利用地貌形态估算西秦岭-松潘构造结及邻区的下地壳黏滞系数

引用本文

魏聪敏, 葛伟鹏, 张波. 利用地貌形态估算西秦岭-松潘构造结及邻区的下地壳黏滞系数[J]. 地震地质, 2020,42(1): 163-181.
WEI Cong-min, GE Wei-peng, ZHANG Bo. ESTIMATING THE LOWER CRUSTAL VISCOSITY OF THE WESTERN QINLING-SONGPAN TECTONIC NODE AND ITS ADJACENT AREAS BY USING LANDFORM MORPHOLOGY[J]. SEISMOLOGY AND GEOLOGY, 2020,42(1): 163-181. 复制到剪切板

DOI:10.3969/j.issn.0253-4967.2020.01.011
Permissions

《地震地质》编辑部所有

利用地貌形态估算西秦岭-松潘构造结及邻区的下地壳黏滞系数

魏聪敏¹⁾, 葛伟鹏^1,^2),^*, 张波^1,²⁾

1) 中国地震局兰州地震研究所, 兰州 730000

2) 兰州地球物理国家野外科学观测研究站, 兰州 730000

*通讯作者: 葛伟鹏, 男, 1981年生, 副研究员, E-mail: geweipeng@gmail.com。

〔作者简介〕魏聪敏, 女, 1994年生, 现为中国地震局兰州地震研究所固体地球物理学专业在读硕士研究生, 研究方向为GPS地壳形变观测, 电话: 13051467088, E-mail: 15554186885@163.com。

收稿日期: 2019-04-12

基金项目: 中国地震局科技星火计划项目(XH18048)、国家重点研发计划项目(2017YFC1500102)、甘肃省自然科学基金(17JR5RA340)、中国地震局地震预测研究所基本科研业务专项(2014IESLZ05)和国家自然科学基金(41304035, 41572197, 41802228)共同资助

摘要

西秦岭-松潘构造结下地壳黏滞系数的定量化研究是理解青藏高原东缘及东北缘动力过程的基础。为进一步认识该区域岩石圈动力学的演化过程, 建立下地壳流与不同时间尺度岩石圈变形特征的相互联系, 文中以下地壳管道流模型为基础, 利用地貌形态估算下地壳的黏滞系数, 探讨深部岩石圈流变学过程如何作用于上地壳形变和构造地貌特征; 同时结合GPS速度场分析现今的地壳形变, 进一步研究区域弥散构造变形过程。结果表明: 1)若尔盖-红原盆地北侧及东北侧下地壳的黏滞系数小于东侧及东南侧; 2)下地壳流具有向NE低黏滞系数区流动的趋势, 较好地解释了该区域的造山运动过程、弧形等高线分布及“V”形展布断裂的发育; 3)GPS数据揭示的现今地表运动方向与黏滞系数反演的下地壳历史演化方向一致, 说明下地壳与上地壳可能具有良好的耦合特征。研究结果最终为解释不同走向和性质的断裂系发育、造山带形成、宏观地貌发育特征以及深入探讨青藏高原东北缘岩石圈的流变学和隆升动力学提供了依据。

关键词: 西秦岭-松潘构造结; 下地壳黏滞系数; GPS速度场; 构造地貌

中图分类号:P315.2 文献标志码:A 文章编号:0253-4967(2020)01-0163-19

ESTIMATING THE LOWER CRUSTAL VISCOSITY OF THE WESTERN QINLING-SONGPAN TECTONIC NODE AND ITS ADJACENT AREAS BY USING LANDFORM MORPHOLOGY

WEI Cong-min¹⁾, GE Wei-peng^1,²⁾, ZHANG Bo^1,²⁾

1) Lanzhou Institute of Seismology, China Earthquake Administration, Lanzhou 730000, China

2) Lanzhou National Geophysical Observation and Research Station, Lanzhou 730000, China

Abstract

The western Qinling-Songpan tectonic node is located at the intersection of three major tectonic units of Tibetan plateau, the South China Block and the Ordos Block, and is at the forefront of the northeastern margin of Tibetan plateau. It has unique geological and dynamic characteristics from the surface to the deep underground. Based on the model for ductile flow in the lower crust, the geomorphological form is used to estimate the viscosity of the lower crust, and how the rheological process of the deep lithosphere acts on the upper crust deformation and structural geomorphology. And combined with GPS velocity field data, the current crustal deformation is analyzed to further study the regional dispersive deformation process. The results show that the viscosity of the north and northeast of the Zoige-Hongyuan Basin is smaller than that of the east and southeast. Therefore, the lower crust flow has a tendency of flowing to the northeastern low viscosity zone. We believe that when the lower crust flows from the central plain of the Qinghai-Tibet Plateau to the rigid Sichuan Basin with a higher viscosity of the lower crust, it cannot flow into the basin, and part of the lower crust flow accumulate here, causing the upper crust to rise, and the uplifting led to the formation of the Longmen Mountains and a series of NNE-striking faults as well. When the lower crust flows to the northeast direction with a low viscosity, the brittle upper crust is driven together. Because of the remote effects from the Ordos Basin and the Longxi Basin, the mountains in this region are built slowly and the stepped arc-shaped topography of the current 3 000-meter contour line and the 2 000-meter contour line are developed. At the same time, a series of NWW-trending left-lateral strike-slip faults are developed. This explains the seismogenic tectonic model of the western Qinling-Songpan tectonic node as from NWW-trending left-lateral strike-slip faulting to the NNE-trending right-lateral strike-slip faulting and both having a thrust component. The current crustal movement direction revealed by the GPS velocity field is consistent with the direction of historical crust evolution of the lower crust revealed by the viscosity, implying that there is a good coupling relationship between the lower crust and upper crust. The results provide a basis for studying the development of fault systems with different strikes and properties, the formation of orogenic belts, the macroscopic geomorphological evolution characteristics, and the rheological and uplift dynamics of the lithosphere in the northeastern margin of the Tibetan plateau.
In addition, our research differs from the previous studies in the spatial and temporal scale. Previous studies included either the entire Qinghai-Tibet Plateau or only the eastern margin of the Qinghai-Tibet Plateau. However, our analysis on the contours and topographical differences in the topography of the western Qinling-Songpan tectonic knot reveals that the study area is controlled by the lower crust flow. Our results are confirmed by various observations such as seismology, magnetotellurics and geophysical exploration. Moreover, the previous studies did not point out enough that the elevation contours are elliptical, and the elliptical geomorphology further illustrates that the formation and evolution of the Qinghai-Tibet Plateau has rheological characteristics and also conforms to the continuous deformation mode. Meanwhile, in terms of time scale, the evolution time of the study area is divided into three types of simulation time according to geochronology. And the GPS velocity field is introduced to observe the present-day crustal deformation.

Keyword: western Qinling-Songpan tectonic node; lower crustal viscosity; GPS velocity field; tectonogeomorphology

文章图片

0 引言

20世纪80年代以来, 大量研究者给出了青藏高原不同的变形模式, 主要有刚性块体模型(Tapponnier et al., 1976, 1982; Avouac et al., 1993)、连续变形模型(England et al., 1982, 1985, 1986; Houseman et al., 1986)与地壳流模型(Bird, 1991; Royden et al., 1997; Clark et al., 2000)等。同时, 许多研究人员通过岩石力学实验预测中地壳或下地壳可能存在弱黏性区, 将其与脆性的上地壳分开(Goetze et al., 1979; Brace et al., 1980; Kirby, 1983), 并且许多地球物理学观测结果也表明地壳存在黏滞性(Jin et al., 1994; Makovsky et al., 1996; Nelson et al., 1996), 因此下地壳弱黏性层能够在地质时间尺度上流动(Block et al., 1990; Bird, 1991; Kruse et al., 1991; Wdowinski et al., 1992)。

青藏高原东北缘地区是否存在下地壳流一直存在争议。虽然青藏高原东北部(特别是西秦岭-松潘构造结附近)与喜马拉雅山脉不同, 其没有足够的结构、变质、温度测量和地质年代学数据等下地壳流模型的证据(Searle, 2015), 但在地震学领域, 无论是利用接收函数方法(Liu et al., 2015)、环境噪声层析成像(Yang et al., 2010), 还是利用区域地震衰减层析成像(Bao et al., 2011)进行分析, 结果均证明青藏高原东北部存在中下地壳流(潘佳铁等, 2017)。另外, 利用地球物理学方法, 例如建立二维黏弹塑性有限元模型(尹力等, 2018)以及地壳三维密度图像分析(杨文采等, 2017)等, 其结果也支持青藏高原下地壳物质流动已到达青藏高原东北缘的假说。

近年来, 以Poiseuille流和Couette流模型为基础的下地壳流动模型是青藏高原变形数值模拟的研究热点。下地壳流变学在控制地壳形变方面发挥着重要作用, 估算下地壳的流变参数可以探索构造变形与地形之间的关系(Clark et al., 2000)。黏滞系数是反映地球介质流变特性的重要参数之一(王庆良等, 1997), 前人已对青藏高原岩石圈下地壳的黏滞系数进行了反演与估计, 并开展了系统性的研究与分析。目前, 估算黏滞系数主要有2种方法: 1)通过GPS及InSAR等大地测量方法观测震后形变以求得黏滞系数(Ryder et al., 2007, 2010, 2011; Diao et al., 2018); 2)通过地形地貌解析方法, 以物理学概念中的流体力学理论获得黏滞系数(Clark et al., 2000)。

西秦岭-松潘构造结位于青藏高原东北部, 研究其周缘的黏滞系数可为该区域下地壳流模型提供重要的参数和依据, 以便进而分析青藏高原东北缘的造山机制等。在西秦岭-松潘构造结南部发生2008年汶川M_S8.0地震及2017年九寨沟M_S7.0地震后, 国内研究者开始对2次地震的震后形变过程开展深部流变学参数研究(Diao et al., 2018); 而历史文献记载西秦岭-松潘构造结北部, 即西秦岭北缘断裂以南的甘东南毗邻地区发生过多次破坏性地震, 包括离逝时间约2 200a的186BC甘肃武都7~7 1/4级地震(袁道阳等, 2007a)、离逝时间> 130a的1879AD武都南8级大地震(顾功叙, 1983; 冯希杰等, 2005; 侯康明等, 2005)等。由于该区无有效大地测量等地壳震后形变数据, 很难通过震后形变研究方法对下地壳黏滞系数进行有效约束。

因此, 本文以下地壳管道流模型为基础, 采用地貌解析方法估算西秦岭-松潘构造结及邻区的下地壳黏滞系数, 从而推断下地壳流流动的优势方向, 并进一步讨论深部岩石圈流变学过程。同时, 利用GPS速度场分析该区域的地表变形和弥散构造变形, 进而对比分析地表与深部研究结果, 探讨深部岩石圈流变与地表变形、构造地貌演化的匹配关系。

1 区域概况

新生代以来, 印度板块向欧亚板块俯冲碰撞导致青藏高原快速隆升、高原周边强烈变形, 形成现今高原内部和周边的地貌格局(Molnar et al., 1975)。西秦岭-松潘构造结(图 1)位于青藏高原、华南地块、鄂尔多斯地块三大构造单元的交会地带, 又处于青藏高原东北缘扩展的前缘部位, 属于地壳尺度上的巨型构造结, 总体呈倒三角形, 具有独特的从地表到深部的地质与动力学特征(张国伟等, 2004)。该区地质构造背景复杂, 在印支期以来大量先存构造的基础上, 北侧的西秦岭地区主要发育NW向和NE向2组活动断裂, 组成独特的“ V” 字弧形构造(袁道阳等, 2004; 郑文俊等, 2016; 张波等, 2018); 南侧主要发育了东昆仑尾端帚状散开的弧形构造系, 包括龙日坝断裂、岷江断裂和虎牙断裂等(Ren et al., 2013)。断裂的几何展布情况也充分体现了青藏高原向外扩展时与华南块体和鄂尔多斯块体的相互作用。区域内构造活动强烈, 是南北地震带北段8级大地震最集中的区域, 地震灾害严重(张培震等, 2013)。历史上发生过多次7级以上大地震, 如1654年天水南8级地震(韩竹军等, 2001; 杨晓平等, 2015)、 1879年武都南8级地震(顾功叙, 1983; 侯康明等, 2005; 冯希杰等, 2005)、 2008年汶川M_S8.0地震(张培震等, 2009; Zhang, 2013)、 186BC武都7~71/4级地震(袁道阳等, 2007a)、 1976年松潘7.2级地震、 1933年叠溪7.5级地震(Ren et al., 2018)等。因此, 结合活动断裂运动特征和震源机制解, 同时利用GPS速度场分析西秦岭-松潘构造结及其邻区现今的地壳形变机制, 可进一步研究区域弥散构造变形过程。

Figure Option
View Download New Window

图 1 西秦岭-松潘构造结的活动断裂与历史地震分布图
F₁西秦岭北缘断裂; F₂临潭-宕昌断裂; F₃迭山-光盖山断裂; F₄迭部-白龙江断裂; F₅塔藏断裂; F₆岷江断裂; F₇龙日坝断裂; F₈哈南-稻畦子断裂; F₉武都-康县-略阳断裂; F₁₀两当-江洛断裂; F₁₁日月山断裂; F₁₂鄂拉山断裂Fig. 1 Distribution of active faults and historical earthquakes in the western Qinling-Songpan continental tectonic node.

