江汉盆地白垩系沉积相与沉积演化

在对江汉盆地露头剖面野外实测、钻井及分析化验资料综合研究的基础上,运用层序地层学、沉积学和测井地质学原理,识别了白垩系层序及沉积相类型、沉积特征.研究表明,受燕山期幕式构造运动的影响,白垩系可划分为两个构造层序,主要发育冲积扇、辫状河、辫状河三角洲和氧化型湖泊四种主要沉积相类型;早白垩世,由于拉张断陷强度较弱,仅在盆地边缘断裂前缘的局部地区发育一套粒度较粗的冲积扇-辫状河砂砾岩沉积;至晚白垩世,在区域引张力的作用下盆地整体拉伸断陷,从盆缘往盆内方向依次发育冲积扇-辫状河-三角洲-氧化型湖泊沉积,构成一个自下而上粒度由粗变细的沉积序列.

CRETACEOUS SEDIMENTARY FACIES AND THE EVOLUTION IN JIANGHAN BASIN

Based on comprehensive outcrop section measurement, drilling and analysis data, the Cretaceous sequence and its types of sedimentary facies and sedimentary characteristics in Jianghan Basin are systematically studied by using the theories of sequence stratigraphy, sedimentology and log-geology. It is shown that there are two tectonic sequences in Cretaceous affected by Himalayas curtain-like mountain formation movement, Cretaceous is mainly comprised by alluvial fans, braid river, braid river delta and exotic lake facies. In early Cretaceous, alluvial fans and braid rivers were only located in the front part of the fault in the basin because of weak depression and faulting; In late Cretaceous, the basin was totally depressed and faulted because of the aerial expansion, from its margin toward its center, the facies developed from alluvial fans, gradually to braid rivers and braid river deltas or exotic lake, forming a up-fine sequence.