedimentary model of Triassic Chang 6 in Nanliang area of Ordos Basin are ex-plored from the data of drilling core observation,analysis of light and heavy minerals and well logging interpretation.The results show that K2,K3 and K4 sets of mudstones are used as marker layers in the Chang 6 reservoir of the Triassic Ordos Basin,and the reservoir is divided into three small layers ac-cording to the analysis method of sedimentary cycle characteristics revealed by logging.The analysis of light and heavy minerals confirms that the provenance of the Chang 6 subsection in Nanliang area is predominantly controlled by a northeast provenance,with its primary source derived from high-grade metamorphic rocks and volcanic rocks of Archean age in the Daqingshan and Yinshan areas.The sedi-mentary facies within the Chang 6 subsection area are primarily influenced by delta deposits originating from this northeast provenance.Consequently,the sand bodies developed during the Chang 6 period ex-hibit a banded distribution extending from northeast to southwest.It is concluded that the area of the Lake Basin Yanchang Formation in Ordos Basin decreased gradually during the Chang 6 depositional period,with a contraction of the delta sedimentary range towards the center of the basin.The develop-ment of delta front subfacies,deep lake sub,and shallow lake subfacies occurred northeast to southwest during the Chang 6 period.Turbidity current deposits are formed in response to water flow and gravity due to sediment collapse in the slope area of the delta front.
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