松辽盆地大庆长垣形成时间的厘定及其地质意义

大庆长垣位于松辽盆地北部一级构造单元中央坳陷区内,是松辽盆地中隆升幅度最高、规模最大的背斜,由于其含有十分丰富的油气资源,长期以来备受瞩目,但其形成时间一直存在很大争议。通过对大庆长垣二维、三维地震剖面解析,应用生长地层理论,厘定大庆长垣的形成时间,并探讨其地质意义。研究发现:大庆长垣呈近NNE走向,为一个与近NWW—SEE向挤压作用有关的大型背斜。大庆长垣背斜北部嫩江组—明水组(T_1-T_(02))、中部嫩江组四段—明水组(T_(05)-T_(02))、南部四方台组—明水组(T03-T02)自构造高部位向低部位厚度逐渐增大,为与大庆长垣背斜隆升相伴沉积的一套生长地层;下伏地层在大庆长垣背斜顶部、翼部及两侧向斜部位厚度基本相等,具有前生长地层特征。大庆长垣背斜自嫩江组沉积初期受到近NWW—SEE向挤压作用开始隆升,一直持续到明水组沉积末期,但大庆长垣背斜不同构造部位的隆升时间、隆升速率及隆升高度都有所不同。松辽盆地晚白垩世的挤压作用可能与太平洋板块的俯冲作用有关,对油气的运移和聚集成藏有很大的影响。

Determination of Timing and Its Geological Significance of Daqing Placanticline in Songliao Basin

The Daqing placanticlineis the highest and largest anticline in the Songliao basin,which has been highly concerned for a long time because of its abundant oil-gas resources and the controversy for its formation time.On the basis of the detailed geological interpretation of 3D and 2D seismic profile in Daqing placanticline,with application of growth strata theory the timing and its geological significance of Daqing placanticline can be determinate.The study indicates that the Daqing placanticline is a large NNE-trending anticline due to a NWW-SEE direction compression.The growth strata contain Nenjiang-Mingshui Formation in the northern Daqing placanticline,Member 4 of Nenjiang FormationMingshui Formation in the middle of Daqing placanticline and Sifangtai-Mingshui Formation in southern Daqing placanticline.Based on seismic interpretations,the thickness of growth strata gradually increases from high position to low position of the structure and have characteristic wedge shaped sedimentation;The thickness of pre-growth strata are equal from high position to low position of the structure.The stage of nearly NWW-SEE compression in Songliao basin begun from the deposition of the Nenjiang Formation and ended to the deposition of the Mingshui Formation,leading to form the Daqing placanticline.The different part of anticline of Daqing placanticline has different timings,heights and rates.The stage of compression during Late Cretaceous in Songliao basin may be related to the subduction of Pacific plate.It also has significant influence for the migration and reservoir of hydrocarbon in Songliao basin.