金坛-如皋断裂北东段浅层地震勘探新证据

引用本文

顾勤平, 杨浩, 赵启光, 孟科, 王金艳, 李云, 马董伟. 金坛-如皋断裂北东段浅层地震勘探新证据[J]. 地震地质, 2019,41(3): 743-758.
GU Qin-ping, YANG Hao, ZHAO Qi-guang, MENG Ke, WANG Jin-yan, LI Yun, MA Dong-wei. NEW EVIDENCE ON NE-SEGMENT OF JINTAN-RUGAO FAULT DISCOVERED BY SHALLOW SEISMIC EXPLORATION METHOD[J]. SEISMOLOGY AND GEOLOGY, 2019,41(3): 743-758. 复制到剪切板

DOI:10.3969/j.issn.0253-4967.2019.03.013
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金坛-如皋断裂北东段浅层地震勘探新证据

顾勤平^1,²⁾, 杨浩¹⁾, 赵启光¹⁾, 孟科¹⁾, 王金艳¹⁾, 李云³⁾, 马董伟⁴⁾

1)江苏省地震局, 南京 210014

2)中国地震局地球物理研究所, 北京 100081

3)南京地质矿产研究所, 南京 210016

4)上海申丰地质新技术应用研究所有限公司, 上海 201107

〔作者简介〕顾勤平, 男, 1983年生, 高级工程师, 2019年于中国地震局地球物理研究所获固体地球物理学专业博士学位, 主要从事浅层地震勘探、活断层探测及天然地震层析成像研究工作, 电话: 025-84285628, E-mail: gqp1221@163.com。

收稿日期: 2018-04-11

基金项目: 中国地震重点监视防御区活动断层探测之栟茶河断裂活动性鉴定项目(1530601)、国家自然科学基金(41704052)和中国地震局地震科技星火计划项目(XY18017Y)共同资助

摘要

NE向的区域性深大断裂——金坛-如皋断裂为苏北坳陷区和南通隆起区的分界断裂。为了调查金坛-如皋断裂北东段的空间位置、性质和断裂构造特征并重新厘定其活动性, 文中在石油地震勘探剖面提供的金坛-如皋断裂北东段大体空间位置及反射标志层的基础上, 布设了4条浅层人工地震勘探剖面, 对金坛-如皋断裂北东段进行了高分辨率地震反射成像, 获得了测线控制范围内清晰的地下结构和断裂构造成像结果。结果表明, 金坛-如皋断裂北东段并非单一的一条断层, 而是由2条N倾、 NEE走向的正断层组成的断裂带。浅层地震叠加剖面揭示活动性更强的南支上断点埋深235~243m, 断错了下更新统底界, 结合测线周边的钻孔资料推测其最新活动时代为第四纪早更新世(QP1)。文中的研究结果为确定金坛-如皋断裂北东段的位置及其活动性评价提供了可靠的地震学资料。

关键词: 金坛-如皋断裂; 北东段; 浅层地震勘探; 第四纪活动

中图分类号:P642.27 文献标志码:A 文章编号:0253-4967(2019)03-0743-16

NEW EVIDENCE ON NE-SEGMENT OF JINTAN-RUGAO FAULT DISCOVERED BY SHALLOW SEISMIC EXPLORATION METHOD

GU Qin-ping^1,²⁾, YANG Hao¹⁾, ZHAO Qi-guang¹⁾, MENG Ke¹⁾, WANG Jin-yan¹⁾, LI Yun³⁾, MA Dong-wei⁴⁾

1)Jiangsu Earthquake Agency, Nanjing 210014, China

2)Institute of Geophysics, China Earthquake Administration, Beijing 100081, China

3)Nanjing Institute of Geology and Mineral Resources, Nanjing 210016, China

4)Shenfeng Institute of Geological Techniques Co., Ltd, Shanghai 201107, China

Abstract

The NE-trending regional deep fault, i.e. the Jintan-Rugao Fault, is a boundary fault between the Subei depression and Nantong uplift, and its research has always received broad attention because of its importance and complexity. For the absence of definite proof, there is little consensus regarding the structure and spatial distribution of the fault among geoscientists, and its latest active time is ambiguous. The study of Quaternary activity characteristics of the Jintan-Rugao Fault is of great significance for earthquake trend prediction and engineering safety evaluation, and for earthquake prevention and disaster reduction in Jiangsu Province. In order to investigate the spatial location, characteristics and tectonic features and redefine the activity of the NE-segment of the Jintan-Rugao Fault, and on the basis of likely location and marker beds derived from petroleum seismic exploration sections, we collect and arrange 4 shallow seismic exploration profiles crossing the fault to conduct high-resolution seismic reflection imaging, following the working concept of ‘from known to unknown, from deep to shallow’. In this study, an observation system with trace intervals of 4~6m, shot intervals of 12~18m, and channels of 90~256 and 15~36 folds is used. In addition, by introducing different tonnage vibroseis to suppress the background noise, the raw data with high SNR(signal-noise ratio)can be obtained. By using the above working method and spread geometry, we obtained clear imaging results of the subsurface structure and fault structure in the coverage area of the survey lines. This exploration research accurately locates the NE-segment of Jintan-Rugao Fault, and further shows that it is not a single fault but a fault zone consisting of two normal faults with N-dipping and NE-striking within the effective detection depth. The shallow seismic profiles reveal that the up-breakpoint on the south branch with stronger activity is at depth of 235~243m, which offsets the lower strata of lower Pleistocene. Combining drilling data around the survey lines, we infer the activity time of this fault is early Pleistocene. The results of this paper provide reliable seismological data for determining the location and activity evaluation of the NE-segment of Jintan-Rugao Fault. In eastern China, where the sedimentary layer is thicker, the latest active age of faults can not be determined entirely according to the latest faulted strata. For a fault passing through the thicker area of new deposits, its latest active age should be based on the tectonic background, seismic activity, present tectonic stress field, topographic deformation, structural micro-geomorphological characteristics, sedimentary thickness of new strata, controlling effect of faults on new strata and the latest strata of faults, and combined with upper breakpoints, morphology, structure and occurrence of faults, the active state of the target concealed faults should be analyzed. If the activity of the fault is judged only by the upper faulted point, it may lead to overestimating the age of the fault activity.

Keyword: Jintan-Rugao Fault; NE-segment; shallow seismic exploration; Quaternary activity

文章图片

0 引言

NE向的金坛-如皋断裂是一条规模大、切割深、控制地层多的区域性大断裂(图 1中的F₁), 是2个三级构造单元(通扬隆起和海安凹陷)的分界断裂, 其两侧地质构造特征在地史各阶段存在着明显差异, 特别是新生代以来差异更为显著。该断裂被栟茶河断裂(图1中的F₂)切割成2段, 南西段从常州市金坛县经靖江生祠镇, 途经如皋, 呈NE向; 北东段始于河口镇, 经栟茶镇后入海, 呈NEE向(断裂分布见图1)。本文将对其北东段的构造特征及活动性进行论述。

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	图 1 测区地质构造和地震测线位置图 F₁金坛-如皋断裂; F₂栟茶河断裂; F₃国强镇-薛舍断裂。 b改编自 1:25万南通市幅基岩地质图Fig. 1 Geological structure and the location of seismic survey lines.

