鄂尔多斯盆地镇北地区长3油层组物源及沉积体系

对鄂尔多斯盆地镇北地区上三叠统延长组长3油层组砂岩开展了碎屑组分、岩屑类型、重矿物组分等分析，结果表明：研究区西部富含长石、沉积岩碎屑和石榴子石，南部富含岩屑（特别是火山岩碎屑）和电气石，东北部富含石英、变质岩碎屑和锆石。碎屑组分的 Dickin-son 三角图解显示，南部物源区构造背景主要为再旋回造山带，西部除再旋回造山带外，还有来自基底隆起的物源。西部可能为近物源、坡度较大、沉积物成熟度较低的陡坡型辫状河三角洲，南部可能为远物源、坡度较小、沉积物成熟度较高的缓坡型辫状河三角洲，二者大致呈南西－北东向展布，交汇于镇167－庆25－镇268－镇255－西85井一线以东。

The provenance and depositional systems of the Upper Triassic Chang-3 oil formation in Zhenbei area,Ordos Basin,China

The analysis of clastic composition,types of debris and heavy minerals of the sandstone from the Upper Triassic Chang-3 oil formation in the Zhenbei area of Ordos Basin indicates that the sandstones in the west region are rich in feldspars and sedimentary rock debris with garnets,the sandstones in the south region are rich in volcanic debris with tourmalines and the sandstones in the northeast region are rich in quartz and metamorphic debris with zircons.Dickinson triangular plot reveals that in the south area,almost all of provenances come from recycled orogen,but in the west area,the provenances come from recycled orogen and basement uplift.It indicates that the west area is close the provenance with steep slope,low deposit maturity of braid river delta,and the south area is far away from provenance with gentle slope,higher deposit maturity of braid river delta.Two provenances form southwest-northeast trending banded distribution depositional systems converging on the Zhen167-Qing 25-Zhen 268-Zhen 255-Xi 85 wells of east line.