武汉地区第四纪磁性地层

引用本文

张玉芬, 李长安, 杨伟, 赵举兴, 郁军, 熊智秋. 武汉地区第四纪磁性地层[J]. 地震地质, 2019,41(2): 467-480.
ZHANG Yu-fen, LI Chang-an, YANG Wei, ZHAO Ju-xing, YU Jun, XIONG Zhi-qiu. STUDY ON QUATERNARY MAGNETIC STRATIGRAPHY IN WUHAN AREA, CHINA[J]. SEISMOLOGY AND GEOLOGY, 2019,41(2): 467-480. 复制到剪切板

DOI:10.3969/j.issn.0253-4967.2019.02.013
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武汉地区第四纪磁性地层

张玉芬¹, 李长安^2,³, 杨伟¹, 赵举兴², 郁军², 熊智秋¹

1)中国地质大学(武汉)地球物理与空间信息学院, 武汉 430074

2)中国地质大学(武汉)地球科学学院, 武汉 430074

3)生物地质与环境地质国家重点实验室, 武汉 430074

〔作者简介〕张玉芬, 女, 1957年生, 2000年于中国地质大学(武汉)获地球探测与信息技术专业博士学位, 教授, 博士生导师, 现主要研究方向为环境地球物理与环境地质, 电话: 18602744806, E-mail: zhyfcug@163.com。

收稿日期: 2019-01-02

基金项目: 国家自然科学基金(41672355, 41877292)和武汉市多要素城市地质调查示范项目(WHDYS-2018-004, DD20160250)共同资助

摘要

武汉地区90%为第四系所覆盖, 但目前针对第四纪年代地层的研究严重滞后。文中在武汉市城市地质调查施工的数百个钻孔中选择了地层发育齐全、适于进行磁性地层研究的SK2钻孔进行了古地磁极性测试和分析, 并重点对SK2钻孔进行了磁性地层的划分, 初步建立了武汉市第四纪磁性地层的年代序列。结果表明, SK2钻孔的布容与松山(B/M)界线位于孔深约29.6m处, 其古地磁年龄约0.78Ma; 松山反向带中的正极性亚时贾拉米洛(Jaramillo)、奥杜威(Olduvai)、留尼汪(Reunion)Ⅱ分别位于孔深38.2~39.8m、 66.5~71.9m和75.8~78.4m处。依据磁性地层结果对研究钻孔进行了第四纪地层划分, SK2钻孔的1.2~14.1m为上更新统, 15~29.6m为中更新统, 29.6~78.8m为下更新统。计算SK2钻孔地层的沉积速率后发现, 古地磁年代1.47~1.57Ma BP和1.07~1.21Ma BP为2个沉积速率相对增大的阶段。

关键词: SK2钻孔; 第四系; 磁性地层; 武汉地区

中图分类号:P318.4 文献标志码:A 文章编号:0253-4967(2019)02-0467-14

STUDY ON QUATERNARY MAGNETIC STRATIGRAPHY IN WUHAN AREA, CHINA

ZHANG Yu-fen¹, LI Chang-an^2,³, YANG Wei¹, ZHAO Ju-xing², YU Jun², XIONG Zhi-qiu¹

1)Institute of Geophysics and Geomatics, China University of Geosciences, Wuhan 430074, China

2)Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, China

3)State Key Laboratory of Biogeology and Environmental Geology, Wuhan 430074, China

Abstract

With the lateral and vertical expansion of cities, urban geology becomes critical for urban construction. Wuhan City, as one of the largest cities in China, was chosen by China Geological Survey as pilot city to study multiple elements of urban geological survey. 90% of Wuhan area is covered by Quaternary strata, which means that most of the city is built on Quaternary sediments. The study of Quaternary stratigraphic structure of Wuhan area is a crucial groundwork for the urban geological survey of Wuhan. Due to the badly lagging of research on Quaternary stratigraphy of Wuhan area, this study selects four boreholes from hundreds of cores in this area in the project of Wuhan Urban Geological Survey for magnetic stratigraphic study and paleomagnetic analysis. This work mainly focuses on the borehole SK2 which possesses well-developed strata and is representative for magnetic strata division. Wuhan is located in the eastern Jianghan Basin where the Quaternary sediment has a fluctuant bottom edge, forming a half-graben shape boundary in large scale, as revealed by a large amount of boreholes. The borehole SK2 is located in the western Dongxi Lake depression. SK2 reveals continuous deep Quaternary sediment except for a short gap of late Pleistocen-early Holcene. Moreover, the grain size of drill core is generally smaller than other cores nearby, which is more suitable for paleomagnetic study.

In this study, we collected 117 samples with an interval of 0.25~0.30m from relative fine grain layers in the borehole for paleomagnetic study. Demagnetization and sample measurement were conducted in State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, CAS. By comparing with other well dated cores nearby, Wuhan's Quaternary magnetic stratigraphic chronology framework is initially established. Our data show that: 1)the Brunhes-Matsuyama boundary(B/M)of borehole SK2 is clear, locating at 29.6m, and sediment at 1.2~29.6m belongs to Bmnhes normal polarity chron; 2)Two polarity drifts at 9.3~9.6m and 14.1~15.0m are observed in Brunhes. These samples collected from the Xiashu Loess yield two polarity drifts, which can be compared with the Xiashu Loess at Nanjing. The comparison between Xiashu Loess from borehole SK2 and that at Nanjing suggests that negative polarity drift at 14.1~15.0m is the Blake reverse polarity subchron(0.104~0.128Ma BP)and the polarity drifts at 9.3~9.6m(0.07~0.08Ma BP)is Norwegian-Greenland Sea reversal-polarity subchron; 3)Three polarity drifts were observed in Matsuyama, which is comparable with the borehole at Zhoulao and the borehole R25 in the center of the Jianghan Basin. They are at 38.2~39.8m(Jaramillo: 0.99~1.07Ma BP), 66.5~71.9m(Olduvai: 1.77~1.95Ma BP)and 75.8m(Reunion: 2.01Ma BP); 4)Based on the forementioned paleomagnetic data, the depositional age structure of this borehole is: 1.2~14.1m(late Pleistocene), 15~29.6m(middle Pleistocene)and 29.6~78.8m(early Pleistocene); 5)Our data show that deposition rate increased during 1.47~1.57Ma BP(54.9~61.3m)and 1.07~1.21Ma BP(39.8~47.3m)because they are fluvial sediments. This study builds the Quaternary stratigraphy and timescale for Wuhan area for the first time. However, because of the complex Quaternary sediment type in Wuhan area and the coarse sediment in the Matuyama, more comprehensive study is needed in the future to test whether our Quaternary stratigraphy and timescale is the best.

Keyword: borehole SK2; Quaternary; magnetic stratigraphy; Wuhan area

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0 引言

近代以来, 武汉一直是具有国家战略意义的重要中心城市。当前, 武汉面临多重国家战略机遇, “ 一带一路” 倡议、建设长江经济带、 “ 中部崛起” 等国家重大战略聚焦武汉。作为国家中心城市、长江经济带超大城市等, 武汉在中国中部地区具有重要地位。近年来, 随着城市的建设, 特别是地下空间利用的快速发展, 城市地质问题不断出现, 城市地质调查引起了高度关注, 中国地质调查局将武汉列为 “ 多要素城市地质调查试点城市” 。武汉市近地表90%为第四系所覆盖(邓健如等, 1991), 即武汉市城市建设的主要承载地质体为第四系。因此, 第四纪地层研究已成为武汉市多要素城市地质工作中的一个非常重要的基础性工作。前人对武汉地区的第四纪地层(陈华慧等, 1987; 关康年等, 1990; 黄宁生等, 1993; 柏道远等, 2010; 田望学等, 2011)及年代学(康悦林, 1987; 杨勇等, 2008)等曾做过一些研究, 也取得了一定进展。但其中大部分为针对出露有限的地表露头的研究, 虽有钻孔研究, 也仅针对第四纪晚期的某一时段(林晓等, 2011; 霍炬, 2015), 已有研究结果无法满足多要素城市地质调查的需要。选择地层发育齐全的钻孔开展系统的地层序列研究, 特别是建立地层年代框架, 已成为当前三维城市地质和区域地壳稳定性评价工作的当务之急。

磁性地层学是当前建立第四纪年代地层框架的重要手段(Deng et al., 2019), 特别是在解决第四纪长时间尺度地层序列的时代划分和对比方面卓有成效。磁性地层年代学方法已经成为平原和盆地地区第四纪地层序列和年代框架研究的有效方法(安芷生等, 1979; 刘进峰等, 2005; 乔彦松等, 2006; 陈杰等, 2007; 王喜生等, 2007; 朱日祥等, 2007; 陈宇坤等, 2008; 肖国桥等, 2008; 张磊等, 2017)。本研究从近年来开展的武汉市城市地质调查一期施工的数百个钻孔中^①(① 张玉芬等, 2015, “ 武汉城市地质调查第四纪地质专题调查与研究” 报告, 中国地质大学(武汉)｡), 选择第四系厚度大、地层发育具有代表性、沉积连续性好、粒度相对较细的SK2孔进行了磁性地层的划分, 首次建立了武汉地区第四纪磁性地层年代框架, 为武汉市多要素城市地质调查, 特别是地下空间利用研究提供了基础资料。

1 研究钻孔的第四纪岩性特征

SK2孔位于武汉东西湖区柏泉街的冲积平原地貌区(图1), 通过与区内万余个钻孔进行比较后发现, 该钻孔厚度较大(超过以往研究得到的武汉市第四系厚度56m的认识), 沉积连续, 未发现明显的沉积间断; 地层发育齐全, 且细粒沉积层较多, 是目前在武汉地区开展第四纪磁性地层研究最理想的钻孔。依据岩心沉积物的岩性特征及其变化情况划分出39个岩性层, 为便于研究, 将其合并成4个岩性段, 自下而上各段岩性特征描述如下:

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	图 1 研究区地貌分区及研究钻孔分布位置图Fig. 1 The geomorphic division of the study area and the location of the boreholes.

