雄安新区西部GB014孔第四纪地层结构与演化过程  

Quaternary stratigraphic architecture and sedimentary evolution from borehole GB014 in the western Xiong’an New Area

作　　者：刘开明 胥勤勉 段连峰[2] 牛文超 滕飞[2] 王小丹 张伟 董杰[1] Kaiming Liu;Qinmian Xu;Lianfeng Duan;Wenchao Niu;Fei Teng;Xiaodan Wang;Wei Zhang;Jie Dong(School of Environment and Planning,Liaocheng University,Liaocheng 252000,China;Tianjin Center,China Geological Survey,Tianjin 300170,China;School of Tourism,Taishan University,Tai’an 271000,China)

机构地区：[1]聊城大学环境与规划学院,聊城252000 [2]中国地质调查局天津地质调查中心,天津300170 [3]泰山学院旅游学院,泰安271000

出　　处：《科学通报》2020年第20期2145-2160,共16页Chinese Science Bulletin

基　　金：中国地质调查项目(DD20190035);国家自然科学基金(41877442)资助。

摘　　要：对雄安新区西部GB014孔进行了岩石磁学、古地磁和沉积学研究,建立了第四纪地层结构,为更科学利用地下空间提供基础地质支撑.岩石磁学和系统退磁实验揭示钻孔沉积物的载磁矿物主要为磁铁矿,其次为赤铁矿.依据古地磁和区域沉积特征,建立了GB014孔的磁性地层年代框架,下-中更新统界线(M/B界线)和第四系底界(G/M界线)埋深分别为33.8、135.0 m.依据沉积物岩性、结构,以及自然伽玛曲线、粒度、色度、环境磁学参数等将GB014孔划分为5个沉积体系,自下而上依次为:沉积体系Ⅴ为粗颗粒的冲积扇相,埋深为200~146.6 m,年龄为3.90~2.81 Ma,沉积速率为4.9 cm/ka;沉积体系Ⅳ为细颗粒的泛滥平原相,埋深为146.6~108.0 m,年龄为2.81~1.88Ma,沉积速率为2.76 cm/ka;沉积体系Ⅲ为粗颗粒的辫状河道相,埋深为108.0~57.6 m,年龄为1.88~1.02 Ma,沉积速率为5.86 cm/ka;沉积体系Ⅱ为细颗粒的泛滥平原相,埋深为57.6~35.8 m,年龄为1.02~0.79 Ma,沉积速率为9.48 cm/ka;沉积体系Ⅰ为夹决口扇的泛滥平原相,埋深为35.8~0 m,年龄为0~0.79 Ma,沉积速率为4.53 cm/ka.晚上新世以来GB014孔记录了3.90~2.81和1.88~0.79 Ma两次构造活跃期,其中1.88~1.02 Ma时期可能发生物源变化.太行山山前普遍存在这两期构造活动形成的粗颗粒沉积物,而中、晚更新世的砂层则可能与海侵进入渤海湾、区域降水增多有关.To scientifically utilize underground space and to explore the regional structural characteristics and processes of basin evolution of the North China Plain,we combine paleomagnetic and sedimentary analyses of sediments from borehole GB014,which extends 200 m deep,in the western Xiong’an New Area.Magnetostratigraphy and regional sedimentary characteristics were determined to establish a chronological framework.Sedimentary facies and sedimentary systems were reconstructed by considering the lithology,geophysical logs gamma ray(GR),and grain size,sediment color(L*,a*and b*)and magnetic susceptibility measurements.To determine the remanence carriers and magnetic mineralogy of the sediments,rock magnetic measurements were performed on 8 representative samples from various depths.A total of 145 specimens were subjected to progressive thermal demagnetization up to a maximum temperature of 690℃,with intervals of 25-50℃below 585℃and 10-25℃above 585℃,using a Magnetic Measurements Thermal Demagnetizer(TD48)with a residual magnetic field less than 10 nT.Paleomagnetic measurements were made using a 2G Enterprises Model 760-R cryogenic magnetometer installed in a magnetically shielded space(<300 nT)in the Paleomagnetism and Geochronology Laboratory of the Institute of Geology and Geophysics,Chinese Academy of Sciences.GR logs obtained at 20-cm intervals were used to analyze the sedimentary facies.For measurements of sediment color,526 powder samples were air-dried and then disaggregated,passed through a200-mesh sieve and measured using a Konica-Minolta SPAD503 spectrometer.The 526 powder samples were packed into 8-cm3 plastic boxes and used to obtain measurements of magnetic susceptibility(χ)using a Bartington Instruments MS2B sensor.Electronic scales with a resolution of 0.001 g were used to weigh the samples to enable the mass-specific susceptibility to be calculated.For grain-size measurements,189 powder samples were pretreated with 10%H2O2 to remove organic matter and 10%HCl to remove carbonates.After standin

关 键 词：雄安新区 第四纪 磁性地层 地层结构 

分 类 号：P534.63[天文地球—第四纪地质学] P542[天文地球—古生物学与地层学]