鄂尔多斯盆地晚三叠世延长组长6期湖盆坡折带特征及其地质意义

Characteristics of Slope Breaks and Its Implication on Petroleum Geology in Yanchang Formation Chang 6 (Late-Triassic) of Ordos Basin

鄂尔多斯盆地晚三叠世湖盆西南缘及东北缘发育典型坳陷型湖盆坡折带。研究表明,在北东缘具有多级缓坡坡折带特征,坡度1°～3°,宽度15～25km;西南缘具有单一陡坡坡折带特征,坡度3°～5°,宽度10～20km。由于受湖盆收缩原因影响,坡折带平面展布局部会发生变化。与此同时,坡折带在对地层的超覆叠置、岩性纵向组合以及沉积体的纵横向展布上均具有重要的控制作用。以坡折带特征研究为基础,建立坡折带控制非构造圈闭展布模式,对于指导鄂尔多斯盆地晚三叠世地层的油气勘探具有重要意义。

Depressed-type slope breaks was developed in the southwest and northeast margin of the Late-Triassic Ordos Basin.In the northeast margin,the slope breaks were characterized by multistage and gentle,with grade of 1-3 and width of 15~25 km;In the southwest margin,the slope breaks were characterized by monolithic and steep,with grade of 3-5 and width of 10~20 km.Variations of slope breaks distribution were partly affected by the shrinkage of lake basin.However,slope controls formation overlapping,lithologic association and distribution of sedimentary system.To build distribution modeling of slope-nonstructural trap based on the research of slope break characteristics plays an important role in exploration activity of the Late-Triassic Ordos Basin.