第一岩性段: 孔深78.8~46.0m, 沉积物以深褐色、青灰色和深灰色为主, 岩性主要以粉砂、细砂、中砂、砾石为主。中间夹有炭化木层, 纹路清晰。总体上构成了2个砂砾-粉砂黏土层互层的旋回沉积结构, 属河流与湖沼相交互沉积, 厚32.8m。

第二岩性段: 孔深46.0~21.3m, 沉积物以青灰色、灰绿色、深灰色为主, 岩性较为复杂, 主要为粉砂、细砂、中砂、粗砂、砾石, 正粒序特征比较明显, 总体上构成砂砾-粉砂的沉积序列, 属于平原河流相沉积, 厚24.7m。

第三岩性段: 孔深21.3~17.6m, 岩性主要为褐红色黏土, 夹有浅灰色、灰白色高岭土条带, 偶见铁锰结核。属洪泛平原相沉积, 厚3.7m。

第四岩性段: 孔深17.6~0m, 岩性主要为褐黄色、黄褐色黏土, 岩性和质地均一, 含铁锰结核, 发育有铁锰质氧化物胶膜。总体属于风积成因, 厚17.6m。

2 样品的采集与测试

2.1 样品采集

结合区域地质资料和钻孔岩性变化特征, 以0.25~0.3m为间距进行了古地磁样品的采集。采样的基本原则是: 在钻孔岩心较完整、连续、粒度较细的层位选择取样, 尽量避开粗砂和砾石层。进行采样时, 首先将钻机提取的岩心固定在PVC管中, 清除包裹的泥浆, 再用不锈钢刀将岩心破开, 并使平面与岩心轴平行; 然后取一个标有方向线的无磁圆柱形塑料盒(直径2.5cm, 高2.2cm)作为样品盒, 使其方向线与岩心的深度方向在同一直线上, 均匀用力垂直按下, 直至岩心充满整个塑料盒, 并在野簿上记录古地磁样品的编号和取样深度; 最后把样品取出, 写明样品编号, 用保鲜膜密封以防止失水造成沉积物松动, 并置放于不受强磁场干扰的容器中。本研究在SK2钻孔中共采集样品177个。

2.2 样品测试

样品退磁和测试在中国科学院地球环境研究所(西安)黄土与第四纪地质国家重点实验室完成。古地磁实验在磁屏蔽室内(磁场强度< 300nT, 绝大部分空间< 100nT)进行, 其屏蔽材料可排除地磁场对实验仪器和所测样品的干扰, 以便获得可靠的实验结果。

首先用美国2G公司生产的2G-755R交变退磁仪对样品进行交变退磁处理, 测量剩磁退磁强度分别为0mT、 20mT、 50mT、 75mT、 100mT、 150mT、 200mT、 250mT、 300mT、 350mT、 400mT、 450mT、 500mT、 600mT、 700mT和800mT, 然后再使用2G-755R U-channel超导磁力仪测量样品的剩磁。超导磁力仪的测量范围是2.0× 10^-12~2.0× 10^-4Am², 灵敏度为2.0× 10^-12Am²。

3 实验结果及分析

本文使用Craig H J和Joya T编写的PaleoMag软件对退磁数据的正交投影图进行主成分分析, 得到每个样品各个退磁段的剩磁组分数据。通过最小二乘拟合法确定出剩磁组分数据新的坐标轴(Kirschvink, 1980; 金国海等, 1992; 黄宝春等, 1994), 并采用最大角偏差(MAD: The biggest angle deviation mad)判断一组数据是共线还是共面, 当其小于给定的MAD临界值(本文取15° )时认为其共线, 表示拟合较好, 结果可靠。由此得到每个样品逐步退磁的几何结构。其中, 通过原点的那条(段)退磁直线的方向就代表最稳定的剩磁组分方向, 其它退磁直线的方向则为稳定性较差的磁性组分方向; 当MAD超过临界值时, 表示拟合不佳, 退磁结果不可取。下面对SK2孔的实验结果进行分析与讨论。

通过对SK2钻孔的177个样品进行交变退磁处理, 获得了相应的交变退磁数据, 图 2为代表性样品的退磁正交投影图和剩余磁化强度衰减图。分析图 2可知SK2孔样品的退磁曲线具有如下几个特点: 1)大多数样品的退磁曲线为1条稳定下降的直线, 且指向原点, 表示只有1种磁组分被清洗掉(图2a, b), 且剩磁强度衰减曲线在0~150mT发生了快速下降, 又在200mT以后趋于平缓(图2 i, j), 此类样品能够获得稳定的特征剩磁方向。2)部分样品(如图2c— h所代表的样品)的退磁曲线具有大致相同的特点, 这些样品在150mT有明显的变化, 均显示出2个分量(图2c, h)。其中一部分样品的第一分量与现代地磁场方向一致(图2c, d, g, h), 而另一部分样品的第一分量与现代地磁场方向却相反(图2e, f)。第一分量代表次生粘滞剩磁, 一般在150mT前就可以被清洗掉。第二分量代表原生特征剩磁的方向, 在150~400mT内可获得稳定的特征剩磁的方向。3)少部分样品在0~150mT也表现出与现代地磁场方向一致的次生粘滞剩磁, 但在150mT后的退磁曲线并不趋向原点, 因此也未能获得代表当时地磁场方向的特征剩磁, 在进行数据分析时应当剔除。4)极少样品未能分离出特征剩磁, 在退磁过程中其剩磁方向极不稳定, 也应予以剔除。

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图 2 SK2钻孔代表性样品交变退磁正交投影图和剩余磁化强度衰减图
a、i 1号样品, 深1.2m; b、j 7号样品, 深3.73m; c、k 10号样品, 深4.83m; d、l 24号样品, 深11.10m; e、m 46号样品, 深16.23m; f、n 48号样品, 深16.6m; g、p 50号样品, 深17.05m; h、q 84号样品, 深27.04mFig. 2 Orthogonal projection of alternating demagnetization and residual magnetization attenuation of the representative samples from borehole SK2.

总之, 大部分(> 70%)样品经过交变退磁处理后, 能获得代表当时地磁场方向的特征剩磁。从被剔除的样品比例和其在岩心中的分布来看, 被剔除的样品并不集中, 故根据解释数据中的磁倾角建立SK2孔的磁极性柱结果是可靠的。

4 武汉市磁性地层年代序列的建立

4.1 SK2钻孔磁性地层年代框架

图 3为基于得到的稳定特征剩磁样品的磁倾角数据建立的SK2钻孔磁极性柱与标准极性柱(Cande et al., 1995)的对比图。结果表明, SK2钻孔布容与松山(B/M)的界限位于29.6m深处, 其中1.2~29.6m深度范围内为布容正向极性时, 29.6~78.8m深度范围内为松山反向极性时。

在布容期(Brunhes)内存在2次负极性漂移事件, 分别位于深9.3~9.6m和14.1~15.0m处。从钻孔岩性变化上看, 1.0~17.6m深度范围内以褐黄色黏土为主, 铁锰质含量十分丰富, 而17.6~21.2m为褐红色黏土, 偶见铁锰结核。前者为上更新统下蜀组( $Q_{p}^{3 x}$ ), 后者为中更新统辛安渡组( $Q_{p}^{2 x}$ )。经与标准磁极性年表进行对比, 将深9.3~9.6m处的负极性漂移事件定为挪威-格陵兰海(Norwegian-Greenland Sea)负极性亚时, 对应的地质年龄为0.07~0.08Ma。深14.1~15.0m处的负极性漂移事件定为布莱克(Blake)负极性亚时, 地质年龄为0.104~0.128Ma。

在松山期(Matuyama)内存在多次正极性漂移事件, 经与标准磁极性年表进行对比, 初步认为: 深度为38.2~39.8m的极性漂移事件为贾拉米洛(Jaramillo)正极性亚时, 地质年龄为0.99~1.07Ma; 深度为66.5~71.9m的极性漂移事件为奥杜威(Olduvai)正极性亚时, 地质年龄为1.77~1.95Ma; 深75.8m处的极性转换对应留尼汪(Reunion)Ⅱ 的上界, 地质年龄为2.01Ma, 钻孔底部仍位于留尼汪(Reunion)Ⅱ 内。另外, 在SK2钻孔中还发现位于孔深47.3~48.9m处的科布山(Cobb Mountain)正极性亚时, 地质年龄为1.20~1.21Ma; 在孔深54.4~54.9m处存在加德尔(Gardar)正极性事件, 地质年龄为1.47~1.48Ma; 孔深1.3~62.5m处存在吉尔萨(Gilsa)正极性事件, 地质年龄为1.57Ma。

4.2 武汉地区第四纪地层的沉积速率

古地磁年表的建立不仅可以为地层划分对比提供年代学依据, 而且可以反映出不同地质时期沉积厚度和沉积速率的变化, 从而为研究第四纪古地理的环境变化提供依据(范代读等, 1998)。

根据SK2孔地磁极性带的解释和界线年龄, 计算出各孔的沉积速率变化情况。具体做法为: 设相邻2个年龄控制点的埋深分别为为H₁ 和H₂, 年龄分别为T₁ 和T₂, 则2个年龄控制点之间的沉积厚度为H₂-H₁, 年代间距为T₂-T₁, 通过 $R_{T_{2} T_{1}} = (H_{2} - H_{1}) / (T_{2} - T_{1})$ 计算得到T₂ 到T₁ 的平均沉积速率 $R_{T_{2} T_{1}}$ , 然后可以利用线性方程求得这2个年龄控制点埋深之间任意点的年龄(许炯心, 2007)。按照这种做法进行外推, 绘出了SK2钻孔的深度-年龄曲线(图4)。

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	图 4 SK2钻孔深度-年龄及沉积速率曲线Fig. 4 Depth-age and deposition rate curve of borehole SK2.