深部地球物理探测HQ-15线的解译图表明^①(① 张永鸿, 1985, 下扬子含油气区构造区划与含油气远景研究。), 金坛-如皋断裂为向NW倾的正断层, 至少下延至元古代变质岩系; 断裂以西新生界沉积巨厚, 尤其是古近系隆凹构造发育, 断裂以东属隆升区, 缺失古近系。断裂在重磁方面表现出以下特征^②(② 王明义, 1991, 江苏省苏中工区 1:5万重力测量成果报告。)^③(③ 张登明, 2003, 1:25万南通市幅区域地质调查报告。): 1)物理场区高、低值的分界线; 2)梯级异常带; 3)线性异常带; 4)异常带同步扭曲和拐折。金坛-如皋梯级异常呈NE走向, 在重力图上显示为密集的梯级带, 最大水平梯度可达1.5× 10^-5m/s²· km^-1, 两侧重力场特征截然不同, 北西侧异常轴向以NE向为主, 异常幅度明显降低, 多数为负值; 南东侧异常轴以EW向为主, 幅值普遍升高。对于石油剖面, 在黄桥地区的NW4310地震剖面上^①(① 江仁庆, 1982, 苏北黄桥地区地震普查成果报告。)

Tg⁰波组明显错动, 断裂的北西侧波组多、时深加大, 断裂的东南侧则无反射、波组中断。前人认为, 金坛-如皋断裂是一条长期活动的古断裂, 活动时间长、规模大且呈阶段性变化, 控制地层多, 是一条区域性深大断裂。上述成果很好地揭示了金坛-如皋断裂的中深部特征, 为研究其特征、演化及其动力学成因提供了丰富的深部构造信息。左丽琼等(2016)为寻找地热资源在金坛-如皋断裂北东段选取了7个微动测深点进行研究, 虽获取了各地层S波的速度结构特征, 但因测点间点距、断层平面位置误差较大, 最大有效探测深度约3 000m, 且对晚新生代地层的分辨仍然不够精细, 不足以对其位置、性质及最新活动时代进行评价。截至目前, 仍然未能见到专门针对金坛-如皋断裂北东段浅层地震勘探的系统研究成果以及针对该断裂空间位置、产状及活动性的新成果, 这直接影响着断裂周缘的城市规划和建设。

2015— 2017年, 依托财政部重点项目 “ 中国地震重点监视防御区活动断层探测与地震危险性评价项目” 的子课题 “ 栟茶河断裂活动性鉴定” , 本文针对金坛-如皋断裂展开了探测研究工作。在石油剖面探测结果的指导下利用高分辨浅层地震数据采集技术和数据处理方法, 首次较系统地取得了该断裂的叠加时间剖面, 获得了金坛-如皋断裂北东段清晰的浅部地层结构和断裂构造图像。最后, 本文依据地震叠加剖面并结合测线周边的钻孔资料, 对金坛-如皋断裂北东段的位置、产状以及断裂活动性进行了初步分析和研究, 为区域地震危险性评价及周缘的城镇规划提供了可靠的地震学依据。

1 测区地质构造和石油剖面概况

1.1 测区地质构造

金坛-如皋断裂为隆(通扬隆起)凹(海安凹陷)构造的边界, 是重要的地球物理场分界; 其北东段位于平原区, 被第四纪地层覆盖, 始于南通市如东县河口镇, 经栟茶镇后入海, 平面呈NEE向展布。 1:25万南通市幅区域地质调查报告^①(①张登明, 2003, 1:25万南通市幅区域地质调查报告。)表明, 两侧受其控制的地层发育存在较大差异。南侧白垩纪地层直接覆盖于晚古生代和中生代地层之上, 缺失古近系; 北侧属于凹陷区, 地层发育丰富, 古生代、中生代及新生代地层均有沉积, 并且古近纪地层厚度较大。晚新生代地层由南东向北西逐渐增厚, 在金坛-如皋断裂南东侧新近系的底界埋深约800m, 在北西侧逐渐增加至1 600m。断裂北西侧基岩为新生界古近系泰州组(E₁t)、阜宁组(E₁f)和三剁组(E_2-3s), 断裂南东侧基岩主要为下伏中生界上白垩统浦口组(K₂p), 局部为中生界下三叠统青龙组(T₁q)。

新近获得的紧临地震测线的1:5万区域地质调查钻孔资料^②(②刘宪光, 2016, 江苏省1:5万三仓镇、弶港镇、李堡镇、栟茶镇、岔河镇、白蒲镇幅区域地质调查报告。)表明, 该区域第四纪地层自下而上包括早更新世海门组( $Q_{P}^{1}$ h)、中更新世启动组( $Q_{P}^{2}$ q)、晚更新世昆山组( $Q_{P}^{3}$ k)与滆湖组( $Q_{P}^{3}$ g)以及全新世如东组(Qhr), 其埋深分别约285~310m、 175~195m、 93~115m、 70~80m及24m。松散沉积层和胶结成岩的基岩之间形成了很好的波阻抗界面, 且松散沉积层间存在砂和黏土的分界线, 满足开展浅地震勘探研究所需要的物性差异条件。

1.2 石油剖面

自20世纪50年代以来, 众多研究者(邱海峻等, 2006; 陈书平等, 2009; 冉怀江等, 2012)在海安凹陷盆地内进行的大量地震勘探工作表明, 金坛-如皋断裂对盆地的隆坳格局具有控制作用, 其经历了复杂的演化过程(陈书平等, 2009)。

石油地震勘探2005nh137d_s剖面(图2, 测线位置见图1)揭示, 盆地新生代以来的沉积层内部存在着多个反射能量强的反射波组; 同时, 在新近纪地层内出现了波组紊乱现象。新近系底界面反射能量较强, 表现为1个良好的波阻抗分界面(图 2中T_N), 本文将其作为后期浅层地震勘探的一个反射标志层。由图可见, 金坛-如皋断裂(F₁)表现为由2支N倾正断层组成的断裂带, 为犁式断层。其与北凌断层(F₄)相向而倾, 构成地堑, 对新生代早期(E+N)地层具有控制作用。石油剖面虽然能很好地控制金坛-如皋断裂(F₁)并揭露其深部结构形态, 但由于其观测系统忽略了浅部晚新生代的地层信息, 故不足以完成对金坛-如皋断裂的上断点位置及最新活动性的调查。为此, 基于2005nh137d_s石油勘探剖面提供的金坛-如皋断裂北东段大体的空间位置及最浅稳定反射标志层结果, 跨金坛-如皋断裂北东段布设了4条浅地震勘探剖面, 测线位置见图1。

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	图 2 海安盆地2005nh137d_s石油地震反射剖面 F₁金坛-如皋断裂北东段; F₄北凌断裂; F₅台西8井断裂Fig. 2 Oil seismic reflection section of profile 2005nh137d_s in Hai'an Basin.

图 3为控制栟茶河断裂(F₂)的85nh117.5石油地震反射剖面(位置见图1), 其与控制金坛-如皋断裂(F₁)北东段的2005nh137d_s石油剖面(图2)的相同点是, 2条石油剖面分别揭露的F₁和F₂断裂具有相同的犁式构造形态。不同的是, 85nh117.5剖面显示出栟茶河断裂的断距随深度加大, 具有更为明显的生长断层的典型特征和识别标志。本文给出该剖面旨在区分栟茶河断裂和金坛-如皋断裂北东段。由图可见, 栟茶河断裂北侧新生界内存在3个明显的角度不整合界面(图 3中的 $T_{E}^{1}$ 、 $T_{E}^{3}$ 及T_N), $T_{E}^{1}$ 为泰州组与下伏地层反射界面, $T_{E}^{3}$ 为阜二段与下伏地层反射界面, T_N为盐城组与下伏地层反射界面, 分别代表了仪征运动、吴堡运动及三垛运动(陈书平等, 2009)。综上所述, 金坛-如皋断裂北东段与栟茶河断裂的深部构造特征及产状不同。

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	图 3 海安盆地85nh117.5石油地震反射剖面(修改自陈书平等, 2009)Fig. 3 Oil seismic reflection section of profile 85nh117.5 in Hai’an Basin (adapted from CHEN Shu-ping et al., 2009).

