塔中地区志留系柯坪塔格组沉积特征

Sedimentary Facies of Kepingtage Formation of Silurian System in Tazhong Area, Tarim Basin

在沉积学、矿场地球物理学、古生物学等学科的理论指导下,通过岩心观察,结合测井、录井、古生物遗迹、分析化验等资料综合分析认为:塔中地区志留系柯坪塔格组沉积灰色含沥青粉砂岩、绿灰色泥质粉砂岩、灰色中细砂岩、灰白色细砂岩及灰色含砾中细砂岩、灰绿色粉砂岩、泥质粉砂岩;发育低角度冲洗层理、波状层理、脉状层理、透镜状层理、流水波纹、楔状交错层理、大量的同生泥砾及泥质条带,砂泥岩薄互层,低砂地比且从盆地中心向盆地边缘逐渐降低的现象以及大量的生物扰动现象都反映了一种低能的潮坪沉积环境。在研究区柯坪塔格组主要识别出潮间带,潮下带,发育朝下砂坝、潮间下砂坪、潮间中砂泥混合坪等微相,并结合分析化验资料讨论了不同沉积微相与油气的关系。

Under the theoretical guidance of sedimentology, geophysics, and palaeontology, based on the analysis on cores, well logs, log data, palaeontologic traces, it is known that the sedimentary system of tidal flat were developed in the Silurian System Kepingtage Formation of Tazhong Area, Tarim Basin. The Kepingtage Formation includes grey-bitumen siltstone, greenish gray politic siltstone, gray medium-fine sandstone, gray medium-fine pebbled sand and developed feathering cross bedding, wave bedding, lensing bedding, thin sand and mudstone interaction layers, and low ration of sand to strata. Especially, the phenomena of the descending distribution from the central area to the margin of the basin and a great deal of feeding and dwelling trail of palaeontologic, all of these phenomena reflect an environment of tidal flat. The Kepingtage Formation is mainly in intertidal zone, subtidal zone, developing microfacies, such as subtidal sand jetty, sand-mud mixed flat of intertidal, and sand flat of lower tidal. Combined with analysis of laboratory data, the relationship between these microfacies and the distribution of oil has been discussed.