从图 4中可以看出, SK2钻孔存在沉积速率明显增大的2个阶段: 阶段一位于孔深39.8~47.3m(年龄1.07~1.2Ma); 阶段二位于孔深54.9~61.3m(年龄1.48~1.57Ma)。从岩性上看, 阶段一下部为中砂夹砾石, 砾石磨圆分选差, 中部存在近4.0m厚的砾石层, 砾石磨圆一般, 次圆, 上部为青灰色粗砂混有砾石, 与深度> 47.3m的深褐色-褐灰色砂质黏土与粉砂互层(发育间隔约2mm的水平纹理)的沉积环境相比已经发生了剧烈变化, 表明水动力条件增强, 物源供给增多。结合前期的研究结果(Zhang et al., 2008)可知, 这可能与长江三峡的贯通有关。阶段二的下部以青色-灰绿色砂质黏土夹粉砂为主, 中部为青灰色中砂, 上部为青灰色粗砂夹砾石, 自下向上粒度逐渐变粗。从钻孔底部到孔深66.0m处, 沉积物岩性依次为青灰色中砂、青灰色黏土、砾石层、青灰色中砂、细砂、炭化木层、青灰色细砂, 为河湖相沉积。这可能与早更新世中期气温回升、降雨量增加(陈华慧等, 1987)导致沉积环境发生明显变化有关。

5 讨论

5.1 关于极性时的确定

极性时(磁性倒转)和极性亚时(漂移事件)的确立是磁性地层定年的前提和基础。一般而言, 地层的岩性、连续性和沉积环境等均会影响极性时和极性亚时的确定, 即通过稳定沉积环境下不存在沉积间断且均一性较好的细粒沉积物可获得较理想的磁性地层定年效果。武汉地区位于江汉平原东缘, 为典型的陆相沉积环境, 这就决定了其磁性地层研究的相对复杂性(Zhang et al., 2008)。SK2孔位于武汉地区西部, 更靠近江汉平原腹地。大量的钻孔揭露武汉地区第四系基底起伏明显, 但总体上为一西深东浅的箕状洼地, SK2孔位于东西湖凹陷内, 钻孔附近的沉积除晚更新世末到全新世早期有一定间断外, 基本上是连续的, 同时, 钻孔所在位置也是东西湖凹陷内沉积物粒度相对较细的区域, 故对极性时和亚时的记录应该是完整的。对于极性时和亚时划定的可靠性, 尽管本次研究没有对岩心进行¹⁴C、 OSL、 ESR等绝对年代测定, 但仍可通过与已有的研究进行对比检验。SK2孔第三岩性段为武汉地区岩石地层中的辛安渡组(或王家店组), 其岩性特征为长江中下游广泛分布的网纹红土。网纹红土是长江中下游以南地区非常典型的第四纪土状堆积物, 前人的研究表明, 其古地磁年代属于布容极性时(蒋复初等, 1997; 李长安等, 1997; Qiao et al., 2003), 绝对年龄测定结果显示其主体形成于0.73~0.10MaiBP(杨浩等, 1996; 袁宝印等, 2008)。基于上述分析可知, 将B/M界限定在29.6m处是可行的。

5.2 关于极性亚时的确定

布容期(Brunhes)的布莱克(Blake)负极性亚时位SK2孔深14.1~15.0m处。钻孔岩性(图3)显示自孔深17.6m向上岩性逐渐变为黄褐色沙质黏土, 同时铁锰结核和铁锰薄膜开始发育, 与区域岩性地层进行对比后认为其应属长江中下游广泛发育的下蜀黄土。据下蜀黄土的典型沉积地区— — 南京泰山新村剖面和燕子矶剖面的古地磁年代测定结果(武春林等, 2006)可知, 布莱克(Blake)亚时位于剖面中下部, 与本钻孔布莱克(Blake)亚时出现的层位大致相当。

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	图 3 SK2钻孔极性柱与标准极性柱对比Fig. 3 Comparison of geomagnetic polar column of borehole SK2 with standard polar column.

松山期(Matuyama)亚时内有多个极性漂移事件(亚时), 其特征与江汉盆地的代表性钻孔— — 周老孔(Zhang et al., 2008)和R25孔(张景鑫, 1995)相似, 难以与标准极性柱准确地一一对应, 这可能与江汉盆地第四纪沉积粒度较粗有关。本文参考前人研究, 将极性亚时的特征(极性漂移持续时间等)与标准极性柱进行了对比, 其准确性有待测年研究进一步证实。

6 结论

通过对武汉地区第四系代表性钻孔的岩心进行古地磁测试与极性分析, 初步建立了武汉地区第四纪地层序列和磁性地层年代框架, 获得的主要结论如下:

(1)SK2钻孔的样品的交变退磁处理结果表明, 约70%的样品经过交变退磁处理后可获得代表当时地磁场方向的特征剩磁, 并且一般能将样品的剩余磁化强度退至初始值的10%以下。

(2)SK2钻孔古地磁揭露的布容与松山(B/M)界线位于孔深29.6m处, 贾拉米洛(Jaramillo)正极性亚时位于38.2~39.8m处, 地层年龄为0.99~1.07Ma。奥杜威(Olduvai)正极性亚时位于孔深66.5~71.9m处, 地层年龄相当于1.77~1.95Ma。钻孔75.8m至孔底部对应留尼汪(Reunion)Ⅱ , 对应的年龄为2.01~2.04Ma, 但未出现松山与高斯(M/G)界线。

(3)由SK2钻孔的古地磁年代可将武汉市平原区第四纪地层划分为上更新统(孔深1.2~14.1m)、中更新统(孔深15.0~29.6m)和下更新统(孔深29.6~78.8m), 下更新统底部的年龄约2.02Ma, 缺失早更新世早期沉积物。

(4)SK2钻孔的地层沉积速率表明, 在早更新世时期该区域的沉积速率均有2个相对增大的阶段, 古地磁年龄分别为1.47~1.57Ma和1.07~1.21Ma。这与前期得到的江汉平原钻孔的研究结果具有较好的一致性(Zhang et al., 2008)。

本文首次较系统地建立了武汉地区第四纪磁性地层年代框架, 弥补了武汉地区第四纪年代地层研究的不足, 为区域地层的划分和对比研究提供了参考数据。但由于武汉地区第四纪沉积物类型较复杂, 特别是早更新世地层粒度较粗, 所建立的磁性地层年代序列是否合理还有待进一步的验证和完善。

致谢研究生杨明明、常国瑞、江华军等参加了野外古地磁样品的采集; 中国科学院地球环境研究所黄土与第四纪地质国家重点实验室协助完成了古地磁样品的测试; 审稿专家对论文提出了宝贵的修改意见及建议。在此一并表示感谢!

The authors have declared that no competing interests exist.

