柴达木盆地鄂博梁Ⅲ号构造新近系沉积环境演化及物源分析

Provenance analysis and sedimentary environment evolution of the Neogene in Eboliang Ⅲ structure of Qaidam Basin

鄂博梁Ⅲ号构造为柴达木盆地大型构造之一,其中仅新近系下油砂山组圈闭面积即可达470km2。运用近3年来在该构造东西高点钻探的鄂深1、鄂深2及鄂7共3口探井的最新资料,通过岩石学、古生物学及地球化学等综合分析,对鄂博梁Ⅲ号构造沉积环境演化和物源方向进行了系统研究,取得了不同于前人的新认识。鄂博梁Ⅲ号构造新近纪沉积环境自上干柴沟期(N1)到狮子沟期(N23)是一个湖进、水体不断加深的沉积演化过程,与前期所认识的湖泊收缩、水体不断变浅的结论不同。鄂博梁Ⅲ号构造新近系沉积碎屑主要来自于阿尔金山物源区,自下而上具有较强的继承性,浅部地层受冷湖方向物源的影响而具有混源的特点。该研究取得的新成果为该区进一步勘探部署提供了理论依据,并取得了一定的勘探成效。

Eboliang Ⅲ structure is one of the macrostructures in Qaidam Basin with trap area up to 470, km2 in the Neogene Xiayoushashan Formation.In this paper,the authors studied the systematically the sedimentary environment evolution and provenance direction in Eboliang Ⅲ structure by using the new data of Wells Eshen 1 ,Eshen 2,and Eshen 7,which were drilled in succession at the east and west structural high points in recent three years.By synthetic analysis with petrology, palaeontology and geo-chemistry,some new points about the sedimentary environment evolution and provenance direction were obtained.The structure from the Shangganchaigou Age to Shizigou Age was under a deposition process with constantly deepening water,which was completely opposite to the previous viewpoint.Altun Mountains provenance provided main sedimentary clastics for Eboliang Ⅲ Structure.On this basis,the single well and multi well analysis has been developed to confirm the sedimentary evolution process,providing a theo-retical basis for further exploration and deployment,and obtaining the corresponding exploration effect.