松辽盆地北部隐伏二叠系和侏罗系的初步研究

据50余口钻井揭露,松辽盆地北部隐伏的二叠系自下而上称杜尔伯特组(磨拉石)、一心组(残留海盆)、林甸组(火山弧)和四站组(大湖盆),是海西期阿尔泰型(增生弧型)造山带发育的记录,构造线为北东东向。侏罗系(主体为中侏罗统)大庆群由下部碎屑岩和上部蚀变火山岩组成,是古缝合线活化控制发育的燕山期陆内造山作用的磨拉石建造,构造线仍为北东东向,故侏罗系自内蒙东延入黑龙江省中-西部。晚侏罗世时松辽地区的磨拉石盆地闭合,中-酸性岩浆侵入活动仍十分活跃。据新的同位素年龄、化石和构造线方向等证据将火石岭组、沙河子组和营城组归为早白垩世早期,是北东向构造控制发育的松辽盆地断陷阶段的记录。文章列述了典型钻孔所见二叠系和侏罗系的岩石序列和地层分布,分析了其沉积—构造背景和演化,提出松辽盆地的基底是海西期增生弧型造山带,盆地早期的断陷伸展和火山作用是燕山造山带坍塌的地表反映。在此基础上讨论了早白垩世北东向新生构造在区域构造演化中的意义,探讨了前白垩系的油气远景。

A PRELIMINARY STUDY ON THE BURIED PERMIAN AND JURASSIC IN THE NORTHERN SONGLIAO BASIN

The fifty odd drilling wells in the northern Songliao Basin revealed that the buried Permian there consisted of,in ascending order,the Dorbod Formation(molasses),the Yixin Formation(relict marine basin),the Lindian Formation(volcanic arc) and the Sizhan Formation(large lacustrine basin),which was a development record of the Hercynian Turkic-type(accretion arc-type) orogen,with the structural line being NEE-striking.The buried Jurassic(main part being Middle Jurassic) Daqing Group was composed of lower clastic rocks and upper altered volcanic rocks,which was a molasses formation of the Yanshanian intracontinental orogenesis controlled by rejuvenated fossil(Hercynian) sutures,so that the structural line kept a NEE-striking,and the strata in Inner Mongolia stretched eastwards into central-western Heilongjiang.The molass basin in Songliao area closed in Late Jurassic,but the intermediate-acidic magmatism was still active.Based on new evidence of isotopic data,fossils and tectonic trending,the Huoshiling,Shahezi and Yingcheng Formations,as a record of fault-depressing stage of the Songliao Basin constrained by the NE-trending neogenic structure,should be in age of Early Cretaceous,instead of Late Jurassic.The paper described the typical stratigraphic succession of Permian and Jurassic in drilling wells and their distribution, analyzed the sedimento-tectonic settings,and represented the basement of the Songliao Basin being a Hercynian Turkic-type orogen(instead of an Early Precambrian craton),and the extension,fault-depressing and volcanism of early stage of the Cretaceous basin being a surface reflection of collapse of the Yanshanian intracontinental orogen.In addition,the paper discussed the NE-trending neogenic structure formed in Early Cretaceous and its significance in regional tectonic evolution,explored the oil-gas potentials of the pre-Cretaceous in Songliao and its adjacent areas.