参考文献

View Option

1	安芷生, 魏兰英, 卢演俦, 等. 1979. 顺5孔的磁性地层学和早松山世的北京海侵[J]. 地球化学, (4): 343—346. [本文引用:1]
2	AN Zhi-sheng, WEI Lan-ying, LU Yan-chou, et al. 1979. Magnetostratigraphy of the core S-5 and the transgression in the Beijing area during the early Matuyama Epoch[J]. Geochimica, (4): 343—346(in Chinese). [本文引用:1]
3	柏道远, 李长安. 2010. 江汉盆地第四纪地质研究现状[J]. 地质科技情报, 29(6): 1—6. [本文引用:1]
4	BAI Dao-yuan, LI Chang-an. 2010. Status of Quaternary geology research of Jianghan Basin[J]. Geological Science and Technology Information, 29(6): 1—6(in Chinese). [本文引用:1]
5	陈华慧, 马祖陆. 1987. 江汉平原下更新统[J]. 地球科学(武汉地质学院学报), 12(2): 129—135. [本文引用:2]
6	CHEN Hua-hui, MA Zu-lu. 1987. Lower Pleistocene series in Jianghan Plain[J]. Earth Science(Journal of Wuhan College of Geology), 12(2): 129—135(in Chinese). [本文引用:1]
7	陈杰, Heermance R V, Burbank D W, et al. 2007. 中国西南天山西域砾岩的磁性地层年代与地质意义[J]. 第四纪研究, 27(4): 576—578. [本文引用:1]
8	CHEN Jie, Heermance R V, Burbank D W, et al. 2007. Magnetochronology and its implications of the Xiyu conglomerate in the southwestern Chinese Tian Shan foreland [J]. Quaternary Sciences, 27(4): 576—578(in Chinese). [本文引用:1]
9	陈宇坤, 李振海, 邵永新, 等. 2008. 天津地区第四纪年代地层剖面研究[J]. 地震地质, 30(2): 383—398. [本文引用:1]
10	CHEN Yu-kun, LI Zhen-hai, SHAO Yong-xin, et al. 2008. Study on the Quaternary chronostratigraphic section in Tianjin area[J]. Seismology and Geology, 30(2): 383—398(in Chinese). [本文引用:1]
11	邓健如, 伍维周, 秦志能. 1991. 武汉市第四纪地层的划分[J]. 湖北大学学报(自然科学版), 13(2): 178—183. [本文引用:1]
12	DENG Jian-ru, WU Wei-zhou, QIN Zhi-neng. 1991. The division of the Quaternary system of Wuhan[J]. Journal of Hubei University(Natural Science), 13(2): 178—183(in Chinese). [本文引用:1]
13	范代读, 李从先, 陈庆强, 等. 1998. 上海地区晚第四纪磁性地层的初步研究[J]. 海洋地质与第四纪地质, 18(2): 103—106. [本文引用:1]
14	FAN Dai-du, LI Cong-xian, CHEN Qing-qiang, et al. 1998. Late Quaternary magnetic stratigraphy in the south flank of the Yangtze River delta[J]. Marine Geology and Quaternary Geology, 18(2): 103—106(in Chinese). [本文引用:1]
15	关康年, 鄢志武. 1990. 江汉平原北缘的下更新统[J]. 地球科学(中国地质大学学报), 15(5): 481—486. [本文引用:1]
16	GUAN Kang-nian, YAN Zhi-wu. 1990. The lower Pleistocene series on the northern edge of Jianghan Plain[J]. Earth Science(Journal of China University of Geosciences), 15(5): 481—486(in Chinese). [本文引用:1]
17	黄宝春, 谭承泽. 1994. 古地磁多磁成分的分离技术[J]. 地球物理学进展, 9(1): 125—134. [本文引用:1]
18	HUANG Bao-chun, TAN Cheng-ze. 1994. Technology of separating the multi-component magnetization in palaeomagnetism[J]. Progress in Geophysics, 9(1): 125—134(in Chinese). [本文引用:1]
19	黄宁生, 关康年. 1993. 鄂东阳逻地区早更新世砾石层研究[J]. 地球科学(中国地质大学学报), 18(5): 589—597. [本文引用:1]
20	HUANG Ning-sheng, GUAN Kang-nian. 1993. Study on early Pleistocene gravel beds in Yangluo area, east of Hubei Province[J]. Earth Science(Journal of China University of Geosciences), 18(5): 589—597(in Chinese). [本文引用:1]
21	霍炬, 李启文. 2015. 武汉东西湖区ZK02孔沉积物粒度特征及对沉积环境的指示[J]. 资源环境与工程, 29(3): 259—266. [本文引用:1]
22	HUO Ju, LI Qi-wen. 2015. Grain size characteristics and its environmental significance of ZK02 core sediment recorded in Dongxihu district, Wuhan[J]. Resources Environment and Engineering, 29(3): 259—266(in Chinese). [本文引用:1]
23	蒋复初, 吴锡浩, 肖华国, 等. 1997. 九江地区网纹红土的时代[J]. 地质力学学报, 3(4): 27—32. [本文引用:1]
24	JIANG Fu-chu, WU Xi-hao, XIAO Hua-guo et al. 1997. Age of the vermiculated red soil in Jiujiang area, central China[J]. Journal of Geomechanics, 3(4): 27—32(in Chinese). [本文引用:1]
25	金国海, 方大钧, 吴能友. 1992. 多剩磁成分的主成分法分离及其应用[J]. 地球物理学报, 35(5): 621—629. [本文引用:1]
26	JIN Guo-hai, FANG Da-jun, WU Neng-you. 1992. Principal component analysis and its palaeomagnetic application[J]. Chinese Journal of Geophysics, 35(5): 621—629(in Chinese). [本文引用:1]
27	康悦林. 1987. 江汉平原第四纪地层划分与古气候分期[J]. 湖北地质, 1(1): 1—10. [本文引用:1]
28	KANG Yue-lin. 1987. The stratigraphic division and palaeoclimate-divided stage of Quaternary period in Jianghan Plain[J]. Hubei Geology, 1(1): 1—10(in Chinese). [本文引用:1]
29	李长安, 顾延生. 1997. 江西修水第四系网纹红土的地层学研究[J]. 地层学杂志, 21(3): 226—232. [本文引用:1]
30	LI Chang-an, GU Yan-sheng. 1997. Stratigraphic study on the vermiculated red earth at Xiushui County, Jiangxi Province[J]. Journal of Stratigraphy, 21(3): 226—232(in Chinese). [本文引用:1]
31	林晓, 卢佳仪, 田望学, 等. 2011. 武汉东西湖区第四系钻孔的沉积环境及古气候变化[J]. 地质科技情报, 30(3): 33—40. [本文引用:1]
32	LIN Xiao, LU Jia-yi, TIAN Wang-xue, et al. 2011. Sedimentary environment and palaeoclimate changes reflected by Quaternary sediments of the bore ZK25 in Dongxihu district of Wuhan City[J]. Geological Science and Technology Information, 30(3): 33—40(in Chinese). [本文引用:1]
33	刘进峰, 郭正堂, 郝青振, 等. 2005. 甘肃秦安糜子湾剖而中新世风尘堆积的磁性地层学研究[J]. 第四纪研究, 25(4): 503—509. [本文引用:1]
34	LIU Jin-feng, GUO Zheng-tang, HAO Qing-zhen, et al. 2005. Magnetostratigraphy of the Miziwan Miocene eolian deposits in Qin'an County(Gansu Province)[J]. Quaternary Sciences, 25(4): 503—509(in Chinese). [本文引用:1]
35	乔彦松, 赵志中, 王燕, 等. 2006. 川西甘孜黄土磁性地层学研究及其古气候意义[J]. 第四纪研究, 26(2): 250—256. [本文引用:1]
36	QIAO Yan-song, ZHAO Zhi-zhong, WANC Yan, et al. 2006. Magnetostratigraphy and its paleoclimatic significance of a loess-soil sequence from Ganzi area, west Sichuan plateau[J]. Quaternary Sciences, 26(2): 250—256(in Chinese). [本文引用:1]
37	田望学, 毛新武, 何仁亮, 等. 2011. 武汉地区 1: 5万区调第四系研究进展[J]. 华南地质与矿产, 27(4): 286—291. [本文引用:1]
38	TIAN Wang-xue, MAO Xin-wu, HE Ren-liang, et al. 2011. Progresses in Quaternary system of Wuhan area in 1: 50 000 regional geological survey[J]. Geology and Mineral Resources of South China, 27(4): 286—291(in Chinese). [本文引用:1]
39	武春林, 朱诚, 鹿化煜, 等. 2006. 南京地区下蜀黄土磁性地层年代与古环境变化[J]. 地层学杂志, 30(2): 116—123. [本文引用:1]
40	WU Chun-lin, ZHU Cheng, LU Hua-yu, et al. 2006. Magnetostratigraphical dating of the Xiashu loess in Nanjing area and its paleoenvironmental interpretation[J]. Journal of stratigraphy, 30(2): 116—123(in Chinese). [本文引用:1]
41	肖国桥, 郭正堂, 陈宇坤, 等. 2008. 渤海湾西岸BZ₁钻孔的磁性地层学研究[J]. 第四纪研究, 28(5): 909—916. [本文引用:1]
42	XIAO Guo-qiao, GUO Zheng-tang, CHEN Yu-kun, et al. 2008. Magneto stratigraphy of BZ₁ borehole in west coast of Bohai Bay, northern China[J]. Quaternary Sciences, 28(5): 909—916(in Chinese). [本文引用:1]
43	王喜生, 杨振宇, Lφvlie R, 等. 2007. 松山—布容地磁极性倒转在黄土高原东南缘记录的可靠性探讨[J]. 第四纪研究, 27(6): 963—971. [本文引用:1]
44	WANC Xi-sheng, YANG Zhen-yu, Lφvlie R, et al. 2007. Discussion on the recording fidelity of the Matuyama/Brunhes boundary in the southeastern extremity of the Chinese loess plateau[J]. Quaternary Sciences, 27(6): 963—971(in Chinese). [本文引用:1]
45	许炯心. 2007. 基于大样本¹⁴C测年资料的华北平原沉积速率研究[J]. 第四纪研究, 27(3): 437—443. [本文引用:1]
46	XU Jiong-xin. 2007. A study of deposition rate in the North China plain during the past 40000 years based on ¹⁴C dating data from a large wealth of samples[J]. Quaternary Sciences, 27(3): 437—443(in Chinese). [本文引用:1]
47	杨浩, 赵其国, 李小平, 等. 1996. 安徽宣城风成沉积红土系列剖面ESR年代学研究[J]. 土壤学报, 33(3): 293—300. [本文引用:1]
48	YANG Hao, ZHAO Qi-guo, LI Xiao-ping, et al. 1996. ESR dating of eolian sediment and red earth series from Xuancheng profile in Anhui Province[J]. Acta Pedologica Sinica, 33(3): 293—300(in Chinese). [本文引用:1]
49	杨勇, 李长安, 胡思辉, 等. 2008. 武汉青山 “砂山”粒度特征及其成因指示[J]. 沉积学报, 26(3): 487—493. [本文引用:1]
50	YANG Yong, LI Chang-an, HU Si-hui, et al. 2008. Grain size features and genesis of the Qingshan “Sand -dune” in Wuhan[J]. Acta Sedimentologica Sinica, 26(3): 487—493(in Chinese). [本文引用:1]
51	袁宝印, 夏正楷, 李保生, 等. 2008. 中国南方红土年代地层学与地层划分问题[J]. 第四纪研究, 28(1): 1—13. [本文引用:1]
52	YUAN Bao-yin, XIA Zheng-kai, LI Bao-sheng, et al. 2008. Chronostratigraphy and stratigraphic division of red soil in southern China[J]. Quaternary Sciences, 28(1): 1—13(in Chinese). [本文引用:1]
53	张景鑫. 1995. 汉平原第四纪磁性地层的划分与探讨 [A]//中国地质学会第四纪冰川与第四纪地质专业委员会编. 第四纪冰川与第四纪地质论文集(第八集), 北京: 地质出版社: 164—174. [本文引用:1]
54	ZHANG Jing-xin. 1995. Quaternary magnetic stratigraphy delimit and discussion on Jianghan Plain [A]//Commission on Quaternary Glaciology and Geology, the Geological Society of China(ed). Collected Papers on Quaternary Glaciology and Quaternary Geology(No. 8). Geological Publishing House, Beijing: 164—174(in Chinese). [本文引用:1]
55	张磊, 白凌燕, 赵勇, 等. 2017. 北京南口-孙河断裂与黄庄-高丽营断裂交会区沉积速率差异对断裂活动性的响应[J]. 地震地质, 39(5): 1048—1065. doi: 10.3969/j.issn.0253-4967.2017.05.013. [本文引用:1]
56	ZHANG Lei, BAI Ling-yan, ZHAO Yong, et al. 2017. The difference of deposition rate in the boreholes at the junction between Nankou-Sunhe Fault and Huangzhuang-Gaoliying Fault and its response to fault activity in the Beijing area[J]. Seismology and Geology, 39(5): 1048—1065(in Chinese). [本文引用:1]
57	朱日祥, 邓成龙, 潘永信. 2007. 泥河湾盆地磁性地层定年与早期人类演化[J]. 第四纪研究, 27(6): 922—944. [本文引用:1]
58	ZHU Ri-xiang, DENG Cheng-long, PAN Yong-xin. 2007. Magnetochronology of the fluvio-lacustrine sequences in the Nihewan Basin and its implications for early human colonization of Northeast Asia[J]. Quaternary Sciences, 27(6): 922—944(in Chinese). [本文引用:1]
59	Cand e S C, Kent D V. 1995. Revised calibration of the geomagnetic polarity timescale for the Late Cretaceous and Cenozoic[J]. Journal of Geophysical Research, 100(B4): 6093—6095. [本文引用:1]
60	Deng C L, Hao Q Z, Guo Z T, et al. 2019. Quaternary integrative stratigraphy and timescale of China[J]. Science China Earth Sciences, 62: 324—348. [本文引用:1]
61	Kirschvink J L. 1980. The least-squares line and plane and the analysis of palaeomagnetic data[J]. Geophysical Journal of the Royal Astronomical Society, 62(3): 699—718. [本文引用:1]
62	Qiao Y S, Guo Z T, Hao Q Z, et al. 2003. Loess-soil sequences in southern Anhui Province: Magnetostratigraphy and paleoclimatic significance[J]. Chinese Science Bulletin, 48(19): 2088—2093. [本文引用:1]
63	Zhang Y F, Li C A, Wang Q L, et al. 2008. Magnetism parameters characteristics of drilling deposits in Jianghan Plain and indication for forming of the Yangtze River Three Gorges[J]. Chinese Science Bulletin, 53(4): 584—590. [本文引用:4]

