永定河冲积平原南部第四纪年代地层划分及沉积速率特征

Quaternary chronostratigraphic division and sedimentary rate characteristics in the south alluvial plain of Yongding River

依据磁性地层和^(14)C年代结果,结合岩性分层特征,对永定河冲积平原南部QYJ01年代地层进行划分,并综合QGJ01和QHJ01钻孔年代地层划分成果讨论沉积速率特征。将QYJ01钻孔的年代地层划分为上新统、下更新统、中更新统、上更新统和全新统,其对应孔深分别为198.1~450.9 m、111.5~198.1 m、88.65~111.5 m、23.7~88.65 m和0~23.7 m。综合分析永定河冲积平原南部第四纪代表钻孔QYJ01、QGJ01和QHJ01的沉积速率特征,发现永定河冲积平原南部晚新生代地层沉积中心经历了2次偏移,第1次是始于早更新世、在中更新世完成的沉积中心由中东部向南部偏移,第2次是在全新世完成的沉积中心由南部向中东部回迁。研究结果为永定河冲积平原区新构造运动的活动强度和时限研究及深覆盖区第四纪地层对比提供参考。

Based on magnetostratigraphy and ^(14)C dating,combined with stratification characteristics of strata,the stratigraphy of Quaternary in the southern alluvial plain of Yongding River was classified,and its sedimentary rate was discussed based on the stratigraphic classification results from boreholes QGJ01 and QHJ01.The chronostratigraphy of borehole QYJ01 is divided into Upper Pliocene,Lower Pleistocene,Middle Pleistocene,Upper Pleistocene and Holocene,the corresponding depth is 198.1~450.9 m,111.5~198.1 m,88.65~111.5 m,23.7~88.65 m and 0~23.7 m,respectively.The sedimentary rate of Quaternary strata revealed by boreholes QYJ01,QGJ01 and QHJ01 were analyzed comprehensively.It is indicated that the sedimentary center of the late Cenozoic in the south alluvial plain of Yongding River experienced two migrations:the first was the migration of the sedimentary center from the east to the south in the Early Pleistocene and the second was the migration from the south to the east in the Holocene.This study provides some reference for the study of neotectonic activity intensity and time limit in Yoagding River alluvial plain and the division and correlation of Quaternary stratigraphy in deep covered area.