合肥盆地白垩纪层序地层格架、沉积体系配置及演化

Framework of Sequence Stratigraphy,Sedimentary System and Evolution of Cretaceous Hefei Basin

合肥盆地的白垩系是叠置在侏罗纪前陆盆地上的断陷构造层,其层序地层及沉积演化研究是油气勘探的重要环节。综合应用横跨盆地二维地震剖面、测井、岩芯、露头及其它分析化验资料,对合肥盆地白垩纪的地层进行了层序地层界面的识别、划分,建立了该期地层格架。共划分出一级层序:构造层序界面(构造层序)界面2个:SBK1(TK1)、SBE(TE);二级层序(层序组)界面1个:SBK2(TK2);三级层序(层序)界面4个:SBK11(TK11)、SBK12(TK12)、SBK13(TK13)、SBK21(TK21)。在此基础上建立了合肥盆地白垩纪层序地层格架及沉积演化阶段:早白垩世层序组(包括朱巷组和响导铺组层序组):为西缓超东陡深的不对称箕状断陷格局,西南部和北西部各发育一个大型冲积扇—冲积平原—三角洲平原带,西南部冲积扇—冲积平原大部分已经被剥蚀殆尽;东部和东北部发育一系列扇三角洲构成扇三角洲平原(裙),两者之间为滨浅湖—半深湖—深湖。晚白垩世层序组(张桥组层序组):北断南超的格局占主导,早白垩世时期的大型三角洲体系域已经不复存在,代之而起的是北部发育较大规模的扇三角洲平原;而南部或西南部冲积扇—冲积平原—三角洲平原带已经大为缩小到信阳—舒城断裂北缘。

According to seismic, well-logs, outcrop ＆ cores data, we identified sequence stratigraphy boundarys. Cretaceous-Paleogene strata can be recognized as 3 first-order sequence, 1 second-order sequences and 4 third-order sequences. Based on the principle of base level cycles, the author distinguished ＆ established sequence stratigraphy framework, sedimentary system setting ＆ evolution in Cretaceous-Paleogene. That is： 1 ） Early Cretaceous sequence series（Zhuxiang ＆ Xiangdaopu Formations） ： a semi-graben basin which onlapped in the west ＆ faulted in the east, developed great scale alluvial fan-alluvial plain-delta plain on the western-northern ＆ western-southern respecially. On eastern ＆ eastern-northern growth aseries fan-deltas ＆ shore semideep-deep lacustrine. 2） Late Cretaceous sequence series（Zhangqiao Formation） ： similar with Early Cretaceous basically,buta semi-graben basin which onlapped in the south ＆ faulted in the north more salience. 3 ） Paleogene Sequence series （Dingyuan Formation ）： The north of Feizhong fault uplift since tectonic movement so that bisect the basin, Dingyuan depression on the north and Shucheng depression on the south.