1979

0.0

... 磁性地层年代学方法已经成为平原和盆地地区第四纪地层序列和年代框架研究的有效方法(安芷生等, 1979 ...

1979

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2010

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... 柏道远等, 2010 ...

2010

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1987

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... 前人对武汉地区的第四纪地层(陈华慧等, 1987 ...

... 这可能与早更新世中期气温回升、降雨量增加(陈华慧等, 1987)导致沉积环境发生明显变化有关 ...

1987

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2007

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陈杰, Heermance R

, Burbank D

, et al. 2007. 中国西南天山西域砾岩的磁性地层年代与地质意义[J]. 第四纪研究, 27(4): 576—578.

Magnetostratigraphy of the Kashi foreland basin along the southern margin of the Tian Shan in western China defines the chronology of both sedimentation and the structural evolution of this collisional mountain belt. Five magnetostratigraphic sections representing ca.8.5km of distal basin strata provide a 2- and 3-dimensional record of continuous deposition since ca.5Ma. The distinctive Xiyu conglomerate makes up the uppermost strata in 4 of 5 magnetostratigraphic sections within the foreland and forms a wedge that thins southward. Age of the basal Xiyu conglomerate varies from 15.5Ma at the northernmost part of the foreland [1] , to 8.6Ma in the central (medial) part of the foreland [1] , and to 1.9 ＋0.05 -0.1 Ma, 1.6±0.1Ma, and 0.73±0.05Ma along the southern deformation front of the foreland basin. These data indicate that the Xiyu conglomerate is highly time-transgressive and has prograded southward immediately after the initial uplift of the Kashi Basin Thrust (KBT). This finding contrasts with previous studies which assumed that the Xiyu conglomerate is either Plio-Pleistocene in age or represents a chronostratigraphic unit. The southward gravel progradation occurred at an average rate of 2.5~3.5mm/a between 15.5Ma and 1.9Ma, before accelerating to ca.10~11mm/a. Results indicate a stepped migration of deformation into the Kashi foreland at least at 16.3Ma [1] , 13.5Ma [1] , 4.0Ma, and 1.4Ma. Progressive reconstruction of a seismically controlled cross section through the foreland produces total shortening of 13~21km and migration of the deformation front at 2.1~3.4mm/a between 16.3~13.5Ma, 1.4~1.6mm/a between 13.5~4.0Ma, and >10mm/a since 4.0Ma. Since 5Ma, increased sediment accumulation (ca.0.7mm/a) and gravel progradation rates (ca.10mm/a) appear linked to higher deformation rates on the Keketamu, Atushi, and Kashi anticlines and increased subsidence due to loading from both the Tian Shan and Pamir ranges. The accelerated erosion was possibly caused by climate change. Whereas the rapid (ca.10mm/a) progradation of the Xiyu conglomerate after 2Ma may be promoted by global climate change, its overall progradation since 15.5Ma is due to the progressive encroachment of deformation into the foreland. The tight temporal and spatial linkage between the migration of both the gravel front and the deformation front suggest a causal linkage between southward gravel progradation and pulsed migration of deformation. Tectonics is the fundamental control on conglomerate distribution within the Kashi foreland, although climate likely plays a role at shorter time scales.

①State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029; ②Department of Earth Science, University of California, Santa Barbara, CA 93106 USA; ③Department of Geology, Appalachian State University, Boone, NC 28608 USA

西域组是我国西部一重要并广泛引用的晚新生代地层,关于其年代和成因至今尚存争议。在西南天山喀什远源盆地喀什-阿图什褶皱带不同构造部位选择有代表性的5~6个晚新生代地层剖面开展了详细的沉积学、磁性地层年代学对比研究,据此限定了不同构造的起始变形时间以及西域砾岩的沉积年代。西域砾岩并非一年代地层单位,作为一岩石地层单位,其底界具有穿时特征,从山体(北)向喀什前陆盆地(南)逐渐变新。其底界年龄在盆地北部近源区约为15.5Ma [1] ,在盆地中部中源区约为8.6Ma [1] ,在盆地南部远源区的阿图什背斜为1.9Ma,喀什背斜为1.6~0.7Ma。这一穿时的砾岩沉积楔体的起始堆积起因于盆地北部边界逆冲断层(KBT)的活动。构造变形是由北南脉冲式迁移扩展的,其速率是非均匀的,在约15.5Ma至4.0Ma期间为1.4~3.4mm/a,在约4.0Ma以来剧增至>10mm/a。西域砾岩沉积前缘向南进积速率与构造变形前缘迁移速率有很好的一致性,但在时间上较构造变形可能滞后2.0Ma。这表明构造变形前缘向南的脉冲式扩展是西域砾岩进积并发生侧向和垂向上岩相突变的主因。

... 陈杰等, 2007 ...

2007

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2008

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陈宇坤, 李振海, 邵永新, 等. 2008. 天津地区第四纪年代地层剖面研究[J]. 地震地质, 30(2): 383—398.

Based on the optical dating and paleomagnetic testing results,we make a chronostratigraphic research of Huanghua depression and Cangxian uplift which are two tectonic units of Tianjin area.In this paper,we establish a Quaternary stratigraphic section and make a new division of the Quaternary strata.The result shows that the two tectonic units have similar sedimentation histories,but many differences exist.On the one hand,both units have received transgression since the Quaternary and some marine strata formed to various extents,which indicates different transgression sedimentation histories between them;on the other hand,the Quaternary stratigraphic sequences of the two units are greatly different,indicating different sedimentation histories,and consequently,the type and thickness of sediments are obviously different,so they belong to different sedimentary units.The study also shows the depths of bottom interfaces of Holocene,upper Pleistocene and middle Pleistocene as 19m,45m and 103m,respectively in hole BZ1 in Huanghua depression and 13m,30m and 56m respectively in hole BZ2 and hole TN3 in Cangxian uplift.The depth of bottom interface of the Quaternary is about 162m,much smaller than the result of the previous Quaternary strata division.