2 浅层反射地震勘探方法

浅层地震反射勘探是厚覆盖区断裂探测最常用、最有效的方法之一, 该方法具有探测深度大、分辨率高及结果可靠等优点, 已经得到了广泛应用(方盛明等, 2002; 柴炽章等, 2006; 邓起东等, 2007; 何正勤等, 2007, 2010; 刘保金等, 2008; 顾勤平等, 2013, 2015; 许汉刚等, 2016)。浅层地震勘探能否取得好的效果取决于原始数据质量的好坏, 想要通过数据处理从丢失有效信息的地震资料中获得有用的结果往往是徒劳的(伊尔马滋, 1994)。本文从选用高性能地震仪器设备和适宜的震源以及选择最佳的观测系统等几个方面来保证获得最佳地震观测记录; 测线多采用夜间施工以确保原始数据的质量。

2.1 数据采集

2.1.1 地震仪器

采集设备的性能良好是获得可靠结果的重要因素(何正勤等, 2007)。本研究使用美国HPI公司生产的S-Land地震仪对测线Ⅰ 、 Ⅱ 和Ⅲ 进行实验, 在测线Ⅳ 上使用法国Sercel公司408UL型地震仪, 并搭配中国威海出产的PA-60型60Hz检波器。

2.1.2 地震波激发震源的选择

在石油剖面提供反射标志层(即基岩顶面T_N)的基础上, 为尽可能对基岩顶面做出有效探测, 本文在布设道间距为6m的测线Ⅰ 时使用了美国产28t的BV-300可控震源激发地震波, 通过试验确定的震源扫描频率为20~180Hz, 扫描长度为10s。在测线Ⅱ 、 Ⅲ 上使用保定北奥石油物探特种车辆制造有限公司生产的沙驼牌KZ03型可控震源, 其出力为29.6kN, 扫描频率为20~160Hz, 扫描长度为8s。对Ⅳ 测线使用炸药震源, 井深6m, 药量为0.3kg。

2.1.3 测线的布设及参数

测线Ⅰ : 受栟茶运河影响, 将河南段命名为Ⅰ -1, 河北段命名为Ⅰ -2。

测线Ⅰ -1: 施工方向自北向南。采用纵波反射勘探, 道间距6m, 偏移距72m, 于端点放炮, 216道记录, 36次覆盖, 测线长度为7 662m。

测线Ⅰ -2: 采集参数同测线Ⅰ -1, 测线全长3 954m; 施工方向自南向北。

测线Ⅱ : 道间距4m, 偏移距36m, 于端点放炮, 90道记录, 15次覆盖, 测线长度为3 752m, 施工方向自北向南。

测线Ⅲ : 采集参数同测线Ⅱ , 测线长度为2 444m, 施工方向自南西向北东。

测线Ⅳ : 道间距5m, 256道接收, 受炸药震源、河道影响, 多使用变观采集原始数据, 测线长度为11 200m, 施工方向自北向南。

测线均来自“ 栟茶河断裂活动性鉴定” 项目。其中, 测线Ⅰ 为项目控制性测线; 前人根据2条浅地震测线探测结果并综合钻孔资料分析认为栟茶河断裂属晚第四纪活动断裂^①(高中和, 2001, 南黄海地震区划研究报告。), 测线Ⅱ 、 Ⅲ 与前人^①(高中和, 2001, 南黄海地震区划研究报告。)布设的测线位置重合, 以检验早期勘探结果; 测线Ⅳ 为南京地质矿产研究所为完成南通洋口港海岸地质环境勘查所布设的地震勘探测线。

2.2 资料处理

采用GRISYS、 FOCUS等地震反射处理软件包对数据进行处理, 重点研究了提高地震记录信噪比和分辨率的方法, 在保证地震记录具有较高信噪比的前提下提高地震记录的分辨率。为达到提高反射波主频及其信噪比的目的, 首先进行了反褶积处理, 使处理后地震记录的高、低频反射波频谱具有相等的幅值; 然后采用频率滤波技术突出高频反射波。处理模块主要包括频率带通滤波、二维倾角滤波、正常时差校正(NMO)、共中心点(CMP)叠加、反褶积以及时变谱白化。叠后采用随机噪声衰减(RNATTE)压制噪声, 以提高剖面数据的信噪比和连续性。

2.3 不同道间距单炮记录特征分析

图4a、 b分别为道间距6m和4m的P波反射共炮点单炮记录。由图可见, 不同埋藏深度地震界面的反射波非常清楚; 此外, 不同道间距的单炮记录对浅层反射波的分辨不同。对比道间距为6m和4m的单炮记录可见, 两者均能够对双程走时(TWT)约800ms的基岩顶面做出有效探测并获得多组有效反射震相。但是, 在216道地震检波器接收、道间距6m的单炮记录上, 反射波 $T_{Q}^{3}$ (对应晚更新世地层底界面)仅出现在靠近炮点的50道地震检波器内, 远炮点已与直达波交会在一起; 而在90道接收的4m单炮记录上, 该反射震相清晰可见, 保证了满覆盖。因此, 缩小道间距有利于提高空间采样率, 获得更浅的界面反射波。综上所述, 本次探测工作所采用的4~6m道间距观测系统既能满足基岩面的追踪需求, 又可用来捕捉判定目标断裂是否属于地震活动断层的晚更新世地层底界面(中国地震局, 2005)。

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	图 4 不同道间距浅层地震共炮点记录Fig. 4 The common-shot gather of shallow seismic reflection in different trace intervals.

3 浅层地震反射剖面特征

经过数据处理后得到的水平叠加时间剖面, 其横坐标为桩号, 纵坐标为双程走时(TWT)。为了便于对剖面反射波组进行层组划分和地质解释, 收集了 1:20万基岩地质图的钻孔资料及近期获得的 1:5万区域地质调查资料中的钻孔资料^①(①刘宪光, 2016, 江苏省1:5万三仓镇、弶港镇、李堡镇、栟茶镇、岔河镇、白蒲镇幅区域地质调查报告。), 结合本次地震勘探资料进行分析, 将地质分层和地层年代划分结果标注于剖面右侧(图5)。

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	图 5 测线Ⅰ 地震反射波叠加时间剖面Fig. 5 Stack time section of seismic reflector in profile Ⅰ .

3.1 测线Ⅰ 地震剖面特征

图 5为测线Ⅰ 的叠加时间剖面图。由图可见, 剖面上的地层界面反射波发育明显, 新生代除新近纪地层各反射层均具有较强的反射能量和较好的横向连续性。 1:25万南通市幅区域地质调查报告结果^②(②张登明, 2003, 1:25万南通市幅区域地质调查报告。)表明盐城组(N_1-2yc)地层中存在火山岩, 故在叠加时间剖面上新近系内有效反射波组尤其是断裂以北较为紊乱, 不存在连续性较强的反射波组。参考 1:25万南通市幅区域地质调查报告^②(②张登明, 2003, 1:25万南通市幅区域地质调查报告。)及近期展开的 1:5万三仓镇、弶港震、李堡镇、栟茶镇、岔河镇、白蒲镇幅区域地质调查报告^①(①刘宪光, 2016, 江苏省1:5万三仓镇、弶港镇、李堡镇、栟茶镇、岔河镇、白蒲镇幅区域地质调查报告。)所获的钻孔资料(钻孔位置及其揭露的地层见图1), 解释了9组横向连续且能被可靠追踪的强反射同相轴。其中, 反射波T_N和T_Q分别为新近系和第四系的底界, 将 $T_{Q}^{2}$ — $T_{Q}^{3}$ 解释为第四纪覆盖层内部的地层反射波; 在T_Q反射波之下的新近系内部, 解释了4组较好的强反射波 $T_{N}^{2}$ — $T_{N}^{5}$ 。此外, 由于在该测线使用28t可控源激发地震波, 在基岩内部获得了反射能量较强的T_E反射波组, 该地震界面向N下倾加深, 其特征与石油剖面2005nh137d_s(图2)相吻合, 表明测线所控制的断裂就是金坛-如皋断裂北东段。总体而言, 剖面控制地段的Q+N底界反射波T_N在剖面上有较明显的起伏变化, 并在断裂附近出现Q+N层厚度的转变。

