松辽盆地南部拗陷期湖盆底形演化及充填序列

Relationship between bottom morphology of lake basin and filling sequence during depression period in the southern Songliao Basin

根据地震、钻井、岩心及测井资料,将松辽盆地南部青山口组三段—嫩江组一段划分为青三层序、姚家层序和嫩一层序。基于地层等时格架,应用回剥法经去压实和古水深校正,对松辽盆地南部湖盆底形特征进行了恢复。研究结果表明,松辽盆地南部拗陷期湖盆坡折带的发育程度受控于盆地的差异沉降以及沉积物供给速率,随着大地热流值的逐渐降低,湖盆坡折越来越不明显;而坡折带的发育程度对盆地的充填序列和沉积格局有重要影响。其中,青三层序坡折带发育明显,湖盆表现为深水拗陷沉积;姚家层序坡折发育不明显,表现为宽浅氧化湖盆;嫩一层序湖盆底形平缓,受湖侵影响,表现为广阔深水湖盆。

Based on the seismic, drilling, core and logging data, the sequence stratigraphy framework from the Member 3 of Qingshankou Formation to the Member 1 of Nenjiang Formation was divided into three sequences of Qing-3, Yaojia and Neng-1. On the basis of the isoehronous stratigraphy framework, the back-stripping inversion method was applied to paleoburial depth reconstruction and paleobathymetric correction. The paleogeomorphology at the bottom of the southern Songliao Basin was rebuilt. The bottom shape of the lake basin and the deposit supply controlled the development of the slope break belt. The bottom of the lake basin had no significantly change with the decline of the geothermal flux value. The development of slope break belt played very important role in the formation of filling sequences and facies tracts of the lake basin in the southern Songliao Basin. The Qing-3 Sequence was of obvious slope break resulting in deepwater deposition. The Yaojia Sequence was not obvious and showed the wide and shallow oxidized lake-basin. The Neng-1 Sequence was a broad deepwater lake-basin with a gentle bottom.