Earthquake Administration of Tianjin Municipality, Tianjin 300201, China

通过钻孔岩心光释光测年与古地磁测试,对天津地区黄骅坳陷和沧县隆起两个构造单元的年代地层进行了研究,对区内第四纪分层界线重新进行了划分,建立了本区第四纪年代地层剖面。黄骅坳陷和沧县隆起两个构造单元的沉积发展历史具有一定相似性,同时还存在较大的差异。主要表现在:第四纪以来,黄骅坳陷和沧县隆起均有海侵发生,沉积一些海相地层,但是其发育程度不同,反映两个构造单元有着差异较大的海侵历史;二者在第四纪年代地层序列上存在较大差异,形成的相应沉积物的类型和厚度明显不同,为两个不同的第四纪沉积单元;天津地区原来第四系内部的分层界线为:Q h 埋深20m,Q p 3 为70～80m,Q p 2 为180～210m,Q p 1 为400m。研究表明,天津地区的第四系在黄骅坳陷和沧县隆起上明显不同:黄骅坳陷中的全新统、更新统上段及中段底界深度约分别为19,45,103m,第四系底界深度>200m;沧县隆起上的全新统、更新统上段及中段底界深度分别为13,30,56m,而第四系底界埋深为162m左右,远远浅于原来第四系分层的界线。

... 陈宇坤等, 2008 ...

2008

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1991

0.0

... 武汉市近地表90%为第四系所覆盖(邓健如等, 1991), 即武汉市城市建设的主要承载地质体为第四系 ...

1991

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1998

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... 2 武汉地区第四纪地层的沉积速率古地磁年表的建立不仅可以为地层划分对比提供年代学依据, 而且可以反映出不同地质时期沉积厚度和沉积速率的变化, 从而为研究第四纪古地理的环境变化提供依据(范代读等, 1998) ...

1998

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1990

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... 关康年等, 1990 ...

1990

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1994

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黄宝春, 谭承泽. 1994. 古地磁多磁成分的分离技术[J]. 地球物理学进展, 9(1): 125—134.

In palaeomagnetism a reliable and rational palaeomagnetic data should be come from the original remanent component, which represents the direction of palaeomagnetic field when the rock formed. So, it is of great importent and valuable to acquire the original remanent direction from complex demagnetization data obtained in the laboratory. The aim of this paper is to make a systematic study about this subject. In this paper, A new method of multi-component separation is proposed based on the combination of the method of the Principle Component Analysis, Linearity Spectrum Analysis and the best fit great circles of the poles of the remagnetization circles and the demagnetization planes.

1. Institute of Geophysics, Academia Sinica, Beijing 100101; 2. China University of Geosciences, Beijing 100083

在古地磁的研究中，如何从复杂多样的退磁数据中获取能够代表岩石形成时期的古地磁场方向的原生剩磁组分，是关系到古地磁数据是否可靠、古地磁结果是否令人信服的根本环节之一，因此，如何充分利用实验室退磁数据所提供的各种信息去获取同源磁化的一组样品的原生剩磁方向是一个很有研究价值的问题。在总结前人的各种定性或定量的多磁成分分离技术的基础上，详细讨论了重磁化大圆的极和线性坳陷区内退磁平面的极的最佳拟合大圆的最小二乘拟合法，提出了综合使用主成分分析法、线性谱分析法、重磁化圆法以及退磁平面及重磁化大圆的二次拟合法，对来自同源磁化的一组样品进行系统分析，以获取一组样品的特征剩磁方向的方法，并应用于实际研究工作中。

... 黄宝春等, 1994), 并采用最大角偏差(MAD: The biggest angle deviation mad)判断一组数据是共线还是共面, 当其小于给定的MAD临界值(本文取15#cod#x000b0 ...

1994

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1993

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... 黄宁生等, 1993 ...

1993

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2015

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... 霍炬, 2015), 已有研究结果无法满足多要素城市地质调查的需要 ...

2015

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1997

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... 网纹红土是长江中下游以南地区非常典型的第四纪土状堆积物, 前人的研究表明, 其古地磁年代属于布容极性时(蒋复初等, 1997 ...

1997

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1992

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金国海, 方大钧, 吴能友. 1992. 多剩磁成分的主成分法分离及其应用[J]. 地球物理学报, 35(5): 621—629.

Separation of multi-components becomes an important part in paleomagnetism. By employing the method of principal component analysis（PCA） suggested by Kirschvink （1980）, we may isolate the directions of multi-components effectively. Special emphasis has been placed on the choice of MAD value with respect to the combination of remanent spectrum. Remanent similarity defined by the authors could help to confine the upper limit of MAD value. Based on the directions of isolated components derived from PCA method, a method for separation of magnetic component in intensities is suggested. Its validity has been demonstrated through examples of pilot specimens of Late Paleozoic from Kepin region, Xinjiang.

Department of Earth Sciences, Zhejiang University, Hangzhou 310027

岩石的多剩磁成分的分离是古地磁研究的重要环节之一.Kirschvink（1980）提出的主成分分析法（PCA）能有效地进行多剩磁成分的方向分离.作者认为,最大角偏差（MAD）值的选择应视各磁成分的剩磁谱组合特征而定,剩磁相似度的提出,可以帮助确定MAD值选取的最佳值.在主成分法分离的剩磁方向的基础上,作者提出了一种多剩磁成分的强度分离方法,籍此可以进一步研究各分离磁组分的剩磁谱特征及其成因,并将以上方法应用于新疆柯坪地区晚古生代地层的剩磁分离.

... 金国海等, 1992 ...

1992

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1987

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... 田望学等, 2011)及年代学(康悦林, 1987 ...

1987

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1997

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... 李长安等, 1997 ...

1997

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2011

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... 但其中大部分为针对出露有限的地表露头的研究, 虽有钻孔研究, 也仅针对第四纪晚期的某一时段(林晓等, 2011 ...

2011

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2005

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刘进峰, 郭正堂, 郝青振, 等. 2005. 甘肃秦安糜子湾剖而中新世风尘堆积的磁性地层学研究[J]. 第四纪研究, 25(4): 503—509.

Earlier studies on two sections (QA-Ⅰ and QA-Ⅱ) in the Qin′an County from the western Loess Plateau demonstrated that loess deposits started by 22MaB.P., indicating the onset of Asian desertification and winter monsoon circulation by the Early Miocene time. Another Miocene loess section, Miziwan section with a thickness of 164.4m, 30km in east to the QA-Ⅰ section, is geomagnetically dated in this study.

1. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029; 2. State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi′an 710075; 3. Department of Tourism Resource and Environment Sciences, Taishan College, Tai′an 271000; 4. Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081

文章对西部黄土高原糜子湾黄土-古土壤剖面进行了磁性地层学研究。该剖面厚度为164.4m,记录了15个正磁极性段和15个负磁极性段,可与标准极性表中从C5r.3r到C5En之间的极性带对比。根据极性界限用平均沉积速率外推,得到该剖面顶界年龄为约11.6MaB.P.,底界年龄为约18.5MaB.P.。糜子湾剖面位于已发表的QAⅠ中新世黄土剖面以东约30km,两剖面相同时代的地层在岩性地层结构和磁化率曲线波动上具有高度的一致性,表明中新世黄土-古土壤序列与第四纪黄土-古土壤序列一样,地层在空间上有很好的可对比性。文章的结果为从空间角度研究中新世环境变化行为提供了新剖面的年代地层框架。

... 刘进峰等, 2005 ...

2005

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2006

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乔彦松, 赵志中, 王燕, 等. 2006. 川西甘孜黄土磁性地层学研究及其古气候意义[J]. 第四纪研究, 26(2): 250—256.

Eolian deposit is widely distributed in West Sichuan Plateau. In this paper, a loess-soil sequence near Ganzi Temple in Ganzi County of Sichuan Province is dated using geomagnetic and luminescence methods. The studied section is 15.3m thick and consists of 26 field definable lithological units. 40 oriented paleomagnetic samples were taken at 20~40cm intervals from the Ganzi Temple section. Measurements were carried out in the Paleomagnetism Laboratory, Institute of Geomechanics, Chinese Academy of Geological Sciences. Stepwise thermal demagnetization up to 620℃ was performed on all 40 samples using a TD-48 thermal demagnetizer with a temperature step of 20~50℃. Measurements were made using a 2G-755 three-axis cryogenic magnetometer.The reverse boundary between the Brunhes normal zone and the Matuyama reversed zone is recognized at the top of S 8 , and the Jaramillo normal subzone occurs in the lower part of this sequence at a depth of 12.7 ~14.0m. Two boundary ages of Jaramillo normal subzone (0.99MaB.P. and 1.07MaB.P.) suggest an average eolian accumulation rate of about 1.625cm/ka in this period. Extrapolation with this accumulation rate yields a basal age of about 1.15MaB.P. at the Ganzi Temple section. Eolian deposit older than 1.15MaB.P. has never been reported in West Sichuan Plateau, which indicates that eolian deposition in this region started at about 1.15MaB.P. Morphological features of quartz grains from the Ganzi Temple section indicate that the eolian dust in Ganzi may be from the materials of glaciation and melting ice. The results of magnetostratigraphy and morphology of quartz grains suggest a climatic event at about 1.15MaB.P. in West Sichuan Plateau, which was interpreted as a result of both the reduction of vegetation near Ganzi area and the strengthening of winter monsoon associated with the uplift of the Tibetan Plateau. In addition, the result of magnetostratigraphy is favourable for the studies of climatic change and neotectonic movement in this region.

Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081

文章对川西甘孜地区甘孜寺剖面进行了系统的磁性地层学研究及石英颗粒表面形态特征分析。磁性地层学研究结果显示,B/M界线出现在S 8 的顶部,并且在剖面下部12.7~14.0m处出现了松山负向期的贾拉米洛正向极性亚带。本次测试以及结合以前的研究结果表明,甘孜地区典型的风尘堆积形成于约1.15MaB.P.以前。石英颗粒表面形态特征的分析结果说明风尘物质可能经历了风、流水、冰川等多种外动力作用,进一步证明该区的风尘物质主要来源于青藏高原及其周缘地区的冰水沉积。另外,研究结果指示青藏高原及其周缘地区的环境状况大约在1.15MaB.P.发生了很大变化,主要表现为干旱化程度以及高原冬季风的明显增强,而这些变化又与青藏高原在该时期的快速隆升密切相关。磁性地层的研究结果将为在该区进一步开展古环境演化过程的对比分析及阶地地貌发育历史的研究奠定基础。

... 乔彦松等, 2006 ...

2006

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2011

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... 田望学等, 2011)及年代学(康悦林, 1987 ...

2011

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2006

0.0

... 南京泰山新村剖面和燕子矶剖面的古地磁年代测定结果(武春林等, 2006)可知, 布莱克(Blake)亚时位于剖面中下部, 与本钻孔布莱克(Blake)亚时出现的层位大致相当 ...

2006

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2008

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肖国桥, 郭正堂, 陈宇坤, 等. 2008. 渤海湾西岸BZ₁钻孔的磁性地层学研究[J]. 第四纪研究, 28(5): 909—916.

The Quaternary deposits in the coast of Bohai Bay provide an important archive for addressing Quaternary sea-level changes,interactions between marine and terrestrial environment,and Neotectonic movements.Here we present the magnetostratigraphic results of BZ1 borehole(204.51m)near Tianjin which is located at Huanghua Depression in this region.A total of 417 undisturbed samples were collected from BZ1 borehole at an interval of 0.2～0.8m except for several missing intervals during drilling.290 samples were performed on thermal demagnetization in temperature steps of 20～50℃ until 585℃ or 680℃.Another 127 samples were performed on progressive alternating field demagnetization at peak fields up to 60mT at 5～10mT intervals.Magnetizations were measured by a 2G-760 U-Channel system and performed in the Paleomagnetism and Geochronology Laboratory of the Institute of Geology and Geophysics,Chinese Academy of Sciences where magnetometers and demagnetizers are installed in magnetic shielded house with a field minimized to less than 300nT.Demagnetization results were evaluated on stereographic projections and orthogonal(Zijderveld)diagrams,and standard Fisherian methods were performed to calculate the characteristic remanent magnetization(ChRM)directions.Only about 10.6% of the samples which showed unstable demagnetization trajectories couldn't isolate ChRM directions.The Brunhes/Matuyama boundary is found at the depth of 102.43m.The interval from 102.43m to 204.51m is fairly correlative with the Matuyama reversal in the geomagnetic polarity timescale with two normal polarity zones corresponding to Jaramillo(130.21～133.53m)and Olduvai(159.51～178.05m)subchrons,respectively.The basal age of BZ1 borehole is estimated at about 2.21Ma by extrapolation of the sedimentation rate in the Olduvai subchron.Our results have provided a reliable chronology framework for paleo～environment and related research in this area.The sedimentation rates of the BZ1 core during the past 1Ma is relatively high(ca.132m/Ma)compared with the interval of 1.00～2.21Ma.The thickness of the deposits of this core is 102.4m and around twice of that of the BZ2(56.2m),another borehole located at Cangxian Uplift which we reported previously,during Brunhes epoch,suggesting that the sedimentation rates controlled by Neotectonic movement are quite different between these two tectonic units and that an epoch of Neotectonic movement occurred around 1Ma,which led to accelerated subsidence of the Huanghua Depression compared with that of the Cangxian Uplift.Whilst,the transgression revealed in the upper ca.60m of the BZ1 borehole sequence,contrary to the decreasing global seal level since 800kaB.P.,may be resulted from the accelerated subsidence of the Huanghua Depression since 1Ma.

1. State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710075; 2. Graduate University of Chinese Academy of Sciences, Beijing 100049; 3. Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences 100029; 4. Earthquake Administration of Tianjin Municipality, Tianjin 300201; 5. Institute of Geology, China Earthquake Administration, Beijing 100029

文章对位于渤海湾西岸黄骅坳陷内的BZ1钻孔进行了详细的磁性地层学研究。结果表明,204.51m的岩芯记录了布容正向极性时(Brunhes)、贾拉米洛(Jaramillo)和奥尔都维(Olduvai)极性亚时,钻孔底部年龄约为2.21Ma。本项研究结果为该区约2.21Ma以来的古环境和相关研究提供了可靠的地层年代框架。与沧县隆起区的BZ2钻孔地层结果对比表明,两个构造单元的沉积物厚度在布容期以来差异较大,即在此期间黄骅坳陷相对沧县隆起下沉40余米,表明1Ma前后发生的新构造运动导致黄骅坳陷区构造下沉速率显著增加。

... 肖国桥等, 2008 ...

2008

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2007

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王喜生, 杨振宇, Lφvlie

, 等. 2007. 松山—布容地磁极性倒转在黄土高原东南缘记录的可靠性探讨[J]. 第四纪研究, 27(6): 963—971.

The recording inconsistencies of magnetic polarity reversals among many Chinese loess sections and between the loess and the marine records have hampered precise section-to-section and land-ocean age comparisons. To better assess the fidelity of polarity reversals and precisely estimate the extent of lock-in depth of the remanence magnetization in Chinese loess, we present a high-resolution paleomagnetic and detailed mineral magnetic investigation of a loess section at Sanmenxia.

1. Laboratory of Paleomagnetism,Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081; 2. Department of Earth Science, Nanjing University, Nanjing 210093; 3. Department of Earth Science, University of Bergen Allegaten 41, N-5007 Bergen, Norway

中国黄土的剩磁获得机理和Lock-in深度问题是目前黄土古地磁研究的焦点和核心问题之一,它直接关系到黄土时间标尺的精确度和海陆古气候对比的可靠性。文章以黄土高原东南缘三门峡曹村剖面获得的高分辨率古地磁极性界线作为年代控制点,通过黄土-古土壤序列1.1Ma以来的磁气候记录与近年来中、高纬度大西洋ODP/DSDP钻孔中获得的具有高分辨率古地磁年代约束的深海氧同位素记录进行了详细对比分析,提出与传统的海陆对比不同的基于古地磁界线的海陆对比方案:松山/布容地磁极性转换界线记录在曹村剖面S8的顶部,可对应深海沉积的MIS19,而不是前人认为的MIS21。黄土高原不同地区记录东亚冬、夏季风的差异性和变化性可能是全球具同时性的松山/布容地磁极性转换在黄土高原不同地区产出层位不一致性的主要原因,而基于Lock-in模型的天文年代标尺则可能高估了黄土/古土壤的年龄。

... 王喜生等, 2007 ...

2007

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2007

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许炯心. 2007. 基于大样本¹⁴C测年资料的华北平原沉积速率研究[J]. 第四纪研究, 27(3): 437—443.

The North China Plain is an area where much research in Quaternary geology has been done and a large number of 14 C dating data is available from published materials. Extracting information of plain sediment depositional rate from these data and then studying the temporal variation of depositional rate in relation with varying natural conditions and human activities is an issue of great importance. Using 14 C dating data from 456 locations in the North China Plain, average depositional rate ( R T ) for the period from the year when the sample was deposited to present has been calculated, and the temporal variation in R T are plotted. The resulting curve shows an increasing trend in the past 40000 years. The upper envelop line of the scattering points is used to reflect the maximum values of R T , which is referred to as R T,max . This index reflects the deposition of the lower Yellow River Plain, the main body of the North China Plain. The fitted upper envelop line indicates 4 breaks, occurring in the time of 10000aB.P. , 5000aB.P. , 3000aB.P. , and 1400aB.P. , respectively. The 4 breaks divide the fitted line into 5 straight-line segments, representing 5 stages of plain sediment accumulation in the past 40000 years. The slope of the 4 segments increases, reflecting the accelerating process in the plain deposition. An explanation has been given to the formative cause of the 4 breaks. Stages 1, 2, and 3 occurred due to natural environmental changes, and stages 4 and 5 was due to the joint influence of both natural and human factors. Information has been extracted from 456 samples for estimating the average depositional rate of the whole North China Plain during a period of 40000 years, which has been calculated as 0.9mm/a, and thus, the total sediment thickness in the past 40000 years has been estimated as 36m in the plain.

