松辽盆地大庆长垣以东地区深层断陷构造特征及成因分析

THE DEEP FAULT DEPRESSIONS AND THEIR GENESIS ON THE EAST OF DAQING PLACANTICLINE IN SONGLIAO BASIN

大庆长垣以东地区断陷的发育规模较大,是松辽盆地北部深层天然气勘探的重点地区.西断东超的箕状断陷是长垣以东地区断陷的重要特征.晚侏罗世—早白垩世早期,各控陷断裂均经历了由多个区段独立发育、相互作用、最终连为一条断裂的动态发育过程.深层断陷的发育经历了火石岭组的初始断裂期、沙河子组的强烈断陷期和营城组的断陷萎缩期,其间遭受了多期重要的改造作用.伸展型构造是松辽盆地油气成烃、成藏的根本要素,也是油气较富集的重要因素.

The extensional fault-depressions occurring broadly on the east of Daqing placanticline are the advantageous areas for natural gas exploration in the deep-layer of northern Songliao Basin.The fault-depressions are characterized by half-graben basins.From Late Jurassic to Early Cretaceous,the depression-controlling faults experienced the developing processes from independence,interaction to the unification.The deep fault-depressions in northern Songliao Basin went through three developing stages,i.e.the initial faulting stage in Huoshiling Period,the strong downfaulting stage in Shahezi Period,and the fault-depression depauperization stage in Yingcheng Period.The fault-depressions also underwent several compressive tectonic activities.The extensional structures provide excellent traps for oi1 and gas accumulations in the Songliao Basin.