摘要
新乡位于豫西北山地与豫东平原过渡位置,黄河冲积扇的不断发展以及第四纪早期的新构造运动对该区第四纪沉积过程产生影响。通过对新乡多个钻孔岩心进行系统性描述、年龄测试、沉积相分析以及钻孔地层间对比分析,结果显示:黄河冲积扇的发展及黄河主河道的南北向迁移,是研究区第四纪沉积过程的重要影响因素,研究区第四纪沉积相以河流相为主,横向上对比良好;多个场地的钻孔揭示研究区全新统厚度约10 m,平均年龄9.5 ka左右;更新统上部厚度约69 m,平均年龄129 ka左右;更新统中部厚度约55 m,平均年龄小于829 ka;更新统下部未见底。在第四纪早期,黄河冲积扇主河道在研究区西侧,尚未发育到新乡地区,对该区的影响较小,以细粒的泛滥平原沉积物为主;第四纪中期,黄河冲积扇快速向东部发展,河道迁移至研究区北东侧,沉积了明显的河流相,砂体厚度明显增加;第四纪中晚期,基本继承前期的河流相沉积,随着河道南迁,砂体含量有所下降。受到新构造运动的影响,新乡地区第四纪地层北东部出现沉积间断,并且局部地区出现差异沉降,北东侧地势高于南西侧。
Xinxiang is located between the mountainous region of northwest Henan and the plain of east Henan.Both the evolution of Yellow River alluvial fan and the Neotectonic movement have significant effect on the sedimentary process of the study area in Quaternary. This research dated core samples＇ age and compared sedimentary facies of the stratigraphy in the study area according to the description of the core. The result implies that both the evolution of the Yellow River alluvial fan and the movement of the river channel from north to south play an important role in the sedimentation of the study area in Quaternary. Fluvial facies are the main sedimentary facies in this area. And all the drillholes reveal that the thickness of Holocene series is 10 m with the average age of about 9. 5 ka,and the thickness of the Upper Pleistocene series is 69 m with the average age of 129 ka,and the thickness of the Middle Pleistocene series is 55 m with the average age less than 829 ka. This study didn＇t find the bottom interface of the Lower Pleistocene series. In Early Quaternary,the Yellow River alluvial fan located at the west of the study area,and the river channel＇s evolution had little effect on Xinxiang. The main sediments were of fine grained flood plain. As with the movement of the Yellow River from southwest to northeast,the main sediments were of the fluvial facies,and the sand became more than ever. In the Late Qua-ternary,the river channel moved to the south,thus the Yellow River alluvial fan had less impact on the study area than in the middle period of Quaternary,and the sand content decreased. In addition,this research suggests that the hiatus of the northeast of the study area and the differential subsidence in some region are the result of the Neotectonic movement in Early Quaternary. And the terrain in the northeast of the study area is higher than that in the southwest.
出处
《现代地质》
CAS
CSCD
北大核心
2017年第1期81-91,共11页
Geoscience
基金
河南省地震局"新乡市活断层探测与地震危险性评价"项目(HP-2011-502-5)
关键词
第四纪
地层划分
沉积相
沉积环境
河南新乡
Quaternary
stratigraphic subdivision
sedimentary facies
sedimentary environment
Xinxiang of Henan Province