西秦岭-松潘构造结既是高原边缘的构造交会区, 也是地形地貌的过渡区。构造结北部的西秦岭为青藏高原向黄土高原的过渡区, 构造结东南侧的龙门山为青藏高原向四川盆地的过渡区。过渡区地形起伏度极大, 山大沟深, 发育有白龙江、白水江、涪江、岷江和洮河等大型河流。地貌被严重地侵蚀破坏, 例如仅美武高原保留较完整的一块主夷平面, 武都地区残留多级岩溶夷平面(陈洪凯等, 1997; 潘保田等, 2002)。差异地貌明显, 多以深大断裂为边界, 例如西秦岭北缘断裂为西秦岭和陇西盆地的宏观地貌边界, 龙门山断裂、虎牙断裂为松潘构造结与四川盆地的边界(Chen et al., 1994; Tian et al., 2018)。基于下地壳流模型对构造结复杂的地形地貌进行解析, 可研究松潘-西秦岭构造结及邻区的下地壳黏滞系数, 结合GPS速度场, 综合讨论深部岩石圈流变学过程。

2 方法

本文采用地形地貌解析方法, 使用SRTM地形数据估算西秦岭-松潘构造结及邻区的下地壳黏滞系数。地形地貌解析方法将板块碰撞导致青藏高原整体隆升的变形简化为一种可以以量化形式表达的重力加载过程以模拟岩石圈变形的过程, 为青藏高原下地壳流概念的提出和相关定量参数的获取提供依据。首先, 以若尔盖-红原盆地为中心, 采集了解析半径约350km的9条呈扇形分布的地形条带(图 2); 然后, 通过下地壳管道流模型反演一系列空间均匀的下地壳黏度的地形剖面, 并与真实的条带状剖面地形梯度变化特征进行拟合比较(图 3); 最终, 选择与真实地形剖面最吻合的剖面的黏滞系数结果作为此区域的下地壳黏滞系数。

	Figure Option View Download New Window
	图 2 区域地貌和条带状剖面位置分布图橘黄色长条为本文所取的地形条带, 褐色实线为4km等高线, 红色实线为3km等高线, 黄色实线为2km等高线, 绿色实线为1km等高线Fig. 2 Regional topography and distribution of location of banded profiles.

	Figure Option View Download New Window
	图 3 模型结果与地形剖面黑色实线为真实地形剖面, 红色实线为黏滞系数反演获得的地形剖面Fig. 3 Model results and topographic profiles.

2.1 下地壳管道流模型

Clark等(2000)提出的下地壳管道流模型将下地壳看作一个厚度均匀的通道, 在这个通道中地壳物质可随着横向压力梯度变化而流动, 进而引起地形变化。

在二维模型中, Turcotte等(1982)假设牛顿流体通过厚度为h的通道时, Poiseuille流在通道顶部和底部的流速为0, 而通道中物质的流动速度(u)与黏滞系数(μ )、横向压力梯度 $(\frac{d p}{d x})$ 和在通道中的深度(z)存在以下函数关系:

$u = \frac{1}{2 μ} \frac{d p}{d x} (z^{2} - h z)$ （1）

通道中物质的流量(U)可通过速度在厚度上的积分获得:

$U = \int_{0}^{h} u (z) d z$ （2）

同时, 流量与地壳厚度(c)随时间(t)的变化有关:

$\frac{d c}{d t} = - \frac{d U}{d x} = \frac{1}{12} h^{3} \frac{d}{d x} (\frac{1}{μ} \frac{d p}{d x})$ （3）

模型假设通道中的横向压力梯度仅是地形的函数, 即p=ρ _cgT(x)。同时引入Airy模式的地壳均衡假说, 即将地形所增减的质量补偿于山根或反山根。 Airy模型表明, 大陆上山根的大小(M)与地形高程(T)线性相关, 即M= $\frac{ρ_{c}}{ρ_{m} - ρ_{c}}$ T。地壳厚度(c)与地形高程(T)的关系式为

$\frac{c}{T} = \frac{M + T}{T} = \frac{ρ_{m}}{ρ_{m} - ρ_{c}}$ （4）

随着下地壳中地壳物质的流动, 地形高程随时间的变化可表示为

$\frac{d T}{d t} = \frac{(ρ_{m} - ρ_{c})}{ρ_{m}} [\frac{1}{12} h^{3} ρ_{c} g \frac{d}{d x} (\frac{1}{μ} \frac{d T}{d x})]$ （5）

其中, T(x)为地形高程的函数, ρ _m为地幔密度(3 300kg/m³), ρ _c为地壳密度(2 600kg/m³), g为重力加速度, μ 为黏滞系数。根据地震学及大地电磁数据获得的中下地壳中低速、低阻的软弱层结果(Zhang et al., 2010; Yang et al., 2012; 朱介寿等, 2017), 设定通道厚度h为20km, 并假定黏滞系数在同一剖面并不随空间距离而变化。

前人的研究(Harrison et al., 1992; Clark et al., 2000)假定20Ma BP青藏高原在该区域发生隆升, 但本文将分为3类时间尺度对研究区内的9条剖面进行模拟。首先, 对于共和盆地、循化盆地及贵德盆地附近的青海南山和拉脊山等山系, 根据前人利用地磁地层学(Zhang et al., 2012)以及碎屑锆石U-Pb年代学研究(Lease et al., 2007)得到的6~10Ma BP开始隆升的结果, 假定剖面A— C穿过的区域在10Ma BP开始隆升。其次, 据Yuan等(2013)的研究结果可知, 约15Ma BP以来青藏高原东北缘NE-SW向甚至ENE-WSW向加速缩短变形, 模拟剖面D— F穿过的西秦岭等区域在15Ma BP开始隆升。最后, 关于龙门山区域存在的差异隆升, 侯明才等(2012)对磷灰石和锆石的裂变径迹年龄进行分析, 认为龙门山南段在38~10Ma BP发生快速隆升、北段在10~0Ma BP快速隆升; 此外, 唐哲民等(2011)对龙门山中、南段测定的结果表明其在20Ma BP左右开始快速隆升。因此, 针对剖面G— I的位置, 我们模拟其在10Ma BP开始隆升。

地形高程随时间的变化是下地壳流流动的结果。通过输入地形剖面数据可由以上模型公式反演获得下地壳的黏滞系数, 进而可推理下地壳流在地质学时间尺度上如何作用于现今构造地貌形态, 并最终揭示出构造运动的历史过程。

2.2 GPS数据与处理

由于下地壳黏滞系数仅能反映中— 新生代以来地壳深部的动力学特征, 为了在不同时空尺度上分析西秦岭-松潘构造结的演化过程, 引入GPS速度场观测现今地壳的形变过程, 并开展对比分析。

本文使用的GPS观测数据来源于中国大陆构造环境监测网络(CMONOC)二期工程以及国际GNSS服务提供的部分IGS观测数据。 GPS观测数据包括2009年以来西秦岭-松潘构造结附近所有的连续GPS数据与2009、 2011、 2013、 2015、 2017年的流动GPS观测数据。另外, 汶川地震前1999— 2007年的GPS速度场结果采用王敏(2009)解算的速度场结果; 2009— 2018年的GPS速度场结果则由作者自行解算得到。

GPS数据处理分为3个主要步骤: 首先, 使用GAMIT程序中的单日松弛解处理, 将区域观测数据与全球IGS站的数据合并解算, 得到待估坐标及其协方差矩阵; 然后, 将上步获得的单日松弛约束解与SOPAC(Scripps Orbital and Position Analysis Center)提供的ITRF2014全球框架解通过GLOBK软件进行合并, 获得在ITRF2014参考框架下的合并解; 最后, 利用GLOBK软件, 通过卡尔曼滤波程序估算站点的位置与速度。

经过以上处理的速度场数据以ITRF2014全球框架为参考框架, 不能直观地反映研究区西秦岭-松潘构造结及邻区的地壳形变。因此, 需将速度场的参考框架由ITRF2014全球框架转换为天水-成县块体区域参考框架, 尽可能地最小化块体内部的稳定运动, 以观察西秦岭-松潘构造结相对天水-成县块体的地壳运动趋势。

3 结果

3.1 西秦岭-松潘构造结及邻区的下地壳黏滞系数

西秦岭-松潘构造结南部为松潘-甘孜地块, Xie等(2013)通过地震学研究认为其下地壳处于部分熔融状态, 平均海拔为4~5km, 与周围山体的高差不大, 而下地壳黏滞系数的估计主要考虑研究区内最高、最低点的海拔高度及其之间的距离等构成曲线的参数。西秦岭-松潘构造结由于受到印度板块NE向的推挤作用而发生造山过程, 形成了阿尼玛卿山、太子山、光盖山-迭山和岷山等新生代造山带, 因此拟合曲线的起始点为地形梯度变化较大的区域, 多为新生代造山带的最高点。 Clark等(2000)与Wang等(1998)均认为最大地形包络线是先前抬升面在现今的高程位置, 因此本文选取新生代造山带的最大高程点与区域地形的最低点作为图 3 中各个剖面拟合红线的起点和终点, 以约束下地壳黏滞系数。

我们首先分析了若尔盖盆地北侧、西北侧跨越拉脊山、共和盆地、龙羊峡的3条剖面(A— C)的地貌形态, 确定了青藏高原东北缘的流变学边界特征, 或若尔盖盆地下地壳流变物质对其北侧地壳的影响范围; 其次, 分析了东北侧、东侧及东南侧6条地形剖面(D— I)的形态, 并与采用不同黏度系数的下地壳管道流模型计算得到的地形剖面结果进行对比, 得到的结果为(表1): 黏滞系数μ 沿6条剖面的顺时针方向(D— I)增大, 变化范围为9× 10¹⁸~1× 10²⁰Pa· s。该结果可理解为若尔盖盆地北侧及东北侧下地壳管道流物质具有低黏度的性质, 东南侧地区下地壳管道流物质可能具有高黏滞系数的特征。

表1 西秦岭-松潘构造结及邻区岩石圈黏滞系数估计 Table1 Approximate lithospheric viscosity estimation of the western Qinling-Songpan continental tectonic node and the adjacent regions

由于若尔盖盆地北侧、东北侧的下地壳黏滞系数小于其东侧及东南侧(图 3), 这在一定程度上说明若尔盖盆地向N或者NE向推挤变形, 即西秦岭-松潘构造结北部(即甘东南地区)的下地壳有向NE流动的趋势。

3.2 GPS速度场

对比1999— 2007年与2009— 2018年期间的GPS速度场结果(图4)可知, 相对于天水-成县块体的结果显示2008年汶川地震之前GPS在西秦岭-松潘构造结区域并没有观测到明显的地壳缩短现象, 揭示龙门山断裂处于完全闭锁状态; 汶川地震发生之后, GPS速度场在龙门山断裂和3km等高线区被明显划分为的2个区域, 2017年九寨沟M_S7.0地震和2013年岷县漳县M_S6.6地震就发生在闭锁3km等高线附近(图 2 中的红色等高线)。汶川地震破裂可能触发或加速了龙门山以北3km等高线区的应力积累和释放过程。

	Figure Option View Download New Window
	图 4 1999— 2007年(a)与2009— 2018年(b)期间相对于天水-成县块体的GPS速度场蓝色箭头为连续观测站结果, 红色箭头为流动观测站结果Fig. 4 GPS velocity field with respect to the Tianshui-Chengxian block between 1999— 2007(a) and 2009— 2018(b).