测线Ⅰ 非常清楚地揭示了断裂的构造特征, 基岩顶面反射T_N在F_1-1 断点两侧出现整体位错, 而在F'_1-1断点处除明显的运动学断错特征外, 在古近系内出现了向N倾、下倾加深的斜反射面T_E。根据剖面上的断点特征、平面的位置及基岩断点与石油剖面的吻合程度、古近系内N倾地震界面与石油剖面的一致性分析, 可以认为该剖面揭示的断点是金坛-如皋断裂北东段在地震叠加时间剖面上的反映, 断点的详细参数见表1。 F_1-1 断点断错的位置更浅, 活动性更强, 在剖面上能可靠分辨的断层上断点埋深为236~243m。

表1 浅层地震勘探解释的主要断点参数 Table1 Parameters of the main breakpoints of faults by the shallow seismic exploration

3.2 测线Ⅱ 地震剖面特征

图 6给出了测线Ⅱ 的叠加时间剖面图。剖面的总体特征与测线Ⅰ 极为相似, 从图上可识别出10组反射能量较强、横向连续性较好的地层反射, 包括第四系底界T_Q、新近系底界T_N、第四系内部的 $T_{Q}^{2}$ — $T_{Q}^{3}$ 、新近系内部的 $T_{N}^{2}$ — $T_{N}^{5}$ 以及古近系内部层位T_E。该测线和石油剖面、测线Ⅰ 同时具有的特点包括: 1)在断点北侧古近系内存在倾向N、下倾加深的地震反射界面T_E; 因在测线上使用了能量较小的3t可控源, 故T_E反射波能量和连续性弱于测线Ⅰ , 但仍能可靠分辨。 2)断点F_1-2 处基岩顶面发生整体断错。此外, 在新近纪地层内部的反射波组 $T_{N}^{3}$ — $T_{N}^{4}$ 呈现出短小、间断连续的特征, 推测仍与火山岩的存在有关。

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	图 6 测线Ⅱ 地震反射波叠加时间剖面Fig. 6 Stack time section of seismic reflector in profile Ⅱ .

测线Ⅱ 的断错特征与测线Ⅰ 相同, 除了在桩号1 855(断点F_1-2)处发生整体断错外, 在桩号2 460处存在断点F'_1-2。断点F_1-2 表现为向N倾的正断性质, 上断点埋深为238~242m。

3.3 测线Ⅲ 地震剖面特征

图 7给出了测线Ⅲ 的叠加时间剖面图。在剖面上可识别9个有效反射波组, 包括新近纪地层的5个反射波组T_N— $T_{N}^{5}$ 以及第四系的4个反射波组T_Q— $T_{Q}^{3}$ 。新近纪地层底界面的反射波T_N出现扭曲、变形, 表现出断错特征, 分析判断应该是断层错动所致。浅层地震剖面揭示的断点对应于图 7中的F_1-3, 其位置位于测线Ⅲ 的桩号760附近。可以看到, 该断点倾向N, 为上盘下降、下盘上升的正断层。根据叠加时间剖面特征, 第四系底界面的反射波T_Q出现错断及能量转变, 上断点埋深235~240m。该测线与石油剖面及测线Ⅰ 、 Ⅱ 共同具有新近纪内地层紊乱的特征; 不同的是, 在该测线的早新生代地层内未出现向N下倾加深的地震反射界面T_E, 可能是由于测线较短未能检测到, 但也不排除是断裂不同段具有不同的构造特征所致。

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	图 7 测线Ⅲ 地震反射波叠加时间剖面Fig. 7 Stack time section of seismic reflector in profile Ⅲ .

3.4 测线Ⅳ 地震剖面特征

图 8给出了测线Ⅳ 的叠加时间剖面图。在剖面上共可识别9个反射波组, 包括4个第四系(T_Q— $T_{Q}^{3}$ )及5个新近系(T_N— $T_{N}^{5}$ )波组。基岩顶面反射波T_N在桩号3 190处出现明显整体落差及强烈扭曲变形, 分析认为是断层错动所导致, 判断为F_1-4断点。图中F_1-4断点以北的新近系内波组紊乱, 尤其是 $T_{N}^{4}$ 波组的震相缺失较为明显。 8 420~9 695桩号段出现透镜体形状的反射波组, 由此判断存在F'_1-4断点, 其北侧也缺失 $T_{N}^{3}$ 及 $T_{N}^{2}$ 波组; 该断点的断错层位更浅, 活动性更强, 推测错断了埋深约291m的第四系底界面T_Q。 F'_1-4断点北侧的古近系内虽未出现类似于测线Ⅰ 和Ⅱ 的反射震相T_E, 但基岩顶面也呈现出向N下倾加深特征。

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	图 8 测线Ⅳ 地震反射波叠加时间剖面Fig. 8 Stack time section of seismic reflector in profile Ⅳ .

3.5 地震剖面综合分析

结合石油剖面资料对文中给出的4条浅地震叠加时间剖面进行总结分析, 可得到如下分析结果:

(1)石油剖面2005nh137d_s及85nh117.5均表现出犁式断层的形态特征, 但后者更具有控盆边界生长断层的识别标志和特点。综合分析认为前者控制了金坛-如皋断裂, 后者控制了栟茶河断裂, 剖面揭示了断裂的大体位置及最浅稳定标志层T_N。

(2)4条浅层地震勘探测线的断点两侧晚新生代地层底界面反射波T_N出现断错、位移现象, 反射波同相轴形态和特征发生突变, 断点均为倾向N的正断层性质。

(3)浅地震勘探测线Ⅰ 和Ⅱ 与石油剖面2005nh137d_s揭示的地层特征一致, 三者均显示基岩内部出现了T_E反射波, 该地震界面向N下倾加深; 而该特征在测线Ⅲ 上并未出现, 这可能是由于测线较短未能检测到, 但也不排除是由于断裂不同段具有不同的构造特征所致; 测线Ⅳ 上虽未出现类似于测线Ⅰ 和Ⅱ 的反射震相T_E, 但基岩顶面也呈现出向N下倾加深的特征。

(4)4条测线的叠加时间剖面均显示在新近纪地层内出现紊乱、不连续现象, 分析认为是火山岩在地震剖面上的反映, 综合判断, 金坛-如皋断裂北东段可能对新生代岩浆活动具有控制作用。

(5)在测线检测地段、有效探测深度范围内, 金坛-如皋断裂北东段并非单一的一条断层, 而是由2条N倾、 NEE走向的正断层组成的断裂带; 其南支断错层位更浅, 活动性更强。

根据石油剖面提供的目标断裂的空间位置及其深部形态、浅层地震剖面上的断点特征及其在平面的分布位置分析, 可以认为4条浅地震剖面揭示的断层应该是金坛-如皋断裂北东段。

4 断裂活动性的初步分析

通过前文对浅层地震叠加时间剖面揭示的断层特征和地层上断点埋深的分析可以看出, 4条地震剖面所揭示的金坛-如皋断裂北东段的上断点均位于235~243m的深度范围内。

测区 1:25万南通市幅区域地质调查报告及近期完成的江苏省 1:5万三仓镇、弶港镇、李堡镇、栟茶镇、岔河镇、白蒲镇幅区域地质调查报告(后文简称5万区调)显示^①(①张登明, 2003, 1:25万南通市幅区域地质调查报告。)^②(②刘宪光, 2016, 江苏省1:5万三仓镇、弶港镇、李堡镇、栟茶镇、岔河镇、白蒲镇幅区域地质调查报告。), 4条剖面经过地段的第四系厚度为285~310m。因此, 根据图 1中第四系底界面及各测线上断点埋深, 浅层地震剖面所揭示的断层上断点均延伸至早第四纪地层, 据此判断, 金坛-如皋断裂北东段应是第四纪以来的隐伏活动断裂。

