河北三河晚更新世地层粒度特征分析  

Grain Size Analysis of the Late Pleistocene Sediments in Sanhe County,Hebei Province

作　　者：刘智荣[1] 沈军[1] 黄静宜[1] 陈耀飞[2] 

机构地区：[1]防灾科技学院地震科学系,河北燕郊065201 [2]中国地质大学(北京)地球科学与资源学院,北京100083

出　　处：《地质学报》2016年第5期997-1005,共9页Acta Geologica Sinica

基　　金：自然科学基金面上项目(41372216);中央高校创新项目团队资助计划(ZY20120102)共同资助

摘　　要：本文通过详细测量河北三河齐心庄一带第四纪剖面、采集光释光测年样品和粒度样品,分析该区地层形成年龄、沉积速率、各粒度样品粒度参数、频率分布曲线及概率累积曲线,进而推断其沉积环境。实测剖面显示地层可以分为20层,沉积物以细砂、粉砂和黏土为主。第2层光释光地质年龄为12.23±1.32ka,第19层光释光地质年龄为19.35±2.10ka,故实测剖面为晚更新世末期堆积,根据地层厚度及年龄测定结果测算出该区平均沉积速率为0.071cm/a。12个粒度样品频率分布曲线均为不对称的单峰态,表明沉积物成分单一,为相对稳定条件下形成。概率累积曲线分为两段式和三段式,滚动组分较少,总体为能量相对不高的沉积环境。地层自下而上呈现明显的旋回性沉积特征,存在两种韵律沉积模式:"中砂-细砂-粉砂"和"粉砂-黏土"。结合区域地质特征,综合分析结果显示河北三河晚更新世地层形成于相对稳定的低水能条件下的河流环境,进一步可细分为河流砂坝和泛滥平原沉积。本文研究结果对于探讨华北北部平原的形成与发展过程、潮白河下游的变迁历史、晚更新世末期的沉积速率提供了重要的基础资料和数据。实测剖面位于新夏垫断裂的下盘,本文测试结果对于研究新夏垫活断裂两盘的差异性活动和断裂性质提供了重要的资料。Measurement,OSL dating and grain size analysis for the Quaternary section in the Qixinzhuang area,Sanhe County,Hebei province,were carried out to better understand the deposition environment of this area.The results show that the section can be divided into 20 layers and the sediments are dominated by fine sand,silt and clay.OSL dating shows that the geological ages is 2.23±1.32 ka for the 2^（th） layer and 19.35±2.10 ka for the 19 thlayer,suggesting that the measured stratigraphic section be accumulated at the end of late Pleistocene.On the basis of the thickness and measured ages,the average deposition rate of the area is 0.071cm/a.Frequency distribution curves of 12 samples show asymmetric single kurtosis,which indicates that the composition of sediments is simple and formed in a relatively stable condition.The probability accumulation curves can be divided into two stages and three stages and the rolling components are less,showing a relatively low energy sedimentary environment.The strata display obvious cyclic sedimentary features from bottom to top.And two kinds of cyclic model have identified： ＂ middle sand-fine sand-silt＂ and ＂ silt-clay＂.Combined with the regional geological features,comprehensive analyses indicate that late Pleistocene strata in Sanhe,Hebei,were developed in a relatively stable river environment with low energy,and can be further subdivided into river sand dam and flood plain deposit.The results of this study provide important basic data for research of the formation and development of North China Plain,the change history of Chaobai River downstream,sedimentation rate during the late Pleistocene.Measured section is located in the bottom wall of the Xinxiadian fault,and this study also has important significance for studying the difference activity of two planes and fracture property.

关 键 词：粒度参数 概率累积曲线 晚更新世 河流砂坝 泛滥平原 

分 类 号：P534.631[天文地球—第四纪地质学]