4 讨论

4.1 西秦岭-松潘构造结的区域构造特征分析

研究结果表明, 西秦岭-松潘构造结及邻区东南侧的下地壳黏滞系数最高, 向W、向N逐渐减小。式(1)说明黏滞系数与流动速度呈反比, 即黏滞系数越大则越不容易流动。因此, 下地壳流体无法向构造结东南侧流动, 而是向黏滞系数较小的NE向流动。研究结果表明青藏高原东北缘下地壳流向NE的弥散扩散运动也影响了西秦岭-松潘构造结及其邻区。下地壳流向NE的扩散导致在西秦岭形成一系列向NE凸出的断裂, 且具有明显的逆冲性质, 如临潭-宕昌断裂等, 并在东侧产生SN向或NE向的逆走滑断裂, 如岷江断裂和哈南-稻畦子断裂等; 更南侧发育具有右旋性质的NE向断裂, 如龙日坝断裂和龙门山断裂。此模型解释了西秦岭-松潘构造结发育不同走向、不同性质的活动断裂系和非常频繁、密集的大震活动的原因。

阿尼玛卿造山带的隆起导致东昆仑断裂的左旋走滑速率向E逐渐降低, 并转换发育了西秦岭-松潘构造结东缘的褶皱造山带, 内部存在若干条左旋走滑到逆冲的弧形转换断裂带。这些断裂带具有极低的滑动速率且广泛平行分布, 与造山带地形地貌有很好的匹配。同时, 西秦岭北缘断裂在通过阿尼玛卿山的弧形构造转换过程中吸收了一部分来自青藏高原中南部向N推挤变形的应变能量, 在断裂处于强闭锁的状态下, 可能会导致东昆仑与西秦岭北缘断裂带的次级走滑逆冲断裂带发生地震, 2013年甘肃岷县漳县M_S6.6地震正是在这样的构造背景下发生的位于走滑逆冲转换部位(葛伟鹏, 2013)的、靠近断层面脆性层底部的一次破裂事件。其发生在临潭-宕昌断裂和西秦岭北缘断裂之间的弧形逆冲变形带上, 从震源机制解来看(图 1), 主要以逆冲为主, 伴随有非常微弱的走滑分量, 可以认为此次地震反映了西秦岭北缘断裂带周边次级断裂的破裂过程。因此, 阿尼玛卿造山带的形成与演化过程能够影响整个西秦岭-松潘构造结的形成、发展和演化。

临潭-宕昌断裂、迭山-光盖山断裂、白龙江断裂及塔藏断裂等一系列弧形断裂构造与褶皱的形成, 可以解释为是在较长的地质学时间尺度(30~10Ma)内受到若尔盖盆地下地壳流沿着低黏度梯度和热梯度 N20° ~30° E向区域运动演化的结果。

然而, 以上结论仅限于以若尔盖盆地为中心的半径约200km的东侧及东北侧局部范围内。在西北一侧, 有研究表明10Ma BP以来存在1次快速隆升过程, 例如临夏盆地自7.8Ma BP起至1.8Ma BP持续堆积, 随后随着黄河、大夏河的出现, 开始河流下切侵蚀和堆积风成黄土的过程, 最终形成现有地貌(袁道阳等, 2007b); 贵德盆地约8.2Ma BP起快速持续隆升(宋春晖等, 2001); 共和盆地附近的青海南山和拉脊山等山系在6~10Ma BP开始隆升(Zhang et al., 2012)。本文假设根据年代学数据对盆地堆积时间的估计即为区域高原演化的平均时间, 而地表河流等侵蚀发生的时间和区域相对本研究而言时间和空间尺度较小, 对下地壳黏滞系数结果的影响可以忽略不计。而西北一侧由于受到东昆仑断裂及鄂拉山和拉脊山隆起等影响, 引发下地壳中可能存在的多个黏滞系数不同的流变介质流动, 进而导致EW向的挤压变形。因此, 上述断裂的形成与此次快速隆升事件的关系仍需开展深入研究。

4.2 青藏高原及其周缘中下地壳黏滞系数对青藏高原下地壳流演化的启示

前人通过大地测量学观测青藏高原内部及周缘地震的震后变形, 给出了相关区域的下地壳黏滞系数。例如, 王庆良等(1997)估计通海、炉霍、共和地震的震后指数松弛特征时间平均为5a, 假定地壳的剪切模量为4× 10¹⁰Pa, 则可得到地壳的黏度为6.3× 10¹⁸Pa· s; 沈正康等(2003)在研究东昆仑活动断裂近70a 5次7级以上地震间的黏滞应力触发时采用王庆良等(1997)的研究结果, 取中下地壳的黏滞系数为6.3× 10¹⁸Pa· s。我们通过松弛时间和黏滞系数的关系式τ _R=2η /μ 可发现, 6.3× 10¹⁸Pa· s对应了约10a的松弛时间。同时, 万永革等(2003)认为上地壳为孕震脆性层, 黏度不可能很低, 估计为2.0× 10¹⁹Pa· s; Ryder等(2007)在研究玛尼地震时给出的黏滞系数为4× 10¹⁸Pa· s; Ryder等(2010)等对西藏改则地震的震后余滑进行了研究, 取中— 下地壳的黏滞系数3× 10¹⁷Pa· s作为Maxwell半空间模型的输入参数; Ryder等(2011)使用Burger体流变学模型对2001年M_W7.8可可西里(昆仑山)地震的震后余滑和黏弹性松弛等进行研究, 得到下地壳震后初期的瞬态黏滞系数和经过若干年后的稳态黏滞系数分别为9× 10¹⁷Pa· s和1× 10¹⁹Pa· s, 并与玛尼地震的流变学参数进行对比, 得到流变学黏滞系数的有效约束为5× 10¹⁷Pa· s。王晓芳等(2012)通过大量模拟发现, 发生管道流动的下地壳物质黏滞系数在青藏高原东部区可能为(1~5)× 10¹⁸Pa· s到(1~4)× 10²⁰Pa· s; 杨辉等(2013)模拟了青藏高原通道流模型, 认为青藏高原上、中地壳之间存在一低速层, 深度为(20± 5)km, 与本文的反演结果基本一致; 孙玉军等(2013)认为青藏高原存在着厚度最大、强度和等效黏滞系数最低的下地壳, 并根据其厚度20~30km、强度约0.1MPa, 得到其等效黏滞系数只有10¹⁸~10²¹Pa· s。上述研究表明, 随着对青藏高原中下地壳流变学特性研究的不断深入, 不同方法得到的黏滞系数和对变形特征的认识及观点趋于一致。

约45Ma BP以来, 印度与欧亚大陆的碰撞导致了喜马拉雅山脉的迅速隆起以及地势高但地形起伏并不大的中央高原的发展(Le Fort, 1975; Molnar et al., 1975)。其中, 中央高原如此平坦可归因于低强度的岩石圈阻止了由地形梯度产生的侧向压力梯度。侧向压力梯度是由地壳内部的厚度或密度不均而引起的, 而在下地壳足够弱的情况下, 它将通过下地壳管道流动而变形(Bird, 1991; Royden, 1996; Bott, 1999; Beaumont et al., 2001)。压力驱动下的流动可使上、下地壳存在差异性增厚现象, 并且可能在超过100km的距离内进行地壳的长距离转移(Synder et al., 1986; Block et al., 1990; Schmeling et al., 1990; Kruse et al., 1991; Marquart, 1991; Royden et al., 1997; Clark et al., 2000, 2005; McQuarrie et al., 2000)。因此, 中央高原的形成可具体归因于低黏度层的发展。中下地壳低黏度层的存在也得到了高原区域下方高温流(Hu et al., 2000)、高反射体和高导电体(Nelson et al., 1996)等证据的支持。根据上述不同方法得到的青藏高原的黏滞系数结果, 认为侧向压力梯度驱动着具有约10¹⁸Ps· s数量级黏滞系数的中央高原下地壳流向不同方向扩展, 但下地壳流是否扩展到青藏东北缘一直饱受争议。由黏滞系数结果反映的下地壳流动过程表明, 中央高原的下地壳流已经流入西秦岭-松潘构造结, 并向NE流动。

4.3 结合GPS速度场和下地壳黏滞系数分析西秦岭-松潘构造结不同时空尺度上的演化过程

通过地貌解析法得到的黏滞系数属于长时间尺度的地球深部动力驱动结果, 而GPS速度场揭示的现象属于现今短时间尺度的上地壳运动过程。根据西秦岭-松潘构造结黏滞系数由北向南逐渐增大的趋势, 可以推测下地壳流从青藏高原扩散过程中经过西秦岭-松潘构造结时在东南侧被黏滞系数较大的四川盆地的阻隔, 进而开始快速的造山运动。下地壳流转而往黏滞系数较低的NE向运动时, 带动脆性的上地壳一起向坚硬的鄂尔多斯地块、阿拉善地块方向运动, 受到远程效应在区域内缓慢造山, 形成了现今3km等高线和2km等高线的阶梯弧形地势展布(图 5)。为了确定现今的地壳运动方向, 我们引入了GPS速度场结果, 发现GPS数据揭示的现今地壳运动方向与黏滞系数揭示的下地壳运动演化方向一致。综合1976年以来6级以上地震的震源机制解结果也可发现, 大地震均发生在3km等高线附近。

	Figure Option View Download New Window
	图 5 西秦岭松潘构造结岩石圈三维模型绿色条带为3km等高线区域, 黑色箭头为下地壳流流动方向; 地壳结构来自深震反射及远震接收函数等结果(高锐等, 2006; Zhang et al., 2010; Yang et al., 2012; 姚志祥等, 2014; 朱介寿等, 2017)Fig. 5 A 3D model of the lithosphere in western Qinling-Songpan continental node.

另外, 前人的研究或囊括了整个青藏高原(Clark et al., 2000), 或仅针对青藏高原东缘(王晓芳等, 2012), 本文的研究与前人在空间尺度上存在差异。本文对青藏高原东北缘, 特别是对西秦岭-松潘构造结在地形地貌上的等高线分析和地形差异分析揭示出研究区受控于下地壳流, 并被多种观测结果所证实, 如地震学、大地电磁和地球物理探测等。同时, 在地形地貌方面, 前人的研究并未过多指出高程等高线呈椭圆形, 而椭圆形的地貌形态进一步说明青藏高原的形成演化过程具有流变特性, 也符合Zhang等(2004)提出的连续形变的模式, 未来值得针对此地区进行进一步研究与讨论。同时, 在时间尺度上本文将研究区域按照地质年代学等给出的演化时间分为3类给定的不同的模拟时间, 并且引入GPS速度场观察现今地壳形变, 进行了古今对比。

5 结论

地壳流动发生在地壳深部数十km以下的下地壳处, 限于现今技术无法直接进行观测。目前, 了解下地壳流动力学如何作用于地貌形态和地壳变形是研究下地壳活动的重要途径。本文主要通过地貌形态估算的下地壳黏滞系数结果(Ma尺度)和GPS速度场显示的地壳形变结果(10a尺度), 深化了对西秦岭-松潘构造结地区岩石圈动力学演化的认识, 建立下地壳流与不同时间尺度岩石圈变形特征的相互联系。

(1)西秦岭-松潘构造结周缘下地壳黏滞系数自东南侧四川盆地区域的1× 10²⁰Pa· s, 逆时针向西秦岭等区域逐渐减小到9× 10¹⁸Pa· s, 下地壳具有向NE流动的趋势。

(2)现今GPS速度场揭示的上地壳形变结果与下地壳黏滞系数反演的下地壳流流动方向一致, 可以认为汶川地震后的GPS形变场揭示的西秦岭-松潘构造结及邻区的下地壳与上地壳耦合良好, 下地壳现今仍有NE向的流动趋势, 带动上地壳运动进而发生相关变形, 10a尺度的GPS速度场与青藏高原东缘及东北缘地区现今的造山过程匹配良好。

(3)研究结果可以较好地解释西秦岭-松潘构造结及其周边造山带的形成、不同走向和性质断裂带的发育、发震构造模型和地形梯度特征等。

致谢国家重大科学工程“ 中国大陆构造环境监测网络” 为本文提供了GPS观测资料; IGS数据中心提供了全球IGS站资料; Robert King提供了GAMIT/GLOBK软件; Wessel等(1998)提供了GMT软件。在此一并表示感谢!