在测线Ⅰ -1东、测线Ⅰ -2北东及测线Ⅳ 东分布了5万区调第四系基准孔和控制孔ZKA04、 BA01及ZKA1(位置见图1, 参数见表2), 综合利用其岩性特征、测年数据、孢粉组合和粒度特征等资料详细划分了第四系。这3个钻孔所确定的 $Q_{p}^{1}$ 底界面埋深分别为298.19m、 286.7m和312.4m; $Q_{p}^{2}$ 底界面埋深分别为179.75m、 182.16m和178.15m。由表1可见, 在4条浅地震剖面上的金坛-如皋断裂北东段的断点中, 断点埋深为235~243m, 即由地震叠加剖面可分辨的断层上断点深度均在 $Q_{p}^{1}$ 和 $Q_{p}^{2}$ 底界之间。综合分析认为, 金坛-如皋断裂北东段的活动时代可能为早更新世。

表2 钻孔深度与厚度数据 Table2 Parameters of depth and thickness of boreholes

地层单位	ZKA1孔深 /m	ZKA04孔深 /m	BA01孔深 /m	地层岩性描述
全新统如东组(Qhr)	23.79	23.79	24.1	灰色亚黏土、亚砂土夹粉砂或粉细砂
更新统滆湖组( $Q_{P}^{3}$ g)	90.8	90.91	91.17	中粗砂、粉细砂夹亚黏土亚砂土
更新统昆山组( $Q_{P}^{3}$ k)	100.44	101.86	98.0
更新统启东组( $Q_{P}^{2}$ q)	178.15	179.75	182.16	灰黄色亚黏土夹中粗砂、粉细砂
更新统海门组( $Q_{P}^{1}$ h)	312.4	298.19	286.7	下部以砂层为主, 含砾粗砂、细中砂、粉砂; 中上部以灰黄、棕黄色亚黏土为主

表2 钻孔深度与厚度数据 Table2 Parameters of depth and thickness of boreholes

5 总结与讨论

为调查金坛-如皋断裂北东段的空间位置、性质及其初步活动性, 本研究在石油地震反射剖面提供金坛-如皋断裂北东段的空间位置及反射标志层的基础上, 跨断裂收集和布设了4条浅层地震反射纵波测线, 通过高分辨率地震数据采集技术、不同吨位可控震源或炸药震源以及高精度的数据处理方法, 获得了金坛-如皋断裂北东段的空间位置、性质及其平面展布特征。此外, 结合5万区调中基准孔和控制孔的资料, 对断裂活动性进行了初步分析。

在本次测线控制地段、有效探测深度范围内, 金坛-如皋断裂北东段并非单一的一条断层, 而是由2条N倾、走向NEE的正断层组成的断裂带, 其控制了海安凹陷的南边界。 4条测线的叠加剖面显示, 断裂的南支断错的层位更浅, 活动性更强, 其上断点埋深235~243m, 断错了下更新统下部, 推测其最新活动时代为第四纪早更新世(Qh¹)。综合分析认为, 金坛-如皋断裂为海安凹陷和通扬隆起的边界断裂, 而栟茶河断裂是一条错断了隆坳构造边界断裂的断裂。本文的探测研究结果为进一步明确金坛-如皋断裂两侧的新生代地层厚度、认识该断裂的活动性提供了地震学依据, 可为城市地震危险性和危害性分析与评价提供极为重要的基础资料。

地震勘探方法虽具有探测深度大、分辨率高和探测结果可靠等优点, 但仅根据地震叠加剖面还不能够确定叠加剖面有效反射波组的地层属性和地层年代归属。因此, 在缺乏地层属性和年代学依据的情况下, 仅凭地震叠加剖面确定的断层上断点对目标断裂的活动性进行判断仍有所欠缺。为判定金坛-如皋断裂的活动性, 尤其是确定其最新活动时代, 需在地震勘探的基础上进行小间距的跨断层钻孔联合地质剖面探测、年代学测龄等工作。

致谢本项探测研究工作得到了江苏省地震局相关部门、海安市地震局、如东市地震局及如皋市地震局的大力支持与配合; 项目的实施过程中得到了中国石油大学陈书平教授的大力支持。在此一并表示感谢!

参考文献

文献列表

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2006

0.0

柴炽章, 孟广魁, 杜鹏, 等. 2006. 隐伏活动断层的多层次综合探测: 以银川隐伏活动断层为例[J]. 地震地质, 28(4): 536-546.

CHAI

Chi-zhang

, MENG

Guang-kui

, DU

Peng

, et al. 2006. Comprehensive multi-level exploration of buried active fault: An example of Yinchuan buried active fault[J]. Seismology and Geology, 28(4): 536-546(in Chinese).

Yinchuan Basin is a graben-like downfaulted Cenozoic era basin located on the west edge of Ordos Massif.Its activity is violent and deposition is very thick.Yinchuan City is located in the middle of Yinchuan Basin.The seismic petroleum exploration shows that a buried active fault lies in the east of Yinchuan City,named as the Yinchuan buried fault,which strikes NNE and dips west,with a total length of more than 80km.Because the seismic petroleum exploration did not gain any explained signals at the depth ranging from 0 to 400m,so whether the Yinchuan buried fault is active or not in the late Quaternary and its exact surface projective location hasn't been known yet.It has been a “worry” in the urban planning and development of Yinchuan for a long time.Under the financial support of the national and local governments,we launched the project entitled “The prospecting of active fault and earthquake risk assessment in Yinchuan City”.In order to facilitate the exploration,we selected Xinqushao village in the southeast suburb of Yinchuan City to be the site for the integrated test exploration of the Yinchuan buried fault before the exploration,based on the information obtained from the seismic petroleum exploration.Considering that the thick Quaternary sediment in Yinchuan reaches to 1609m,and that the depositional environment is the Yellow River flood plain and the lateral change of lithology is complex,we adopted in the test exploration the train of thoughts of “inferring an unknown fact from a known fact,and from deep to shallow and directly to the top”.The experimentation has been developed step by step according the working order of multilevel seismic exploration→composite geological profile drilling→trenching.Along the same measuring line at Xinqushao,first,we adopted the seismic reflection exploration of primary wave in three levels with the group interval of 10m→5m→1m to catch the master fault of the Yinchuan buried fault,and by tracing upward layer by layer in the order of the three exploration ranges,i.e.1400～400m→600～80m→150～20m,the position of the master fault at ±20m depth under the ground and its offset trace were primarily identified.And then,along the master fault and within the range of 100m at its both sides,9 boreholes of 20.5～100m were arranged for the composite geological profile drilling.The resulting information about the throws of the master fault was obtained,they are 20.34m,9.66m and 2.25m respectively at the depth of 43.75m,20.33m and 13.04m from the ground,and the buried depth of the upper offset point ≤8.34m.At the same time,using the intact core specimen from the fault plane of the borehole No.7,we calculated the dip angle of the fault as 71°at the depth of 55.27m and figured out the exact position of its extension to the earth's surface.Finally,a large-scale trial trench,which is 40 meters long,8～12 meters wide and 6 meters deep,was arranged across the master fault.The trenching revealed that the actual buried depth of the upper offset point of the master fault is 1.5m and there are seismic remains,such as offsets of 5 stages,sand liquefaction and surface rupture,etc.Among the 5 stages offsets,4 events occurred prior to 3170±80 a BP,belonging to the mid to late Holocene paleo-earthquakes.The age of the last event cannot be determined and it is inferred to be the result of the M 8.0 Yinchuan-Pingluo earthquake in 1737.In a word,through the comprehensive test exploration,we find that the Yinchuan buried fault is a Holocene active fault,which lays solid base for the next exploration.

1. Earthquake Administration of Ningxia Hui Autonomous Region, Yinchuan 750001, China; 2. Geophysical Exploration Center of China Earthquake Administration, Zhengzhou 450003, China

以银川活动断层试验探测为例,介绍了第四纪巨厚沉积区隐伏断层多手段、多层次探测的步骤与方法.在对前人资料综合分析的基础上,选择银川市兴庆区新渠梢村为综合探测试验场.首先,分层次布施道间距10m、5m和1m的浅层人工地震勘探,由深至浅将银川隐伏断层主断层逐步控制在可以布施浅钻勘探的程度.然后,实施钻孔联合剖面探测,确定了断层的准确位置和倾角,获得了由钻探资料可分辨的断层上断点埋深8.3m的信息.最后,通过大型探槽开挖,查明了断层实际上断点埋深1.5m和5期古地震活动事件.结合地层年龄的初步测定,得出了银川隐伏断层主断层中-晚全新世活动的结论.

