济阳坳陷古近纪孢粉与层序地层

在陆相盆地中,基底沉降、沉积物供给和气候控制着基准面变化和层序发育,而气候的变化造成植被的变化,即造成了植被所产生的孢粉组合的变化,层序地层与孢粉组合有着密切的联系。首先根据孢粉母体植物生长的环境来恢复古气候,然后与综合岩性、电性及地震等资料在济阳坳陷古近系划分出的1个一级层序、4个二级层序、10个三级层序相对照。结果表明,利用孢粉组合特征进行层序地层学研究是可行的;牛38井沙三段中连续取芯井段,根据孢粉可以划分出湖侵体系域和湖退体系域2个三级层序,依据主要孢粉属种的变化,进一步划分出17个次级层序,与高精度层序地层对应。在资料丰富的情况下,可以运用孢粉组合变化进行高精度层序地层学分析,以提高区域地层对比的精度。

THE PALEOGENE PALYNOLOGY AND SEQUENCE STRATIGRAPHY OF IN THE JIYANG DEPRESSION

In continental basins, base level and sequence stratigraphy is controlled by tectonic movement, climate, and sediment supply. Climate is also a major controlling factor on vegetation and palynological assemblage. Thus, sequence stratigraphy and palynological assemblages may be related. This study focuses on the palynology and sequence stratigraphy of the Paleogene successions in the Jiyang Depression. Paleogene climate was reconstructed using palynological data. The palynological data was also correlated with sequence stratigraphic data from one first-order, four second-order, and ten third-order sequences. This study shows that palynological data can be used in sequence stratigraphic division of Paleogene successions in the Jiyang Depression.Using palynological data, we recognized two third-order sequences, as well as their lacustrine transgression and regression system tracts in the Niu 38 Well which penetrates the middle Es_3 Member. These two third-order sequences can be further divided into, on the basis of palynological data, 17 parasequences. This study shows that palynological data can assist in achieving high resolution in sequence stratigraphic division and regional correlation.