松辽盆地反转构造与油气田分布

INVERSION STRUCTURES IN RELATION TO OIL AND GAS FIELD DISTRIBUTION IN SONGLIAO BASIN

松辽盆地是晚中生代特大型裂陷盆地之一，其演化依次为裂谷期、后裂谷期和压陷期。在此过程中有三次构造反转，第一次发生于裂谷期为负反转，与断陷的形成有关。第二次和第三次分别发生于裂谷期末和后裂谷期末均为正反转，使盆地原型改造。负反转是早期的冲断层（系）再活动顺倾向上盘下滑。正反转过程与其相反并形成断弯和断展褶皱。松辽盆地前新生代构造格架在第三次反转中形成，平面上沿北北东－北东方向成带、变形强度自东而西、自南而北减弱，且与油气田分布有关。

Songliao basin is one of giant rift basins formed in the late Mesozoic.Its evolution represents successively rifting stage,postrifting stage and compression-subsidence stage.During its evolution process,there were three times of tectonic inversion:the first one occurred in the rifting stage,being a negative inversion related to the forming of fault depressions;the second and third ones occurred respectively at the end of the rifting stage and at the end of postrifting stage,both being positive inversions,which remoulded the protobasin.The negative inversion represented the reviving activities of early thrust faults(system)with upthrows sliding downward along the trend. The positive inversion process was contrary to the negative one,formed fault-bend and fault-propagation folds.The Precenozoic framework of structures in Songliao basin formed in the third inversion,horizontally forming structural belts along the trends NNE-NE with transformation intensity weakening from east toward west and from south toward north,and also showing a relationship with the distribution of oil and gas fields.