... 柴炽章等, 2006 ...

2009

0.0

陈书平, 王小群, 王章青, 等. 2009. 海安凹陷上白垩统—新生界断裂形成及演化[J]. 石油地球物理勘探, 44(6): 760-766.

CHEN

Shu-ping

, WANG

Xiao-qun

, WANG

Zhang-qing

, et al. 2009. The fracture formation and its evolution from Upper Cretaceous to Cenozoic in Hai'an Depression[J]. Geophysical Prospcting for Petropleum, 44(6): 760-766(in Chinese).

根据近年来在海安凹陷获得的地震资料，对上白垩统—新生界内部断裂特征进行了研究。海安凹陷断层展布为北东向、北东东向和北西西或近东西向。主断层不同段走向不同，深浅层结构不同，控制凹陷结构；次级断层多受主断层控制，其形成和走向受主断层影响。断层活动表现出旋回性特点，控制着盆地结构的旋回性演化。断层展布反映泰州组—阜宁组沉积期间断层为北西—南东向的伸展作用，同时又表现出受右旋扭动的影响；三垛组沉积早期为伸展性断层发育时期，伸展方向为北西—南东向；三垛组沉积晚期，受近东西向挤压，一些断层表现出走滑特点；新近纪早期，断裂继承性活动，晚期主要沿主断裂活动。这种构造应力场的变化与板块运动的改变有关。

... 陈书平等, 2009 ...

... 冉怀江等, 2012)在海安凹陷盆地内进行的大量地震勘探工作表明, 金坛-如皋断裂对盆地的隆坳格局具有控制作用, 其经历了复杂的演化过程(陈书平等, 2009) ...

... 由图可见, 栟茶河断裂北侧新生界内存在3个明显的角度不整合界面(图 3中的 TE1、 TE3及T_N), TE1为泰州组与下伏地层反射界面, TE3为阜二段与下伏地层反射界面, T_N为盐城组与下伏地层反射界面, 分别代表了仪征运动、吴堡运动及三垛运动(陈书平等, 2009) ...

2007

0.0

邓起东, 卢造勋, 杨主恩. 2007. 城市活断层探测和断层活动性评价问题[J]. 地震地质, 29(2): 189-200.

DENG

Qi-dong

, LU

Zao-xun

, YANG

Zhu-en

. 2007. Remarks on urban active faults exploration and associated activity assessment[J]. Seismology and Geology, 29(2): 189-200(in Chinese).

According to the practice of urban active fault exploration and associated activity assessment conducted in recent years,this paper summarizes the problems encountered in geological,geomorphological,geochemical and geophysical explorations,and proposes the following means and suggestions to solve these problems.To determine the most recent faults or fault zones,emphases should be placed on iden～tifing the youngest active faults and offset geomorphology.To understand the history of faulting and to discover the last offset event,it is suggested to combine geophysical prospecting,drilling and trenching into one profile.Because of significant uncertainties in late Quaternary dating,it is advised to sample systematically and to use multiple dating methods.Shallow seismic reflection has been proven to be the most useful method in urban active fault exploration.However,it is a pressing need to increase the quality of data acquiring and data processing to obtain high resolution images,so that the abi～lity of identifying active faults could be enhanced.Combination of seismic P-wave reflection and S-wave reflection methods is proved to be a powerful means to investigate tectonic environments of deep crust.

1. Institute of Geology, China Earthquake Administration, Beijing 100029, China; 2. Earthquake Administration of Liaoning Province, Shenyang 110034, China

根据近年来城市活动断层探测与地震危险性评价的实际工作,归纳了探测工作中在地质地貌、地球化学和地球物理探测中存在的问题,针对性提出了相应的建议,以进一步推进这一工作。

... 邓起东等, 2007 ...

2002

0.0

方盛明, 张先康, 刘保金, 等. 2002. 大城市活断层探测的地球物理方法[J]. 地震地质, 24(4): 606-613.

FANG

Sheng-ming

, ZHANG

Xian-kang

, LIU

Bao-jin

, et al. 2002. Geophysical methods of the exploration of active faults in urban areas[J]. Seismology and Geology, 24(4): 606-613(in Chinese).

This paper gives a brief account of the significance of urban active fault exploration and presents a general review of active fault exploration around the world. Earthquakes provoked by active faults directly beneath the metropolises can cause serious disasters to the cities. If urban active faults are precisely determined and effective precautions are taken, losses at the time of earthquake occurrence can be greatly reduced. We elaborate on various kinds of possible geophysical methods for seismic active fault exploration and their main features. We also discuss the scope of application of related geophysical methods and the major problems that they can solve in the different periods of active fault exploration, such as regional survey or preliminary investigation, detailed exploration or precise location, and the identification of seismogenic structures.

1. Research Center of Exploration Geophysics, China Seismological Bureau, Zhengzhou 450002, China; 2. Institute of Geology, China Seismological Bureau, Beijing 100029, China

简要地介绍了开展大城市地震活断层探测的意义及世界各国开展活断层探测的基本情况.城市及邻近地区地震活断层引起的直下型地震,将会给大城市造成巨大的地震灾害.准确地探测出大城市的活断层分布,采取有效措施,可大大降低地震时的损失.文中重点介绍了开展地震活断层探测的地球物理方法的类型和主要特点,在区域探查与初步鉴定阶段、详细探测与精确定位阶段、孕震构造探测阶段可能涉及到的各种地球物理探测方法、适用范围及所能解决的主要问题.

... 2 浅层反射地震勘探方法浅层地震反射勘探是厚覆盖区断裂探测最常用、最有效的方法之一, 该方法具有探测深度大、分辨率高及结果可靠等优点, 已经得到了广泛应用(方盛明等, 2002 ...

2013

0.0

顾勤平, 康清清, 许汉刚, 等. 2013. 薄覆盖层地区隐伏断层及其上断点探测的地震方法技术: 以废黄河断层为例[J]. 地球物理学报, 56(5): 1609-1618.

Qin-ping

, KANG

Qing-qing

, XU

Han-gang

, et al. 2013. Seismic exploration methods for buried faults and its up-breakpoint in thin sediment areas: An example of the Feihuanghe Fault[J]. Chinese Journal of Geophysics, 56(5): 1609-1618(in Chinese).

We have obtained the exact location and depth of up-breakpoint and velocity distribution image of the Feihuanghe fault in the line control by joint inversion of seismic exploration methods(common offset seismic reflection, shear wave reflection and high-resolution refraction) on the same line. The results indicate that in fault investigations for thin Quaternary sediments, the joint inversion of the above three technical methods is not only more reliable than using any one of them alone to identify the location, nature and characteristics of faults by different means, but also provides seismological evidence for the position layout of composite drilling sections and the depth designing of drilling. According to the confirmation of high-precision composite drilling geological sections, the main stratigraphic interfaces and tectonic features obtained from the three kinds of seismic exploration methods are quite consistent with the results from the composite drilling geological section. The experimental results show the feasibility of the joint inversion of the above three kinds of seismic exploration methods in thin Quaternary sediments and the efficiency of the combination of seismic exploration and composite drilling geological profiles.