参考文献

文献列表

[1]	陈洪凯, 李吉均. 1997. 白龙江流域第四纪以来地貌发育基本模式研究[J]. 重庆交通学院学报, 16(1): 15—20. CHEN Hong-kai, LI Ji-jun. 1997. General approach on geomorphologic evolution in Bailongjiang Basin since Quaternary[J]. Journal of Chongqing Jiaotong Institute, 16(1): 15—20(in Chinese). [本文引用:1]
[2]	冯希杰, 董星宏, 刘春, 等. 2005. 范家坝-临江断裂活动与1879年甘肃武都南8级地震的讨论[J]. 地震地质, 27(1): 155—163. FENG Xi-jie, DONG Xing-hong, LIU Chun, et al. 2005. Discussion on the activity of Fanjiaba-Linjiang Fault and the south Wudu, Gansu Province M8 earthquake of 1879[J]. Seismology and Geology, 27(1): 155—163(in Chinese). [本文引用:2]
[3]	高锐, 王海燕, 马永生, 等. 2006. 松潘地块若尔盖盆地与西秦岭造山带岩石圈尺度的构造关系: 深地震反射剖面探测成果[J]. 地球学报, 27(5): 411—418. GAO Rui, WANG Hai-yan, MA Yong-sheng, et al. 2006. Tectonic relationship between the Zoige Basin of the Songpan block and the west Qinling orogen at lithosphere scale: Results of deep seismic reflection profiling[J]. Acta Geoscientica Sinica, 27(5): 411—418(in Chinese). [本文引用:1]
[4]	葛伟鹏. 2013. 岷县漳县6. 6级地震发震构造与区域地形地貌特征关系讨论[J]. 地震工程学报, 35(4): 840—847. GE Wei-peng. 2013. Discussion on the relationship between regional land form and seismogenic structure of the Minxian-Zhangxian M_S6. 6 earthquake[J]. China Earthquake Engineering Journal, 35(4): 840—847(in Chinese). [本文引用:1]
[5]	顾功叙. 1983. 中国地震目录(公元前1831年—公元1969年)[M]. 科学出版社. GU Gong-xu. 1983. Catalogue of Chinese Earthquakes, 1831BC—1969AD [M]. Science Press, Beijing(in Chinese). [本文引用:2]
[6]	韩竹军, 向宏发, 冉勇康. 2001. 青藏高原东缘礼县-罗家堡断裂带晚更新世以来的活动性分析[J]. 地震地质, 23(1): 43—48. HAN Zhu-jun, XIANG Hong-fa, RAN Yong-kang. 2001. Activity analysis of Lixian-Luojiapu fault zone in the east boundary of Tibetan plateau since the Late-Pleistocene[J]. Seismology and Geology, 23(1): 43—48(in Chinese). [本文引用:1]
[7]	侯康明, 雷中生, 万夫岭, 等. 2005. 1879年武都南8级大地震及其同震破裂研究[J]. 中国地震, 21(3): 295—310. HOU Kang-ming, LEI Zhong-sheng, WAN Fu-ling, et al. 2005. Research on the 1879 southern Wudu M8. 0 earthquake and its coseismic ruptures[J]. Earthquake Research in China, 21(3): 295—310(in Chinese). [本文引用:2]
[8]	侯明才, 李智武, 陈洪德, 等. 2012. 中—新生代龙门山的差异隆升[J]. 吉林大学学报(地球科学版), 42(1): 104—111. HOU Ming-cai, LI Zhi-wu, CHEN Hong-de, et al. 2012. Differential uplift process of Longmen Mountain in Mesozoic-Cenozoic[J]. Journal of Jilin University(Earth Science Edition), 42(1): 104—111(in Chinese). [本文引用:1]
[9]	潘保田, 高红山, 李吉均. 2002. 关于夷平面的科学问题: 兼论青藏高原夷平面[J]. 地理科学, 22(5): 520—526. PAN Bao-tian, GAO Hong-shan, LI Ji-jun. 2002. On problems of planation surface: A discussion on the planation surface in Qinghai-Xizang Plateau[J]. Scientia Geographica Sinica, 22(5): 520—526(in Chinese). [本文引用:1]
[10]	潘佳铁, 李永华, 吴庆举, 等. 2017. 基于密集流动地震台阵的青藏高原东北缘及邻区Rayleigh波相速度层析成像[J]. 地球物理学报, 60(6): 2291—2303. PAN Jia-tie, LI Yong-hua, WU Qing-ju, et al. 2017. Phase velocity maps of Rayleigh wave based on a dense coverage and portable seismic array in NE Tibetan plateau and its adjacent regions[J]. Chinese Journal of Geophysics, 60(6): 2291—2303(in Chinese). [本文引用:1]
[11]	沈正康, 万永革, 甘卫军, 等. 2003. 东昆仑活动断裂带大地震之间的黏弹性应力触发研究[J]. 地球物理学报, 46(6): 786—795. SHEN Zheng-kang, WAN Yong-ge, GAN Wei-jun, et al. 2003. Viscoelastic triggering among large earthquakes along the east Kunlun fault system[J]. Chinese Journal of Geophysics, 46(6): 786—795(in Chinese). [本文引用:1]
[12]	宋春晖, 方小敏, 高军平, 等. 2001. 青藏高原东北部贵德盆地新生代沉积演化与构造隆升[J]. 沉积学报, 19(4): 493—500. SONG Chun-hui, FANG Xiao-min, GAO Jun-ping, et al. 2001. Tectonic uplift and sedimentary evolution of the Guide Basin in the northeast margin of Tibetan plateau in Cenozoic Era[J]. Acta Sedimentologica Sinica, 19(4): 493—500(in Chinese). [本文引用:1]
[13]	孙玉军, 董树文, 范桃园, 等. 2013. 中国大陆及邻区岩石圈三维流变结构[J]. 地球物理学报, 56(9): 2936—2946. SUN Yu-jun, DONG Shu-wen, FAN Tao-yuan, et al. 2013. 3D rheological structure of the continental lithosphere beneath China and adjacent regions[J]. Chinese Journal of Geophysics, 56(9): 2936—2946(in Chinese). [本文引用:1]
[14]	唐哲民, 郭宪璞, 乔秀夫. 2011. 龙门山中、南段中—新生代隆升史: 来自裂变径迹的证据[J]. 岩石学报, 27(11): 3471—3478. TANG Zhe-min, GUO Xian-pu, QIAO Xiu-fu. 2011. Uplifting history of Meso-Cenozoic era in the central-southern part of Longmenshan region: Evidence from the fission-track ages[J]. Acta Petrologica Sinica, 27(11): 3471—3478(in Chinese). [本文引用:1]
[15]	万永革, 沈正康, 甘卫军, 等. 2003. 东昆仑活动断裂带大地震之间的弹性应力触发研究[J]. 西北地震学报, 25(1): 4—10. WAN Yong-ge, SHEN Zheng-kang, GAN Wei-jun, et al. 2003. Study on the elastic stress triggering among the large earthquakes in eastern Kunlun active fault zone[J]. Northwestern Seismological Journal, 25(1): 4—10(in Chinese). [本文引用:1]
[16]	王庆良, 巩守文, 张希, 等. 1997. 由1990年共和7. 0级地震震后垂直形变求得的地球介质有效弛豫时间和黏滞系数[J]. 地震学报, 19(5): 480—486. WANG Qing-liang, GONG Shou-wen, ZHANG Xi, et al. 1997. Effective relaxation time and viscosity of the earth inferred from the postseismic vertical deformations of the 1990 M_S7. 0 Gonghe earthquake[J]. Acta Seismologica Sinica, 19(5): 480—486(in Chinese). [本文引用:3]
[17]	王晓芳, 何建坤. 2012. 下地壳管道流动与青藏高原东缘大尺度构造地貌关系[J]. 中国科学(D辑), 42(4): 505—512. WANG Xiao-fang, HE Jian-kun. 2012. Channel flow of the lower crust and its relation to large-scale tectonic geomorphology of the eastern Tibetan plateau[J]. Science in China(Ser D), 42(4): 505—512(in Chinese). [本文引用:2]
[18]	杨辉, 滕吉文, 皮娇龙. 2013. 青藏高原通道流模型动力环境的数值模拟[J]. 地球物理学报, 56(8): 2625—2635. YANG Hui, TENG Ji-wen, PI Jiao-long. 2013. Numerical simulation of the geodynamical condition about the channel flow model in Tibetan plateau[J]. Chinese Journal of Geophysics, 56(8): 2625—2635(in Chinese). [本文引用:1]
[19]	杨文采, 侯遵泽, 徐义贤, 等. 2017. 青藏高原下地壳热变形和管道流研究[J]. 地质论评, 63(5): 1141—1152. YANG Wen-cai, HOU Zun-ze, XU Yi-xian, et al. 2017. A study on thermal deformation and lower crust channel flows in Qinghai-Xizang(Tibet) plateau[J]. Geological Review, 63(5): 1141—1152(in Chinese). [本文引用:1]
[20]	杨晓平, 冯希杰, 黄雄南, 等. 2015. 礼县-罗家堡断裂晚第四纪活动特征: 兼论1654年礼县8级地震孕震机制[J]. 地球物理学报, 58(2): 504—519. YANG Xiao-ping, FENG Xi-jie, HUANG Xiong-nan, et al. 2015. The Late Quaternary activity characteristics of the Lixian-Luojiabu Fault: A discussion on the seismogenic mechanism of the Lixian M8 earthquake in 1654[J]. Chinese Journal of Geophysics, 58(2): 504—519(in Chinese). [本文引用:1]
[21]	姚志祥, 王椿镛, 曾融生, 等. 2014. 利用接收函数方法研究西秦岭构造带及其邻区地壳结构[J]. 地震学报, 36(1): 1—19. YAO Zhi-xiang, WANG Chun-yong, ZENG Rong-sheng, et al. 2014. Crustal structure in western Qinling tectonic belt and its adjacent regions deduced from receiver functions[J]. Acta Seismologica Sinica, 36(1): 1—19(in Chinese). [本文引用:1]
[22]	尹力, 罗纲, 孙云强. 2018. 青藏高原东缘中下地壳流与地壳变形[J]. 地球物理学报, 61(10): 3933—3950. YIN Li, LUO Gang, SUN Yun-qiang. 2018. Middle-lower crust flow and crustal deformation: Insights from a finite element modeling[J]. Chinese Journal of Geophysics, 61(10): 3933—3950(in Chinese). [本文引用:1]
[23]	袁道阳, 雷中生, 何文贵, 等. 2007a. 公元前186年甘肃武都地震考证与发震构造探讨[J]. 地震学报, 29(6): 654—663. YUAN Dao-yang, LEI Zhong-sheng, HE Wen-gui, et al. 2007a. Textual research of Wudu earthquake in 186BC in Gansu Province, China and discussion on its causative structure[J]. Acta Seismologica Sinica, 29(6): 654—663(in Chinese). [本文引用:2]
[24]	袁道阳, 张培震, 方小敏, 等. 2007b. 青藏高原东北缘临夏盆地晚新生代构造变形及过程[J]. 地学前缘, 14(1): 243—250. YUAN Dao-yang, ZHANG Pei-zhen, FANG Xiao-min, et al. 2007b. Late Cenozoic tectonic deformation of the Linxia Basin, northeastern margin of the Qinghai-Tibet Plateau[J]. Earth Science Frontiers, 14(1): 243—250(in Chinese). [本文引用:1]
[25]	袁道阳, 张培震, 刘百篪, 等. 2004. 青藏高原东北缘晚第四纪活动构造的几何图像与构造转换[J]. 地质学报, 78(2): 270—278. YUAN Dao-yang, ZHANG Pei-zhen, LIU Bai-chi, et al. 2004. Geometrical imagery and tectonic transformation of Late Quaternary active tectonics in northeastern margin of Qinghai-Xizang plateau[J]. Acta Geologica Sinica, 78(2): 270—278(in Chinese). [本文引用:1]
[26]	张波, 王爱国, 袁道阳, 等. 2018. 基于多源遥感解译和野外验证的断裂几何展布: 以西秦岭光盖山-迭山南麓断裂为例[J]. 地震地质, 40(5): 1018—1039. doi: DOI: 103969/j. issn. 0253-4967. 2018. 05. 005. ZHANG Bo, WANG Ai-guo, YUAN Dao-yang, et al. 2018. Fault geometry defined by multiple remote sensing images interpretation and field verification: A case study from southern Guanggaishan-Dieshan Fault, western Qinling[J]. Seismology and Geology, 40(5): 1018—1039(in Chinese). [本文引用:1]
[27]	张国伟, 郭安林, 姚安平. 2004. 中国大陆构造中的西秦岭-松潘大陆构造结[J]. 地学前缘, 11(3): 23—32. ZHANG Guo-wei, GUO An-lin, YAO An-ping. 2004. Western Qinling-Songpan continental tectonic node in China’s continental tectonics[J]. Earth Science Frontiers, 11(3): 23—32(in Chinese). [本文引用:1]
[28]	张培震, 邓起东, 张竹琪, 等. 2013. 中国大陆的活动断裂、地震灾害及其动力过程[J]. 中国科学(D辑), 43(10): 1607—1620. ZHANG Pei-zhen, DENG Qi-dong, ZHANG Zhu-qi, et al. 2013. Active faults, earthquake hazards and associated geodynamic processes in continental China[J]. Science in China(Ser D), 43(10): 1607—1620(in Chinese). [本文引用:1]
[29]	张培震, 闻学泽, 徐锡伟, 等. 2009. 2008年汶川8. 0级特大地震孕育和发生的多单元组合模式[J]. 科学通报, 54(7): 944—953. ZHANG Pei-zhen, WEN Xue-ze, XU Xi-wei, et al. 2009. Tectonic model of the great Wenchuan earthquake of May 12, 2008, Sichuan[J]. Chinese Science Bulletin, 54(7): 944—953(in Chinese). [本文引用:1]
[30]	郑文俊, 袁道阳, 张培震, 等. 2016. 青藏高原东北缘活动构造几何图像、运动转换与高原扩展[J]. 第四纪研究, 36(4): 775—788. ZHENG Wen-jun, YUAN Dao-yang, ZHANG Pei-zhen, et al. 2016. Tectonic geometry and kinematic dissipation of the active faults in the northeastern Tibetan plateau and their implications for understand ing northeastward growth of the plateau[J]. Quaternary Sciences, 36(4): 775—788(in Chinese). [本文引用:1]
[31]	朱介寿, 王绪本, 杨宜海, 等. 2017. 青藏高原东缘的地壳流及动力过程[J]. 地球物理学报, 60(6): 2038—2057. ZHU Jie-shou, WANG Xu-ben, YANG Yi-hai, et al. 2017. The crustal flow beneath the eastern margin of the Tibetan plateau and its process of dynamics[J]. Chinese Journal of Geophysics, 60(6): 2038—2057(in Chinese). [本文引用:1]
[32]	Avouac J P, Tapponnier P. 1993. Kinematic model of active deformation in Central Asia[J]. Geophysical Research Letters, 20(10): 895—898. [本文引用:1]
[33]	Bao X Y, Sand vol E, Ni J, et al. 2011. High resolution regional seismic attenuation tomography in eastern Tibetan plateau and adjacent regions[J]. Geophysical Research Letters, 38(16): L16304. [本文引用:1]