Institute of Geographical Sciences and Natural Resources Research, Key Laboratory for Water Cycle and Related land Surface Processes, Chinese Academy of Sciences, Beijing 100101

华北平原是我国研究程度较高的地区,历年来积累了大量的 14 C测年资料。从这些资料中尽可能地提取沉积速率的信息,并进而研究华北平原沉积速率的变化及其与流域自然和人文环境变化之间的关系,是一个有重要意义的问题。利用华北平原456个地点的 14 C年龄与样品埋深资料,计算出了各个样品所在层位沉积以来的平均沉积速率( R T ),以此来近似反映各地点的平原沉积速率,并据此建立了 R T 随时间的变化关系。从古至今, R T 有明显的增大趋势。以点群的上包线反映各时代的平原最大沉积速率,该指标可以反映华北平原的主体即黄河下游冲积平原的沉积速率。发现了最大平均沉积速率随时间变化过程中的4个突变点,分别为10000aB.P. , 5000aB.P. , 3000aB.P. 和1400aB.P. 。4个突变点将上包线分成5条折线,由此可以将近4万年以来的变化分成5个阶段。从古至今,5条折线的斜率增大,反映了平原沉积的加速过程; 并对4个突变点的成因进行了解释。阶段1,阶段2和阶段3沉积速率的加速是由自然原因造成的; 阶段4和阶段5沉积速率的加速则是由自然和人为原因共同造成的。从456个地点的 14 C年龄与样品埋深资料中提取了距今4万年以来华北平原的平均沉积速率的信息,计算出平均沉积速率为0.9mm/a。按此求出,近4万年以来华北平原的沉积总厚度为36m。

... 具体做法为: 设相邻2个年龄控制点的埋深分别为为H₁ 和H₂,年龄分别为T₁ 和T₂,则2个年龄控制点之间的沉积厚度为H₂-H₁,年代间距为T₂-T₁,通过 RT2T1=(H2-H1)/(T2-T1)计算得到T₂ 到T₁ 的平均沉积速率 RT2T1,然后可以利用线性方程求得这2个年龄控制点埋深之间任意点的年龄(许炯心, 2007) ...

2007

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1996

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... 10MaiBP(杨浩等, 1996 ...

1996

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2008

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杨勇, 李长安, 胡思辉, 等. 2008. 武汉青山 “砂山”粒度特征及其成因指示[J]. 沉积学报, 26(3): 487—493.

Based on the grain-size analyses of representative section of Qingshan “sand-dune” in wuhan, the causes of “sand-dunes” is discussed in this paper. The results show as follows: Qingshan “sand-dune” mainly consists of sand with the average content over 59%, while 23% coarse silt and 11% fine silt approximately, only little in clay content. The characteristics of grain size parameters is same as typical sand dune, frequency distribution curves with two crests, and probability cumulative curves with a pattern of two segments, partly three, and high content of saltation load, closely resemble that of eolian sediments, C-M chart and statistical indices of grain size distribution different with fluvial sediment obviously, the discriminant analysis result is mingled with plus-minus. With a brief calculation, “sand-dunes” are fluvial sediment which outcropped in the last glaciation blown and conveyed by wind, then deposit in the south bank of Yangtze River.

China University of Geosciences, Graduate School Wuhan 430074

根据代表性的武汉青山“砂山”的粒度分析探讨“砂山”的成因。结果表明：剖面砂颗粒含量较高，平均达５９％，粗粉砂约２３％，细粉砂约１１％，黏土含量少。粒度参数特征与典型沙丘砂一致，频率分布曲线为双峰，概率累积曲线为两段式，部分层位三段式，跃移质含量高，显示风积成因，Ｃ—Ｍ图及结构参数散点图与河流沉积物差别明显，判别分析结果正负夹杂。综合看来，“砂山”是末次冰期时出露的河流沉积物经风力吹扬、搬运，在长江南岸堆积而成。

... 杨勇等, 2008)等曾做过一些研究, 也取得了一定进展 ...

2008

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2008

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袁宝印, 夏正楷, 李保生, 等. 2008. 中国南方红土年代地层学与地层划分问题[J]. 第四纪研究, 28(1): 1—13.

Red soil in southern China is distributed to the north till the south of the Qinling Mountain-Huihe River line,and to the west till the east of Tibet,with an area of about 200×104km 2 .It has the widest distribution in the form of Quaternary earthy deposits in China.Abundant information about geology,environment,climate,and Paleolithic culture has been available on it.It's significance can be compared favourably with loess deposits in North China.In this paper,we only focus on the red weathering crusts developed on the Quaternary loose sediments.The Quaternary loose sediments in southern China mainly consist of beach sand and coastal dune sand-the "Old Red Sand",fluvial sediments and eolian deposits including Xiashu loess.Recently,some Paleolithic sites have been found in these deposits,which facilitate study of the chronostratigraphy of the red soil.Firstly this paper focuses on exploring the forming mechanism of the red weathering crust on the Quaternary loose sediments.Secondly we provide the results of chronostritigraphy of red weathering crust in Baise Basin of Guangxi Province,Wenchang County of Hainan Province,Jingjiang Region of Fujian Province,and Xuancheng Area of Anhui Province.The accumulation period of the parent material and the ages of the red weathering crust were discussed.The contemporaneous zoning pattern of the red weathering crust during the climate change process was also discussed.

1. Institute of Geology and Geophisics, Chinese Academy of Sciences, Beijing 100029; 2. Laboratory for Earth Surface Processes, Department of Geography, Peking University, Beijing 100871; 3. Geography College, South China Normal University, Guangzhou 510631; 4. Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081; 5. Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Scinces, Beijing 100044

南方红土是我国热带、亚热带以各类岩石和第四纪松散沉积物为母质发育的红色风化壳,也是我国分布最广的第四纪土状堆积。本文在探讨第四纪松散沉积物上红色风化壳的形成机制的基础上,根据风化壳发育程度将其划分为砖红土风化壳、红壤土风化壳和红化土风化壳3种类型。南方地区第四纪松散沉积物主要有河流相沉积、滨海相海滩砂和海岸风成砂——"老红砂"以及以下蜀土为主的风尘堆积。近年来在上述沉积物中多处发现旧石器遗址,促进了南方红土的地层年代学研究。根据前人及近期对南方红土的研究成果,讨论了南方红土的年代地层学问题,提出了以风化壳岩性特征为基础的岩石地层单位初步划分框架:老红砂划分为中更新统北海组、晚更新统晋江组;风尘堆积划分为中更新统宣城组、晚更新统下蜀组;河流相沉积只划出中更新统白沙井组,晚更新统留待以后研究再划出。

... 袁宝印等, 2008) ...

2008

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1995

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... , 2008)和R25孔(张景鑫, 1995)相似, 难以与标准极性柱准确地一一对应, 这可能与江汉盆地第四纪沉积粒度较粗有关 ...

1995

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2017

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... 张磊等, 2017) ...

2017

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2007

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朱日祥, 邓成龙, 潘永信. 2007. 泥河湾盆地磁性地层定年与早期人类演化[J]. 第四纪研究, 27(6): 922—944.

The Nihewan Basin is located in the transition zone between the North China Plain and the Inner Mongolian Plateau. The basin is filled with Late Pliocene to Holocene lacustrine, fluvial, and wind-blown deposits. The Nihewan Formation comprises the whole fluvio-lacustrine sequence in the Nihewan Basin, which is overlain by the wind-blown loess sediments of the Holocene, and/or the last glacial period, and/or the interglacial period, and underlain by the Late Pliocene red clay of eolian origin. The timing of the Nihewan Formation rich in mammalian faunas and Paleolithic sites in the Nihewan Basin is critical to our understanding of a series of important issues, such as early human adaptability to the hostile environments in high northern latitudes, infilling process of the Nihewan Basin, and chronological sequence of the Nihewan faunas.

State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029

主要评述了近年来泥河湾盆地磁性地层学的研究进展,包括建立泥河湾组的磁性地层年代格架、厘定泥河湾动物群的时代和确定华北地区早期人类活动年代序列。研究表明:第一,泥河湾组河湖相沉积序列记录了高斯正极性时末期以来的地磁极性特征（松山和布容极性时）,即沉积时代始于约2.6Ma。早期人类至少在1.66 0 .78Ma期间的大约90万年的时间内长期持续地占据高纬度的泥河湾盆地。泥河湾动物群（包括广义和狭义）的时代为2.0 0 .8Ma。第二,华北地区早期人类已经能够适应东亚高纬度地区冬季风增强、夏季风减弱和干旱化趋势增强的复杂环境变化,尤其能适应中更新世气候转型前后中国北方多变而且不稳定气候条件和生态环境。因此,气候和生态环境的多变性与不稳定性是促进人类进化的重要因素。第三,早期人类走出非洲以后,可能沿不同的路径并以较快的速度扩散到东亚地区。向南越过印度尼西亚的赤道地区,向北至少扩散到40°N的泥河湾盆地。

... 朱日祥等, 2007 ...

2007

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1995

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... 1 SK2钻孔磁性地层年代框架图 3为基于得到的稳定特征剩磁样品的磁倾角数据建立的SK2钻孔磁极性柱与标准极性柱(Cande et al ...

2019

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... 磁性地层学是当前建立第四纪年代地层框架的重要手段(Deng et al ...

1980

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... 通过最小二乘拟合法确定出剩磁组分数据新的坐标轴(Kirschvink, 1980 ...

2003

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... Qiao et al ...

2008

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... 结合前期的研究结果(Zhang et al ...

... 武汉地区位于江汉平原东缘, 为典型的陆相沉积环境, 这就决定了其磁性地层研究的相对复杂性(Zhang et al ...

... 周老孔(Zhang et al ...

... 这与前期得到的江汉平原钻孔的研究结果具有较好的一致性(Zhang et al ...