Gu Qin-Ping 1 ;Kang Qing-Qing 1 ;Xu Han-Gang 1 ;Liu Jian-Da 1 ;Li Da-Hu 2 ;Nie Bi-Bo 3 ;

通过在同一条测线上应用三种不同地震勘探手段(共偏移距地震反射法、横波反射法与高分辨率折射法)联合反演的方法,获得了测线控制地段内废黄河断层的确切位置、上断点埋深以及速度分布图像.探测结果表明:在薄覆盖层地区的断裂调查中,上述三种技术手段的联合反演要比单独使用其中任何一种手段更加可靠,并能从不同角度查明断层的位置、性质及其特征,为钻孔联合剖面位置的布设和钻孔深度的设计提供地震学依据.经高精度钻孔联合地质剖面证实,三种地震勘探方法反演得到的主要地层界面和构造特征都与钻孔联合地质剖面吻合较好.试验表明了上述三种地震勘探方法在基岩面埋深较浅地区联合反演的可行性以及地震勘探与钻孔联合地质剖面相结合的工作方法的有效性.

... 顾勤平等, 2013, 2015 ...

2015

0.0

顾勤平, 许汉刚, 赵启光. 2015. 厚覆盖层地区隐伏活断层探测的地震方法技术: 以桥北镇—宿迁断层为例[J]. 物探与化探, 39(2): 408-415.

Qin-ping

, XU

Han-gang

, ZHAO

Qi-guang

. 2015. The seismic exploration method for buried active fault in thick sediment area: A case study of Qiaobei-Suqian Fault[J]. Geophysical and Geochemical Exploration, 39(2): 408-415(in Chinese).

Seismic reflection exploration is the main technique in present urban active faults detecting.The effect of investigating fault and its up-breakpoint in thick Quaternary sediments depends on the working methods and technical parameters.Qiaobei-Suqian fault is an important buried fault along Tan-Lu fault zone in Jiangsu. In this paper,based on QL14 line laid on the fault in thick sediments during the active fault survey in Suqian City and aimed at investigating the spatial distribution,characteristics and activities of the fault controlled by the line,the authors used different seismic exploration methods and acquisition parameters to perform a high-resolution seismic reflection experiment and obtain the imaging of buried fault in the light of the work thinking of combination and fractional steps and according to different targets,the depth of the target layer and the accuracy requirement.The technique solved the contradiction between the field data acquisition and the geological task.The authors obtained high-resolution images of structures in the depths of 16~450 m after data processing,and the prospecting results provide seismological evidence for the position layout of composite drilling sections,the depth designing of drilling and the evaluation of fault activity.The high-precision composite drilling geological sections show that the main stratigraphic boundaries and tectonic features obtained from the seismic exploration methods are quite consistent with the results from the composite drilling geological section.The experimental result shows that the combined detection methods can receive the attitude and distribution of the fault in different depths and the complete distribution image from the depth to the shallow part of the fault.The feasibility of the seismic exploration methods for locating the buried fault and determining its activity in thick Quaternary sediments and the efficiency of the combination of seismic exploration and composite drilling geological profiles are also demonstrated in this study.

1. Institute of Geophysics, China Earthquake Administration, Beijing 100081, China; 2. Earthquake Administration of Jiangsu Province, Nanjing 210014, China

地震反射勘探法是当前城市地震活断层探测的主要方法,它在厚覆盖区探测断层及其上断点的效果取决于所采用的工作方法和技术参数。桥北镇—宿迁断裂是郯庐断裂带在江苏境内一条重要的隐伏断裂。以宿迁市活动断层探测项目中针对该断裂敷设于厚覆盖层地区的QL14测线为例,为了查明测线控制地段内断裂的空间展布形态、性质以及活动性,针对不同目标、目的层深度和精度要求,作者按照组合、分步探测的工作思路,采用了不同的地震勘探方法技术和采集参数对其进行了高分辨率地震反射成像,解决了地质任务要求与野外资料采集方法之间的矛盾,从而获得了埋深约16~450 m范围内高分辨率的地层结构和非常清晰的断裂构造图像,为钻孔联合剖面位置的布设、钻孔深度的设计以及断裂活动性的评价提供了地震学依据。最后经高精度钻孔联合地质剖面证实,地震勘探方法反演得到的主要地层界面和构造特征都与钻孔联合地质剖面吻合较好。试验结果表明:采用组合探测的方法能够获得断层在不同深度的产状、展布以及由深至浅完整的分布图像;地震勘探法在厚覆盖区确定隐伏断层具体位置和判定断层活动性具有可行性以及地震勘探与钻孔联合地质剖面相结合的工作方法具有有效性。

... 顾勤平等, 2013, 2015 ...

2007

0.0

何正勤, 陈宇坤, 叶太兰, 等. 2007. 浅层地震勘探在沿海地区隐伏断层探测中的应用[J]. 地震地质, 29(2): 363-371.

Zheng-qin

, CHEN

Yu-kun

, YE

Tai-lan

, et al. 2007. Application of shallow seismic exploration in detection of buried fault in coastal areas[J]. Seismology and Geology, 29(2): 363-371(in Chinese).

The depth of Quaternary in China coastal zone varies greatly.In most areas,silt,clay and sand are always multiply interbedded.This kind of formation can attenuate greatly the high frequency signal,and is unfavorable to propagation of seismic wave.At the same time,the density of population in the area is much higher and the industrial noise is strong,so the trigger and receiver conditions are not ideal.The paper presents some application examples of detecting buried faults with near-surface seismic methods in east Guangdong,Tianjin and Tangshan where the thickness of overburden varies greatly,and systemically introduces the methods of fieldworks,data processing and explanation approaches.It also illustrates the effective methods of how to improve SNR and resolution in environment with strong noise.In the application,the signal of refection is strong and the buried faults can be reflected evidently.Proofs of drilling at both sides of the faults approve that the depth of interface,location of fault point and throw of basement determined by seismic exploration are all reliable.The techniques and methods mentioned in this paper are of important reference value in urban active fault detection and engineering geophysical prospecting in similar areas.

1. Institute of Geophysics, CEA, Beijing 100081, China; 2. Earthquake Administration of Tianjin, Tianjin 300201, China

中国沿海地区的第四系厚度变化较大,在大部分地区存在淤泥、黏土和砂层的多重互层情况,这种地层结构对地震波的传播十分不利,容易造成对高频信号能量的强烈耗散。沿海地区又具有人口密度大、工业干扰强烈的特点,地震波的激发、接收条件较差。文中给出了在粤东、天津和唐山覆盖层厚度变化较大的地区,利用浅层地震勘探开展隐伏断层探测的应用实例。较系统地介绍了野外工作、资料处理和解释方法。阐述了在强干扰环境下提高信噪比和分辨率的有效技术途径。所给实例中的反射波组能量强,隐伏断层的反应明显,经跨断点钻探验证,结果证实地震勘探确定的界面深度、断点位置和基岩错距等参数都是可靠的。所述技术方法对类似地区的城市活断层探测和工程物探工作都有较重要的参考价值。

... 何正勤等, 2007, 2010 ...

... 采集设备的性能良好是获得可靠结果的重要因素(何正勤等, 2007) ...

2010

0.0

何正勤, 潘华, 胡刚, 等. 2010. 核电厂址隐伏断裂探测中的地震勘探方法研究[J]. 地球物理学报, 53(2): 326-334.

Zheng-qin

, PAN

Hua

, HU

Gang

, et al. 2010. Study on the seismic exploration method to detect buried fault in the site of nuclear power plant[J]. Chinese Journal of Geophysics, 53(2): 326-334(in Chinese).

The work experience of shallow seismic exploration in land and water areas for earthquake safety evaluation of nuclear power sites is reviewed in this paper. By analyzing different typical engineering cases, some key technical issues, to which more attention should be paid in the buried fault detection, are discussed for different geological and geophysical conditions. For different geological conditions some critical schemes to implement the seismic exploration are presented, such as equipment selection, layout design, quantitative parameters optimization and the method to identify the fault. This study provides a practical and technical guide for detection of capable fault in nuclear power sites with similar geological conditions.