[34]	Beaumont C, Jamieson R A, Nguyen M H, et al. 2001. Himalayan tectonics explained by extrusion of a low-viscosity crustal channel coupled to focused surface denudation[J]. Nature, 414(6865): 738—742. [本文引用:1]
[35]	Bird P. 1991. Lateral extrusion of lower crust from under high topography in the isostatic limit[J]. Journal of Geophysical Research, 96(B6): 10275—10286. [本文引用:3]
[36]	Block L, Royden L H. 1990. Core complex geometries and regional scale flow in the lower crust[J]. Tectonics, 9(4): 557—567. [本文引用:2]
[37]	Bott M H. 1999. Modeling local crustal isostasy caused by ductile flow in the lower crust[J]. Journal of Geophysical Research, 104(B9): 20349—20359. [本文引用:1]
[38]	Brace W F, Kohlstedt D L. 1980. Limits on lithospheric stress imposed by laboratory experiments[J]. Journal of Geophysical Research, 85(B11): 6248—6252. [本文引用:1]
[39]	Chen S F, Wilson C, Deng Q D, et al. 1994. Active faulting and block movement associated with large earthquakes in the Min Shan and Longmen Mountains, northeastern Tibetan plateau[J]. Journal of Geophysical Research: Solid Earth, 99(B12): 24025—24038. [本文引用:1]
[40]	Clark M K, Bush J W, Royden L H. 2005. Dynamic topography produced by lower crustal flow against rheological strength heterogeneities bordering the Tibetan plateau[J]. Geophysical Journal International, 162(2): 575—590. [本文引用:1]
[41]	Clark M K, Royden L H. 2000. Topographic ooze: Building the eastern margin of Tibet by lower crustal flow[J]. Geology, 28(8): 703—706. [本文引用:8]
[42]	Diao F Q, Wang R J, Wang Y B, et al. 2018. Fault behavior and lower crustal rheology inferred from the first seven years of postseismic GPS data after the 2008 Wenchuan earthquake[J]. Earth and Planetary Science Letters, 495: 202—212. [本文引用:2]
[43]	England P C, McKenzie D. 1982. A thin viscous sheet model for continental deformation[J]. Geophysical Journal International, 70(2): 295—321. [本文引用:1]
[44]	England P, Houseman G. 1985. Role of lithospheric strength heterogeneities in the tectonics of Tibet and neighbouring regions[J]. Nature, 315(6017): 297—301. [本文引用:1]
[45]	England P, Houseman G. 1986. Finite strain calculations of continental deformation: 2. Comparison with the India-Asia collision zone[J]. Journal of Geophysical Research: Solid Earth, 91(B3): 3664—3676. [本文引用:1]
[46]	Goetze C, Evans B. 1979. Stress and temperature in the bending lithosphere as constrained by experimental rock mechanics[J]. Royal Astronomical Society Geophysical Journal, 59(3): 463—478. [本文引用:1]
[47]	Harrison T M, Copeland P, Kidd W S F, et al. 1992. Raising Tibet[J]. Science, 255(5052): 1663—1670. [本文引用:1]
[48]	Houseman G, England P. 1986. Finite strain calculations of continental deformation: 1. Method and general results for convergent zones[J]. Journal of Geophysical Research: Solid Earth, 91(B3): 3651—3663. [本文引用:1]
[49]	Hu S B, He L J, Wang J Y. 2000. Heat flow in the continental area of China: A new data set[J]. Earth and Planetary Science Letters, 179(2): 407—419. [本文引用:1]
[50]	Jin Y, McNutt M K, Zhu Y S. 1994. Evidence from gravity and topography data for folding of Tibet[J]. Nature, 371(6499): 669—674. [本文引用:1]
[51]	Kirby S H. 1983. Rheology of the lithosphere[J]. Reviews of Geophysics and Space Physics, 21(6): 1458—1487. [本文引用:1]
[52]	Kruse S, McNutt M K, Phipps-Morgan J, et al. 1991. Lithospheric extension near Lake Mead, Nevada: A model for ductile flow in the lower crust[J]. Journal of Geophysical Research, 96(B3): 4435—4456. [本文引用:2]
[53]	Le Fort P. 1975. Himalayas, the collided range: Present knowledge of the continental arc[J]. American Journal of Science, 275(1): 1—44. [本文引用:1]
[54]	Lease R O, Burbank D W, Gehrels G E, et al. 2007. Signatures of mountain building: Detrital zircon U/Pb ages from northeastern Tibet[J]. Geology, 35(3): 239. [本文引用:1]
[55]	Liu Z, Park J, Rye D M. 2015. Crustal anisotropy in northeastern Tibetan plateau inferred from receiver functions: Rock textures caused by metamorphic fluids and lower crust flow?[J]. Tectonophysics, 661: 66—80. [本文引用:1]
[56]	Makovsky Y, Klemperer S L, Ratschbacher L, et al. 1996. INDEPTH wide-angle reflection observation of P-wave-to-S-wave conversion from crustal bright spots in Tibet[J]. Science, 274(5293): 1690—1691. [本文引用:1]
[57]	Marquart G. 1991. Finite element modeling of lower crustal flow: A model for crustal thinning variations[J]. Journal of Geophysical Research: Solid Earth, 96(B12): 20331—20335. [本文引用:1]
[58]	McQuarrie N, Chase C. 2000. Raising the Colorado Plateau[J]. Geology, 28(1): 91—94. [本文引用:1]
[59]	Molnar P, Tapponnier P. 1975. Cenozoic tectonics of Asia: Effects of a continental collision: Features of recent continental tectonics in Asia can be interpreted as results of the India-Eurasia collision[J]. Science, 189(4201): 419—426. [本文引用:2]
[60]	Nelson K D, Zhao W J, Brown L D, et al. 1996. Partially molten middle crust beneath southern Tibet: Synthesis of Project INDEPTH initial results[J]. Science, 274: 1684—1688. [本文引用:2]
[61]	Ren J J, Xu X W, Yeats R S, et al. 2013. Millennial slip rates of the Tazang Fault, the eastern termination of Kunlun Fault: Implications for strain partitioning in eastern Tibet[J]. Tectonophysics, 68: 1180—1200. [本文引用:1]
[62]	Ren J J, Xu X W, Zhang S M, et al. 2018. Surface rupture of the 1933 M7. 5 Diexi earthquake in eastern Tibet: Implications for seismogenic tectonics[J]. Geophysical Journal International, 212: 1627—1644. [本文引用:1]
[63]	Royden L H. 1996. Coupling and decoupling of crust and mantle in convergent orogens: Implications for strain partitioning in the crust[J]. Journal of Geophysical Research: Solid Earth, 101(B8): 17679—17705. [本文引用:1]
[64]	Royden L H, Burchfiel B C, King R W, et al. 1997. Surface deformation and lower crustal flow in eastern Tibet[J]. Science, 276(5313): 788—790. [本文引用:2]
[65]	Ryder I, Bürgmann R, Pollitz F. 2011. Lower crustal relaxation beneath the Tibetan plateau and Qaidam Basin following the 2001 Kokoxili earthquake[J]. Geophysical Journal International, 187(2): 613—630. [本文引用:2]
[66]	Ryder I, Bürgmann R, Sun J. 2010. Tand em afterslip on connected fault planes following the 2008 Nima-Gaize(Tibet)earthquake[J]. Journal of Geophysical Research, 115: B03404. [本文引用:2]
[67]	Ryder I, Parsons B, Wright T J, et al. 2007. Post-seismic motion following the 1997 Manyi(Tibet) earthquake: InSAR observations and modelling[J]. Geophysical Journal International, 169(3): 1009—1027. [本文引用:2]
[68]	Schmeling H, Marquart G. 1990. A mechanism for crustal thinning without lateral extension[J]. Geophysical Research Letters, 17(13): 2417—2420. [本文引用:1]
[69]	Searle M P. 2015. Mountain building, tectonic evolution, rheology, and crustal flow in the Himalaya, Karakoram, and Tibet[A]. In: Treatise on Geophysics Amsterdam, Elsevier, 4: 469—511. [本文引用:1]
[70]	Synder D, Barazangi M. 1986. Deep crustal structure and flexure of the Arabian Plate beneath the Zagros collisional mountain belt as inferred from gravity observations[J]. Tectonics, 5(3): 361—373. [本文引用:1]
[71]	Tapponnier P, Molnar P. 1976. Slip-line field theory and large-scale continental tectonics[J]. Nature, 264(5584): 419—426. [本文引用:1]
[72]	Tapponnier P, Peltzer G, Le Dain A Y, et al. 1982. Propagating extrusion tectonics in Asia: New insights from simple experiments with plasticine[J]. Geology, 10(12): 611—616. [本文引用:1]
[73]	Tian Y T, Kohn B P, Qiu N S, et al. 2018. Eocene to Miocene out-of-sequence deformation in the eastern Tibetan plateau: Insights from shortening structures in the Sichuan Basin[J]. Journal of Geophysical Research: Solid Earth, 123(2): 1840—1855. [本文引用:1]
[74]	Wang E, Burchfiel B C, Royden L H, et al. 1998. Late Cenozoic Xianshuihe-Xiaojiang, Red River, and Dali fault systems of southwestern Sichuan and central Yunnan, China[J]. Geological Society of America Special Papers, 327: 1—108. [本文引用:1]
[75]	Wdowinski S, Axen G J. 1992. Isostatic rebound due to tectonic denudation: A viscous flow model of a layered lithosphere[J]. Tectonics, 11(2): 303—315. [本文引用:1]
[76]	Wessel P, Smith W H F. 1998. New, improved version of generic mapping tools released[J]. EOS, Transactions, American Geophysical Union, 79(47): 579. [本文引用:1]
[77]	Xie J, Ritzwoller M H, Shen W, et al. 2013. Crustal radial anisotropy across eastern Tibet and the western Yangtze Craton[J]. Journal of Geophysical Research: Solid Earth, 118(8): 4226—4252. [本文引用:1]
[78]	Yang Y J, Ritzwoller M H, Zheng Y, et al. 2012. A synoptic view of the distribution and connectivity of the mid-crustal low velocity zone beneath Tibet[J]. Journal of Geophysical Research: Solid Earth, 117(B4): B04303. [本文引用:1]
[79]	Yang Y J, Zheng Y, Chen J, et al. 2010. Rayleigh wave phase velocity maps of Tibet and the surrounding regions from ambient seismic noise tomography[J]. Geochemistry, Geophysics, Geosystems, 11: Q08010. [本文引用:1]
[80]	Yuan D Y, Ge W P, Chen Z W, et al. 2013. The growth of northeastern Tibet and its relevance to large-scale continental geodynamics: A review of recent studies[J]. Tectonics, 32(5): 1358—1370. [本文引用:1]
[81]	Zhang H P, Craddock W H, Lease R O, et al. 2012. Magnetostratigraphy of the Neogene Chaka Basin and its implications for mountain building processes in the northeastern Tibetan plateau[J]. Basin Research, 24(1): 31—50. [本文引用:2]
[82]	Zhang P Z, Shen Z, Wang M, et al. 2004. Continuous deformation of the Tibetan plateau from global positioning system data[J]. Geology, 32(9): 809. [本文引用:1]
[83]	Zhang P Z. 2013. A review on active tectonics and deep crustal processes of the western Sichuan region, eastern margin of the Tibetan plateau[J]. Tectonophysics, 584: 7—22. [本文引用:1]
[84]	Zhang Z J, Yuan X H, Yun C, et al. 2010. Seismic signature of the collision between the east Tibetan escape flow and the Sichuan Basin[J]. Earth and Planetary Science Letters, 292(3-4): 254—264. [本文引用:1]

