晚中生代二连盆地吉尔嘎朗图凹陷地层和构造演化研究

二连盆地是中国东北重要的油气、煤炭和铀矿基地,吉尔嘎朗图凹陷是盆地最重要次级凹陷之一。吉尔嘎朗图凹陷的资源勘查工作已经持续了几十年,然而,至今凹陷形成和演化的过程仍缺少精细地刻画。通过磷灰石裂变径迹年代学分析、地震反射剖面分析,结合前人地层定年工作,对晚中生代吉尔嘎朗图凹陷地层和构造演化历史进行了研究。研究结果表明中侏罗世和早白垩世是凹陷的主要断陷期。但是,凹陷在晚中生代并不是始终处于伸展构造环境、凹陷至少在晚侏罗世晚期-早白垩世初(中侏罗统与阿尔善组沉积间歇期)、早白垩世中期(阿尔善组与腾格尔组沉积间歇期)、早白垩世中晚期(腾格尔组与赛汉组沉积间歇期)、早白垩世末-晚白垩世(赛汉组与新生界沉积间歇期)经历过短暂但强烈的挤压构造作用。

Late Mesozoic Tectonostratigraphic Evolution of the Jiergalangtu Sag in the Erlian Basin

Erlian Basin is one of the most important oil, coal and uranium-bearing basins in Northeast China, and the Jiergalangtu Sag is one of the subsidiary basins of the Erlian Basin. Despite decades of petroleum exploration, the tectonostratigraphic evolution of the Jiergalangtu Sag remains disputed. Based on newly obtained apatite fission-track ages and seismic reflection profiles, the present study carries out a detailed analysis of the Jurassic-Cretaceous evolution of the Jiergalangtu Sag. It is suggested here that the Jiergalangtu Sag is a polyphase extensional basin. The Middle Jurassic-Early Cretaceous syn-rift subsidence of the Jiergalangtu Sag was intermittent rather than continuous, and was punctuated by multiphase contractional deformation during the late Late Jurassic-earliest Cretaceous (prior to the deposition of the Aershan Formation), during the middle Early Cretaceous (after the deposition of the Aershan Formation and prior to the deposition of the Tenggeer Formation), during the middle-late Early Cretaceous (after the deposition of the Tenggeer Formation and prior to the deposition of the Saihan Formation), and during the latest Early-Late Cretaceous (after the deposition of the Saihan Formation).