Institute of Geophysics, China Earthquake Administration, Beijing 100081,China

总结了近年来在多个核电厂址地震安全性评价中陆域覆盖区和海域浅层地震勘探的工作经验，通过对不同的典型工程实例分析，讨论了在不同地质和地球物理条件下，用浅层地震反射法探测隐伏断裂时应注意的关键性技术问题.提出了在不同地质条件下实施隐伏断裂探测时的地震仪器设备选择、方案设计、参数选取、断层识别的基本方法.本文的研究成果可为类似地区开展核电厂址能动断层探查工作提供实用性的技术资料.

... 何正勤等, 2007, 2010 ...

2008

0.0

刘保金, 柴炽章, 酆少英, 等. 2008. 第四纪沉积区断层及其上断点探测的地震方法技术: 以银川隐伏活动断层为例[J]. 地球物理学报, 51(5): 1475-1483.

LIU

Bao-jin

, CHAI

Chi-zhang

, FENG

Shao-ying

, et al. 2008. Seismic exploration method for buried fault and its up breakpoint in Quaternary sediment area: An example of Yinchuan buried active fault[J]. Chinese Journal of Geophysics, 51(5): 1475-1483(in Chinese).

Seismic exploration is an effective geophysical method for buried fault survey. The spread geometries of seismic exploration are the main factors to affect the exploration results as well as the accuracy of fault location. In this paper, based on the shallow seismic exploration data obtained from active fault survey in Yinchuan city and also in combination with the oil seismic exploration profiles along with the drilling geological data, an upward fault tracing method was proposed to determine the geometry of the target fault and its up-breakpoint in thick Quaternary sediments. The result shows that the combination of high resolution shallow seismic exploration and drilling geological section is an effective way for locating the buried fault and determining its activity.

1 Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China 2 Geophysical Prospecting Center, China Earthquake Administration, Zhengzhou 450002, China 3 Earthquake Administration of Ningxia Hui Autonomous Region, Yinchuan 750001, China

地震勘探方法是隐伏断层探测的一种有效的地球物理探测手段，而地震勘探的探测参数是影响探测效果和断层定位精度的主要因素.本文以银川市活断层探测的浅层地震勘探资料为例，并结合石油地震勘探剖面结果和钻孔地质资料，阐述了在第四纪覆盖层较厚的地区，由深至浅追踪目标断层形态和确定断层上断点空间位置的方法技术.结果表明，采用高分辨率地震勘探和钻孔地质剖面相结合的探测方法是确定隐伏断层位置、判定断层活动性的有效方法.

... 刘保金等, 2008 ...

2006

0.0

... 2 石油剖面自20世纪50年代以来, 众多研究者(邱海峻等, 2006 ...

2012

0.0

冉怀江, 司宝玲, 陈方鸿, 等. 2012. 海安凹陷古近系沉积层序及对油气藏的控制[J]. 石油地球物理勘探, 47(5): 795-802.

RAN

Huai-jiang

, SI

Bao-ling

, CHEN

Fang-hong

, et al. 2012. Sedimentary sequences in Hai'an Depression and control on reservoir of the Paleocene[J]. Oil Geophysical Prospecting, 47(5): 795-802(in Chinese).

通过岩心、测井、地震以及分析化验等资料,本文对苏北盆地海安凹陷古近系进行了层序地层分析以及沉积相识别,进而研究了层序沉积体系的分布配置关系，揭示了主要油气藏分布规律。研究认为，从古近系泰州组到三垛组的盆地断陷阶段，海安凹陷经历了仪征、吴堡、真武和三垛等四次较大的构造抬升运动，形成了3个二级层序，在二级层序格架内可分为7个三级层序、17个体系域，其中主要的含油体系域包括SQ1-1低位体系域、SQ1-2低位体系域、SQ1-3高位体系域、SQ2-1湖侵体系域及SQ3-1低位体系域等；主要含油体系域发育的沉积相类型主要有扇三角洲、河流三角洲、辫状河三角洲以及湖相等；层序地层格架内体系域的沉积特征及空间位置的差异形成了不同的有利生储盖配置：SQ1-1低位体系域生储盖组合、SQ1-2低位体系域生储盖组合、SQ1-3高位体系域生储盖组合、SQ2-1湖侵体系域生储盖组合、SQ3-1低位体系域生储盖组合等。

1994

0.0

... 浅层地震勘探能否取得好的效果取决于原始数据质量的好坏, 想要通过数据处理从丢失有效信息的地震资料中获得有用的结果往往是徒劳的(伊尔马滋, 1994) ...

2016

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许汉刚, 范小平, 冉勇康, 等. 2016. 郯庐断裂带宿迁段F₅断裂浅层地震勘探新证据[J]. 地震地质, 38(1): 31-43. doi: 103969/j. issn. 0253-4967. 2016. 01. 003.

Han-gang

, FAN

Xiao-ping

, RAN

Yong-kang

, et al. 2016. New evidence of the Holocene fault in Suqian segment of the Tanlu fault zone discovered by shallow seismic exploration method[J]. Seismology and Geology, 38(1): 31-43(in Chinese).

The fault F 5 is considered as the most active fault in the Tanlu fault zone(Yi-Shu fault zone), which is located from Weifang of Shandong Province to Jiashan of Anhui Province, with a length of 360km. It has always been a focus of concern to many geoscientists because of its complexity and importance. But, for a long period of time, there exists biggish indetermination in the accurate position and active ages of the fault F 5 in Suqian section of Tanlu fault zone. Seismic reflection exploration is the main technique in present urban active faults detecting. In order to investigate the spatial distribution, characteristics and activities of the fault F 5 in covered terrains, we carried out a systematic survey to the fault with shallow seismic prospecting method and obtained the accurate position and development characteristics of the fault. The results show that the fault F 5 continues to develop toward south rather than ending at the Huancheng South Road of Suqian City. F 5 is mainly composed of two main faults, which dip in opposite directions and almost vertically. Near the Sankeshu town, F 5 is composed of three faults with right-stepping, forming a small pull-apart basin with length of 6km, width of 2.5km, controlling the deposition of Neogene and Quaternary strata. By combining the results of composite drilling section and trenching, we make a conclusion that the western branch of fault F 5 is a Holocene active fault, and the eastern branch is a Pleistocene active fault. Our general view is that fault F 5 is a Holocene active fault.

1. Earthquake Administration of Jiangsu Province, Nanjing 210014, China; 2. Institute of Geology, China Earthquake Administration, Beijing 10029, China

郯庐断裂带沂沭段最新活动的断层一般称之为F 5 断层,分布于潍坊至嘉山一带,长约360km。郯庐断裂带宿迁段F 5 断裂的准确位置、活动时代一直以来存在较大的不确定性。文中通过浅层地震勘探对F 5 断裂进行了系统性勘探,获取了准确的定位及其断裂发育特征。结果表明,F 5 断裂并未终止于原来认定的宿迁市环城南路处,而是继续向南延伸; F 5 断裂主要由2条相向而倾、近直立发育的主干断裂组成;在三棵树乡附近,F 5 断裂由3条断裂组成,且呈右阶排列,阶区长度约6km,宽度约2.5km,形成小的拉分盆地,控制了新近纪以来地层的沉积。结合钻孔联合剖面和槽探结果,判断F 5 断裂西边界断裂为全新世活动断裂,东边界断裂为晚更新世活动断裂,总体认为F 5 断裂为全新世活动断裂。

... 许汉刚等, 2016) ...

2005

0.0

... 综上所述, 本次探测工作所采用的4~6m道间距观测系统既能满足基岩面的追踪需求, 又可用来捕捉判定目标断裂是否属于地震活动断层的晚更新世地层底界面(中国地震局, 2005) ...

2016

0.0

... 左丽琼等(2016)为寻找地热资源在金坛-如皋断裂北东段选取了7个微动测深点进行研究, 虽获取了各地层S波的速度结构特征, 但因测点间点距、断层平面位置误差较大, 最大有效探测深度约3 000m, 且对晚新生代地层的分辨仍然不够精细, 不足以对其位置、性质及最新活动时代进行评价 ...