1997

0.0

... 地貌被严重地侵蚀破坏, 例如仅美武高原保留较完整的一块主夷平面, 武都地区残留多级岩溶夷平面(陈洪凯等, 1997 ...

2005

0.0

冯希杰, 董星宏, 刘春, 等. 2005. 范家坝-临江断裂活动与1879年甘肃武都南8级地震的讨论[J]. 地震地质, 27(1): 155—163.

FENG

Xi-jie

, DONG

Xing-hong

, LIU

Chun

, et al. 2005. Discussion on the activity of Fanjiaba-Linjiang Fault and the south Wudu, Gansu Province M8 earthquake of 1879[J]. Seismology and Geology, 27(1): 155—163(in Chinese).

The earthquake occurred in Jiezhou,Gansu Province on July 1,1879 (May 12,Guangxu 5,Qing Dynasty) is one of the largest earthquake events in Chinese history. The effect of this event spread over more than ten provinces. According to historical data,the magnitude of this earthquake has been estimated to be 8 or 71/2,and the macroscopic epicenter has been located at Mianshanheba (104.7E,33.2N),south of Wudu,Gansu Province,with type II precision of estimation (≤25km error). As the earthquake occurred in the areas of high mountain ridges difficult to be approached,it has not been studied in detail so far. It is one of the 3 M =8 earthquakes in China that their relation to active faults had not been revealed so far. Recently,we have found that in satellite images a NNE-trending lineament can be clearly observed along the northern foot of the Shuikeng Mountains to the northeast of Wenxian County,Gansu Province. It extends eastward from Shifang Village to the northwest of Wenxian County,passing through Liangjiaba,Malian River,Fanjiaba,Miaobeihou,Guanjiagou,Jianzuishan Mountains,Shuikengya,northern slope of the Fangmashan Mountains,Songjia Mountains and Shenjiana'an,and then gradually becomes unclear after crossing through the Bailongjiang River and turning northward at 500m downstream from the Majiaba. The lineament has a total length of about 30km,among which about 21km can be identified to be surface fracture zone (from the bank of the Bailongjiang River to the top of the western hills of Guanjiagou). The lineament offsets left-laterally a series of ridges and gullies. In comparison with geologic data of this region,this lineament image coincides well with the NEE-trending Fanjiaba-Linjiang Fault. The interpretation of satellite images for the whole region and re-collation of historical records about this earthquake have confirmed that the Fanjiaba-Linjiang Fault bears a close relation to the southern Wudu earthquake,and is most probably the causative fault of this earthquake. This study,therefore,provides new insights into the following aspects,such as the occurrence and mode of motion of the causative fault,the length of surface ruptures,the amount and variation of horizontal displacement along the fault,the location of macroscopic epicenter,the probable magnitude of the event and the distribution of seismic hazards etc. All these results have led to the satisfactory solution of outstanding issue about the causative fault of the 1879 southern Wudu earthquake. They are also of great importance to seismic risk assessment in the border areas of Gansu,Qinghai and Sichuan Provinces as well as in southeast Gansu Province.

Earthquake Administration of Shaanxi Province, Xi'an 710068, China

1879年甘肃武都南8级地震发震断裂的确认是一个未决的问题。文中通过卫星影像解译、史料记载分析,认为沿文县东北水坑山北麓NEE向的范家坝-临江断裂可能分布有该次地震的地表破裂带,因而,这一条断裂可能是该次地震的发震断裂。由此,可在发震断裂的产状变化、活动方式、地表破裂带长度、水平位错量大小及沿断裂的分布、断裂的区域归属、宏观震中位置、可能震级大小、震害分布等诸多方面取得一致。

... 冯希杰等, 2005 ...

... 冯希杰等, 2005)、 2008年汶川M_S8 ...

2006

0.0

2013

0.0

葛伟鹏. 2013. 岷县漳县6. 6级地震发震构造与区域地形地貌特征关系讨论[J]. 地震工程学报, 35(4): 840—847.

Wei-peng

. 2013. Discussion on the relationship between regional land form and seismogenic structure of the Minxian-Zhangxian M_S6. 6 earthquake[J]. China Earthquake Engineering Journal, 35(4): 840—847(in Chinese).

To clearly recognize and understand the geomorphologic characteristics and seismogenic structure of the Minxian-Zhangxian MS6.6 earthquake,we use DEM （Digital Elevation Model） data to analyze the landform characteristics of southeastern Gausu.Regional tectonic environment and crustal kinematic characteristics at northeastern margin of Tibet Plateau are discussed combined with the distribution of regional active faults and their kinematic features around the hypocentral region of Minxian-Zhangxian MS6.6 earthquake.The seismogenic conditions including tectonic environment,activity of seismogenic fault and seismogenic process are also studied.In this paper,we use terrain profile method to analyze the geomorphologic characteristics of source region of this earthquake to reflect the relation between regional geomorphologic characteristic and seismogenic structure.Deformation characteristic of regional middle and upper crust and seismogenic process are explored from the geomorphologic point of view.At last,regional seismogenic structure and geodynamics background are discussed.We suggest that the Minxian-Zhangxian MS6.6 Earthquake is related with coseismic and postseismic deformation process of the Wenchuan MSS.0 earthquake.

为了清晰认识岷县漳县6.6级地震的发震构造环境和区域地貌特征,本文利用DEM（数字高程模型）数据分析了甘东南地区的地形地貌基本特征,结合区域活动断裂分布及其运动学特征讨论了岷县漳县6.6级地震所处在的青藏高原东北缘的区域构造环境和地壳运动学特征,研究了甘肃东南部的基本构造环境、发震断裂的断裂活动性及孕震过程等基本发震条件.主要利用地形剖面方法分析了通过地震震源区的地貌特征,反映出区域地形地貌特征与发震构造的关系,从地貌学角度探讨了区域中上地壳变形特征及孕震过程.最后讨论了区域发震构造、地球动力学背景,通过地形剖面及区域地貌分析了岷县漳县6.6级地震发震构造特点,认为此次地震可能与汶川地震的同震及震后变形过程相关.

... 6地震正是在这样的构造背景下发生的位于走滑逆冲转换部位(葛伟鹏, 2013)的、靠近断层面脆性层底部的一次破裂事件 ...

1983

0.0

... 130a的1879AD武都南8级大地震(顾功叙, 1983 ...

... 杨晓平等, 2015)、 1879年武都南8级地震(顾功叙, 1983 ...

2001

0.0

... 历史上发生过多次7级以上大地震, 如1654年天水南8级地震(韩竹军等, 2001 ...

2005

0.0

... 侯康明等, 2005)等 ...

... 侯康明等, 2005 ...

2012

0.0

侯明才, 李智武, 陈洪德, 等. 2012. 中—新生代龙门山的差异隆升[J]. 吉林大学学报(地球科学版), 42(1): 104—111.

HOU

Ming-cai

, LI

Zhi-wu

, CHEN

Hong-de

, et al. 2012. Differential uplift process of Longmen Mountain in Mesozoic-Cenozoic[J]. Journal of Jilin University(Earth Science Edition), 42(1): 104—111(in Chinese).

Based on analysis on fission track dating of apatite and zircon in the granite and sand samples collected from the south, middle and north segment of Longmen Mountain, it is found that the uplift process of Longmen Mountain can be divided into different segments along strike direction and zones in East-West direction. From Songpan-Ganzi fold belt through Longmen thrust belt to western Sichuan foreland basin, the entire Songpan-Ganzi fold belt has experienced regional uplift, and the fission track age shows positive correlation with altitude; while in Longmen thrust belt, the fission track age has negative or no correlation with altitude, suggesting that thrust fault play a dominant role during the uplift process. However, in western Sichuan foreland basin, the samples partly or entirely annealed with burial depth. On both sides of Maoxian-Wenchuan fault, there is an obvious difference in zircon fission track age but no evident difference for apatite, suggesting that the west of Maoxian-Wenchuan fault has undergone more rapid uplift during 38-10 Ma. On both the sides of Beichuan fault, apatite shows obvious fission track age, suggesting a quick uplift process occurred in the west of Beichuan fault during 10-0 Ma. Along strike direction, zircon fission track age increases gradually from north to south part of Longmen Mountain, which may indicate a more rapid uplift process in the northern part during Late Indosinian or Early Yanshanian. Apatite fission track age generally decreases from north through middle and to south, reflecting a more rapid uplift in the middle and south than in the north during Cenezoic.

1.State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu610059|China; 2.Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu610059|China

通过对采自龙门山南段、中段和北段花岗岩与砂岩样品中的磷灰石、锆石的裂变径迹年龄的分析，发现中生代以来龙门山的隆升在走向上存在分段性，在近东西方向上存在分带性。从松潘－甘孜褶皱带→龙门山冲断带→川西前陆盆地：松潘－甘孜褶皱带整体发生区域隆升，裂变径迹年龄与高程呈正相关关系；在龙门山冲断带，裂变径迹年龄与高程呈负相关关系或无关，说明冲断层在隆升过程中起主导作用；在川西前陆盆地，样品随埋深发生部分或全部退火。茂县－汶川断裂两侧锆石裂变径迹年龄差异明显而磷灰石裂变径迹年龄无明显差异，显示茂县－汶川断裂以西地区在38～10 Ma发生过更为快速的隆升；北川断裂两侧磷灰石裂变径迹年龄差异明显，表明北川断裂以西地区在10～0 Ma发生过快速隆升。从走向上看，从龙门山北段向南段，锆石裂变径迹年龄呈逐渐增大的趋势，这可能意味着印支末期或燕山早期，龙门山北段发生了更快的隆升；而磷灰石裂变径迹年龄总体上从龙门山北段向中段和南段呈递减趋势，反映新生代期间龙门山中、南段隆升更快。

... 最后, 关于龙门山区域存在的差异隆升, 侯明才等(2012)对磷灰石和锆石的裂变径迹年龄进行分析, 认为龙门山南段在38~10Ma BP发生快速隆升、北段在10~0Ma BP快速隆升 ...

2002

0.0

潘保田, 高红山, 李吉均. 2002. 关于夷平面的科学问题: 兼论青藏高原夷平面[J]. 地理科学, 22(5): 520—526.

PAN

Bao-tian

, GAO

Hong-shan

, LI

Ji-jun

. 2002. On problems of planation surface: A discussion on the planation surface in Qinghai-Xizang Plateau[J]. Scientia Geographica Sinica, 22(5): 520—526(in Chinese).

Planation surface is a remnant of landform in old age and the erosion surface is of a mature landform, according to the Davisian cycle. Studies on the long-term landscape evolution show that there are four types of planation surface, peneplain, pediplain, double leveling surfaces and cryoplain. The peneplain is formed through lowering of relief in wet region. The pediplain is developed by slope retreating in dry region. The double leveling surfaces appeares in Savanna landscape. The cryoplain is formed in periglacial environment. Measurement of erosion rates and retreating rates of slope indicated that formation of planation surface needs the tectonic equability for severl million years or thousands million years. In the the Qinghai-Xizang Plateau, there are two planation surfaces and one erosion surface, Summit Surface, Main Surface and Erosion Surface. The Summit Surface have formed in the Oligocene and early Miocene, and the Main Surface between 20-3.6Ma B.P. Tectonics on the Qinghai-Xizang Plateau were relatively stable between 3.6Ma B.P. and 1.7Ma B.P. and the Erosion Surfaces was formed. Because the Main Surface is a "jumping-off point" of the Qinghai-Xizang Plateau, studies on its mode of formation and height have great significance in determining the altitude of the Qinghai-Xizang Plateau before uplift. Synthesizing the proofs from mammal fauna, regolith and geomorphology, we think the Main Surface was developed as a typical double level surface. There could be the peneplain in the south of it and the pediplain on north. Its altitude should not exceed 1000 m when it was formed. The Intense tectonic uplift, which resulted in the present Qinghai-Xizang Plateau with an altitude of 4500-5000m, happened in last 3.6Ma when the Main Surface was destroyed.

MOE National Laboratory of Western China’s Environment & Department of Geography, Lanzhou University, Lanzhou, Gansu 730000

长期地貌演化研究表明,夷平面的形成有4种基本方式:准平原、山麓剥蚀平原、双层水平面和冻融剥夷平原。它们的形成都需要上千万年至数亿年的构造相对稳定时期。青藏高原上的层状地貌面可以划分为两级夷平面和一级剥蚀面。山顶面形成于渐新世至中新世早期;主夷平面是以双层水平面或山麓剥蚀平原形式发育的,大致形成于20～3.6 Ma B.P.期间,完成时的高度低于1000m;剥蚀面形成于3.6～1.7 Ma B.P.期间。

... 潘保田等, 2002) ...

2017

0.0

... , 2011)进行分析, 结果均证明青藏高原东北部存在中下地壳流(潘佳铁等, 2017) ...

2003

0.0

沈正康, 万永革, 甘卫军, 等. 2003. 东昆仑活动断裂带大地震之间的黏弹性应力触发研究[J]. 地球物理学报, 46(6): 786—795.

SHEN

Zheng-kang

, WAN

Yong-ge

, GAN

Wei-jun

, et al. 2003. Viscoelastic triggering among large earthquakes along the east Kunlun fault system[J]. Chinese Journal of Geophysics, 46(6): 786—795(in Chinese).

We study the stress transfer and triggering of large earthquakes along the East Kunlun fault system, northern Tibet. Five M≥7 earthquakes occurred along the fault zone during the past 70 years are considered: the M7.5 Huashi Canyon earthquake, the 1963 MS 7.1 Dulan earthquake, the 1973 MS7.3 Manyi earthquake, the 1997 MS7.5 Manyi earthquake, and the 2001 MW7.8 Kokoxili earthquake. We simulate the stress evolution process produced by seismic dislocations in layered viscoelastic media, and calculate the Coulomb failure stress change on the fault plane of each subsequent earthquake. The result shows that the Coulomb failure stress on the fault plane of the Kokoxili earthquake was increased by the previous 4 earthquakes, and theviscoelastic relaxation gradually enhanced the Coulomb failure stress field as time elapsed. By evaluating the Coulomb failure stress changes produced by the coseismic rupture and viscoelastic relaxation of the 4 preceding large earthquakes, we find that the Coulomb failure stress changes produced by the viscoelastic relaxation are much more significant than that produced by the coseismic deformation in 3 of the 4 earthquakes. The stress field simulation indicates that after the Kokoxili earthquake the Coulomb failure stress in the XidatanDongdatan segment (between the Kokoxili and Dulan segments) of the East Kunlun fault is increased as much as 0.05～0.10 MPa, implying increased probability of seismic hazard in this region.

1 Institute of Geology, China Seismological Bureau, Beijing, 100029, China 2 Dept of Earth and Space Sciences，University of California, Los Angeles, CA 900951567, USA 3 College of Disaster Prevention Technique, Yanjiao, Beijing, 101601, China 4 Seismological Lab, University of Nevada, Reno, NV 89577, USA

对青藏高原北部东昆仑破裂带大地震之间的应力转移和断层相互作用进行研究. 考虑1937年以来沿此破裂带发生的5个M≥7的地震：1937年M7.5花石峡地震，1963年MS7.1都兰地震，1973年MS7.3玛尼地震，1997年MW7.5玛尼地震和2001年MW7.8可可西里地震，模拟了黏弹性成层介质中地震断层错动产生的应力演化过程，并计算了在后续地震破裂面上产生的库仑破裂应力变化. 结果表明，前面4个地震均造成2001年可可西里地震断层面上库仑破裂应力的增加，并且中地壳和下地壳的黏弹性松弛效应使得库仑破裂应力场随着时间的推移而逐渐加强. 在计算过程中定量估计了可可西里地震发生时前面4个地震同震形变和黏弹性松弛导致可可西里地震破裂面上库仑破裂应力变化之间的比值，发现前3个地震由黏弹性松弛造成的变化远远大于同震形变所造成的变化. 可可西里地震之后应力场的模拟表明东昆仑断层中段的东大滩－西大滩断层段（位于可可西里地震破裂以东及都兰地震以西）的库仑破裂应力显著增加，变化值达0.05～0.1 MPa，预示这一地区地震危险性的增加.

... 沈正康等(2003)在研究东昆仑活动断裂近70a 5次7级以上地震间的黏滞应力触发时采用王庆良等(1997)的研究结果, 取中下地壳的黏滞系数为6 ...

2001

0.0

宋春晖, 方小敏, 高军平, 等. 2001. 青藏高原东北部贵德盆地新生代沉积演化与构造隆升[J]. 沉积学报, 19(4): 493—500.

SONG

Chun-hui

, FANG

Xiao-min

, GAO

Jun-ping

, et al. 2001. Tectonic uplift and sedimentary evolution of the Guide Basin in the northeast margin of Tibetan plateau in Cenozoic Era[J]. Acta Sedimentologica Sinica, 19(4): 493—500(in Chinese).

There are Iots of different viewpoints about the upIift of the Tibetan PIateau in the worId. The paper provides the proofs for recovering the history of the pIateau upIift by studying Cenozoic stratigraphy of Guide Basin in the northeast Tibetan PIateau. Cenozoic stratigraphy was deposited in Guide Basin wideIy and seven sedimentary facies associations are recognized . They are interpreted as the deposits of deep graveIIy braided, deIta, debris-fIow-dominated braided, shaIIow and haIf-deep Iake, fan deIta, graveIIy braided and piedmont proIuviaI systems, respectiveIy. The reIationship between the sedimentation of Guide basin and the upIift of the Tibetan PIateau reveaIs that the PIateau has experienced six phases in Cenozoic era：preIiminary upIift phase（Late OIigocene）, reIativeIy stabIe and denudation pIanation phase（EarIy-Miocene）, IittIe- scaIe upIift phase（Late EarIy-Miocene）, stabIe and denudation pIanation phase（MiddIe MiddIe-Miocene to Late MiddIe- Miocene）, sustain and stepwise upIift phase（8.2 ~ 3.6 Ma）, rapid and intense upIift phase（3.6 ~ 0 Ma）. The upIift in 3.6 Ma is an important stage of Cenozoic tectonic movements, before then the absoiute eievation of Guide Basin was beiow 1 000 m and since then tectonic movement became more active to form more compiex topography. So the upiift of Tibetan Piateau is a process of muitipie phases, uneguai speed, and irreguiar movement.

National Laboratory of Western China's Environmental Systems, College of Resource and Environment, Lanzhou University, Lanzhou 730000

通过对高原东北部贵德盆地新生代地层研究,为恢复高原隆升历史提供依据。贵德盆地形成于渐新世末,其新生代地层可划分出深水砾砂质网状河流、泥石流质网状河流、砾质网状河流、山麓洪积、三角洲、半深湖与浅湖、水下扇三角洲七个沉积相组合体系。根据其沉积相组合和沉积演化揭示出高原隆升过程先后经历了:早期隆升期 (渐新世末 )、较稳定剥蚀夷平期 (早中新世 )、小幅隆升期 (早中新世末 )、稳定剥蚀夷平期 (中中新世至晚中新世 )、持续逐步较快速隆升期 (8.2～ 3.6Ma)、急剧强烈阶段性隆升期 (3.6～ 0Ma) ;其中 3.6Ma±的隆升是新生代构造运动的一个重要分水岭,此前盆地海拔应不超过 10 0 0m,此后构造活动速度明显加速,地形高差显著增大。可见青藏高原的隆升是一个多阶段、不等速和非均变的复杂过程

... 2Ma BP起快速持续隆升(宋春晖等, 2001) ...

2013

0.0

孙玉军, 董树文, 范桃园, 等. 2013. 中国大陆及邻区岩石圈三维流变结构[J]. 地球物理学报, 56(9): 2936—2946.

SUN

Yu-jun

, DONG

Shu-wen

, FAN

Tao-yuan

, et al. 2013. 3D rheological structure of the continental lithosphere beneath China and adjacent regions[J]. Chinese Journal of Geophysics, 56(9): 2936—2946(in Chinese).

The rheological structure controls the intensity and styles of lithospheric deformation. With the constraint of the upper mantle temperature derived from seismic velocity and the surface temperature from the observation of meteorological stations, we have calculated the three-dimensional thermal structure of the continental lithosphere beneath China and adjacent regions according to the observed thermal parameters. Based on the 3D thermal structure and strain rates derived from GPS observation, we have calculated the rheological structure of the continental lithosphere with the constraint of the frictional slip, brittle fracture and creep. The results show that a weak ductile lower crust is widespread beneath China and adjacent regions. The weakest and thickest lower crust is found in the Tibetan plateau. The rheological strength and the effective viscosity of the lower crust are usually two orders of magnitude lower than that of the upper crust and the lithospheric mantle. The lithospheric strength and effective viscosity of the Tibetan plateau is lower than that of North China, South China and the Indian plate. In general, the lateral variations of the lithospheric rheology are consistent with the spatial patterns of late Cenozoic crustal deformation and gravity lineament.

Sun Yu-Jun 1 ;Fan Tao-Yuan 1 ;Dong Shu-Wen 2 ;Zhang Huai 3 ;Shi Yao-Lin 3 ;

依据地震波速得到的上地幔温度和气象台站记录的地表温度为约束,结合地表热流和热导率观测数据,利用有限元方法计算了中国大陆及邻区岩石圈三维热结构.基于此温度结果和GPS观测得到的应变率数据,以滑动摩擦、脆性破裂和蠕变三种强度机制为约束,计算得到了中国大陆及邻区岩石圈三维流变结构.结果显示:弱强度和低等效黏滞性系数的下地壳在中国大陆及邻区普遍存在,并且下地壳的流变强度和等效黏滞性系数比上地壳和岩石圈地幔一般要低1~2个数量级;中国大陆范围内青藏高原存在着厚度最大、强度最低的下地壳;青藏高原的岩石圈强度和等效黏滞性系数比华北、华南和印度板块的都要低;岩石圈流变结构的横向分布特征与重力梯度带和地形过渡带比较一致.

... 孙玉军等(2013)认为青藏高原存在着厚度最大、强度和等效黏滞系数最低的下地壳, 并根据其厚度20~30km、强度约0 ...

2011

0.0

唐哲民, 郭宪璞, 乔秀夫. 2011. 龙门山中、南段中—新生代隆升史: 来自裂变径迹的证据[J]. 岩石学报, 27(11): 3471—3478.

TANG

Zhe-min

, GUO

Xian-pu

, QIAO

Xiu-fu

. 2011. Uplifting history of Meso-Cenozoic era in the central-southern part of Longmenshan region: Evidence from the fission-track ages[J]. Acta Petrologica Sinica, 27(11): 3471—3478(in Chinese).

Through fission track chronology method, we have analyzed apatite and zircon of the Mesozoic sequence in the central-southern Longmenshan and simulated the thermal history and got the following results: (1) the Mesozoic sequence at the TianquaniHuaiyuan area in the central-southern Longmenshan had the strongest uplift in the Late Himalayan stage, coincident with the strong structure movement in the region. (2) For the profiles at southwestern and western Huaiyuan Town, the rapid uplift in Late Himalayan initiated front 20Ma in the west to 7 similar to 5Ma in the east and continued up to now, i. e., the beginning time of the uplift became younger from west to east, which is well corresponding with the eastwards progressive thrusting of the Longmenshan orogeny. (3) Some of local uplift events occurred at 165 similar to 155Ma, 140 similar to 77Ma and 55 similar to 22Ma.

[Tang ZheMin; Guo XianPu; Qiao XiuFu] Chinese Acad Geol Sci, Inst Geol, State Key Lab Continental Tecton & Dynam, Beijing 100037, Peoples R China.

运用裂变径迹年代学方法对龙门山中、南段中生代地层内的磷灰石、锆石进行分析,并进行了热历史模拟,结果表明:①龙门山中、南段天全、怀远一带中生代地层最主要的强烈隆升阶段为喜山晚期,与该区的强烈构造运动时期相一致;②怀远镇西南侧及西侧剖面,喜山晚期强烈隆升阶段的时间自西侧的20Ma左右开始至东侧的7~5Ma开始并延续至今,开始强烈隆升的时间自西向东逐步变新;与龙门山造山带逆冲推覆作用在时空上具向东前展式渐进推覆的特点相对应;③部分地区存在163~155Ma、140~77Ma、55~22Ma的隆升事件。

... 此外, 唐哲民等(2011)对龙门山中、南段测定的结果表明其在20Ma BP左右开始快速隆升 ...

2003

0.0

... 同时, 万永革等(2003)认为上地壳为孕震脆性层, 黏度不可能很低, 估计为2 ...

1997

0.0

... 黏滞系数是反映地球介质流变特性的重要参数之一(王庆良等, 1997), 前人已对青藏高原岩石圈下地壳的黏滞系数进行了反演与估计, 并开展了系统性的研究与分析 ...

... 例如, 王庆良等(1997)估计通海、炉霍、共和地震的震后指数松弛特征时间平均为5a, 假定地壳的剪切模量为4#cod#x000D7 ...

... 沈正康等(2003)在研究东昆仑活动断裂近70a 5次7级以上地震间的黏滞应力触发时采用王庆良等(1997)的研究结果, 取中下地壳的黏滞系数为6 ...

2012

0.0

... 王晓芳等(2012)通过大量模拟发现, 发生管道流动的下地壳物质黏滞系数在青藏高原东部区可能为(1~5)#cod#x000D7 ...

... , 2000), 或仅针对青藏高原东缘(王晓芳等, 2012), 本文的研究与前人在空间尺度上存在差异 ...

2013

0.0

杨辉, 滕吉文, 皮娇龙. 2013. 青藏高原通道流模型动力环境的数值模拟[J]. 地球物理学报, 56(8): 2625—2635.

YANG

Hui

, TENG

Ji-wen

, PI

Jiao-long

. 2013. Numerical simulation of the geodynamical condition about the channel flow model in Tibetan plateau[J]. Chinese Journal of Geophysics, 56(8): 2625—2635(in Chinese).

Being a possible geodynamical mechanism, "crustal flow" comes up with corresponding models in resolving and predicting the tectonics, metamorphism and exhumation of high terranes in the Himalayan-Tibetan orogenic system. This paper adopts 2-D viscoelastic models to discuss the geodynamical boundary condition for the deep material flow in Tibetan plateau, based on the average geophysical model of the crust and upper mantle. The result shows: (1) As non-smoothly contact mode, the solid materials of the lower crust and upper-mantle lid beneath the Tibetan plateau do not have the boundary condition to move mutually, which means that "channel flow" model cannot independently occur freely nearby Moho interface. The simultaneous transfer of the deep medium of "lower crust and upper-mantle lid" can possibly happen by the enough force source, which takes the low-velocity layers as upper detachment interface at depths 20 similar to 30 km, and the top of asthenosphere as lower detachment interface at depths 100 similar to 110 km. (2) "Channel flow" is hard to move without the former sufficient and necessary conditions. So, the deep materials flow in Tibetan plateau is not universal, and only happens in local and particular circumstance.

Yang Hui 1 ;Teng Ji-Wen 1 ;Pi Jiao-Long 1 ;

"中、下地壳流"模型作为一种可能的动力学演化机制,在解决诸如喜马拉雅造山带和青藏高原东缘、南缘等区域地壳中岩层的通道流或韧性剪切挤出等方面的解释给出了相应的模型和阐述.本文基于青藏高原壳、幔介质平均速度模型,采用二维黏弹性数值模型对高原下地壳物质流动的动力学边界条件进行探讨.研究结果表明:(1)青藏高原下地壳与上地幔盖层物质作为坚硬的固态物质相接,不具备可运动的边界条件,难以在Moho界面处任意地域发生相互运动.壳、幔介质中需存在可供物质高速运动的边界条件,即以上地壳底部的低速层为上滑移面,以上地幔软流圈顶部为下滑移面,才有可能在足够强的力系作用下促使"下地壳+岩石圈盖层"物质发生同步运移;(2)若不具备这样的初始与边界条件是难以产生深部物质运移的.因此,青藏高原深部壳、幔物质运动不可能是普遍存在的,只能是局部和在特异环境下才能实现.

... 杨辉等(2013)模拟了青藏高原通道流模型, 认为青藏高原上、中地壳之间存在一低速层, 深度为(20#cod#x000b1 ...

2017

0.0

... 另外, 利用地球物理学方法, 例如建立二维黏弹塑性有限元模型(尹力等, 2018)以及地壳三维密度图像分析(杨文采等, 2017)等, 其结果也支持青藏高原下地壳物质流动已到达青藏高原东北缘的假说 ...

2015

0.0

杨晓平, 冯希杰, 黄雄南, 等. 2015. 礼县-罗家堡断裂晚第四纪活动特征: 兼论1654年礼县8级地震孕震机制[J]. 地球物理学报, 58(2): 504—519.

YANG

Xiao-ping

, FENG

Xi-jie

, HUANG

Xiong-nan

, et al. 2015. The Late Quaternary activity characteristics of the Lixian-Luojiabu Fault: A discussion on the seismogenic mechanism of the Lixian M8 earthquake in 1654[J]. Chinese Journal of Geophysics, 58(2): 504—519(in Chinese).

We have studied the earthquake occurred in vicinity of Luojiabu, southwest of Tianshui city, Gansu Province, where the M =8 Lixian earthquake occurred on July 21, 1654. In geotectonic setting, this earthquake happened in the middle-northern segment of South-North Seismic Belt, which generates numerous strong earthquakes and consequently makes this area one of the most seismically hazardous regions in China. However, causative structure and mechanism of Lixian earthquake is still in debate. Combined with active fault mapping, deep geophysical data, globe position system vector field and the distribution of landslides along the fault, we discuss that the mechanism of Lixian earthquake and try to estimate the seismically hazardous in this region. Fault descriptions are based on field observations aided by satellite image from Google earth collected along the fault zone. Our primary purpose is to document features bearing on the recency and kinematics of Quaternary movement along the fault. The observations are largely synthesized on a set of maps. The maps show active fault traces and are annotated to indicate the location of features indicative of the sense, style and amount of offset of geomorphic features. We also map the distribution of Quaternary deposits in the vicinity of fault. Combined with the electrical structure profile derived by 2D inversion of the MT data, we analyzed seismogenic structures of Lixian 1654 earthquake.#br#On July 21, 1654, the Lixian M =8 earthquake occurred at the east part of Lixian County, Gansu Province, China, in the middle-northern segment of the South-North Seismic Belt. In this region the tectonic activities and deformation are closely related to the north-eastward growth of Tibetan Plateau. Their complicated structural geometries were controlled by the Eastern Kunlun fault, Northern Marginal fault of West-Qinling, and a series of north-east trending faults. The Lixian-Luojiabu fault is a northeast trending sinistral strike-slip active fault and is 150 km long consisted by three sub-segments aligned in right-step-echelon. The fault cuts the T 1 terrace (lowest terrace in this area) deposits which contain the red ceramic fragments marking the Yangshao layer. On the terrace surface, the height of fault scarp is about 1.5 m. Along the Lixian-Luojiabu fault, the sinistral displacement of gullies about 3~10 m and the height of fault scarps about 4.5~8 m are found in a number of locations. And the Knickpoints about 3.5~3.9 m high are found 16 m away from the fault scarps. According to knickpoint recession rates at the same environment, these knickpoints may be formed as a 1654 earthquake in Lixian. A large number of landslides are distributed in a belt along Lixian-Yanguan-Luojiabu-Tianshui towns line, and its major axis direction is consistent with the trending of the Lixian-Luojiabu fault. Rear walls and side walls of the landslides are steep, with the outcrops of Late Quaternary loess and little vegetation cover. The Lixian-Luojiabu active fault is the seismogenic fault of the Lixian M =8 earthquake in 1654. The south-eastward sliding of the Lixian Sub-block, which is surrounded by the Northern Marginal fault of West-Qinling, Lixian-Luojiabu fault, and the Minxian-Dangchang fault, led to the occurring of the Lixian M =8 earthquake in 1654. Differences in electrical structure for the crust on the two sides of Lixian—Luojiabu fault reveals the structural condition for strong earthquake generation. Lixian-Luojiabu fault is a sinistral strike-slip active fault, which generated M =8 Lixian earthquake on July 21, 1654. This earthquake produced 7~10 m horizontal offset and with 3~4 m fault scarps along the Lixian-Luojiabu fault. Tectonically, it took place on the middle-northern segment of the South-North Seismic Belt where a series of M >5 had already occurred. Based on analysis of activity of other faults, GPS vector field and deep structural condition, the Lixian-Luojiabu fault activities and deformation are closely related to the north-eastward growth of Tibetan Plateau.

1. Key Laboratory of Active Tectonics and Volcano, Institute of Geology, China Earthquake Administration, Beijing 100029, China; 2. Shanxi Earthquake Administration, Xi'an 710068, China

1654年7月21日甘肃省礼县8级地震发生在南北地震带的中北段, 该地区的构造变形和构造活动与青藏高原向北东方向的扩展密切相关, 复杂的构造几何特征主要受控于东昆仑断裂、西秦岭北缘断裂和一系列北东向断裂. 礼县—罗家堡断裂为一条北东东向的左旋走滑活动断裂, 错断了含有仰韶文化红色陶瓷片的一级阶地堆积物, 阶地面上断层陡坎高约1.5 m. 沿断裂带发现冲沟的左旋位错量为3~10 m, 晚更新世黄土中残留的断层陡坎高4.5~8 m. 其中两条冲沟中发现裂点, 高3.5~3.9 m, 距断层陡坎的距离为16 m. 礼县—盐关—罗家堡—天水镇一带发育大量的滑坡, 长轴走向与礼县—罗家堡断裂一致, 滑坡体后缘、侧壁陡峭, 出露晚第四纪黄土, 鲜有植被覆盖. 礼县—罗家堡断裂为1654年8级地震的发震断裂.综合分析认为, 受青藏高原向北东方向的扩展, 被西秦岭北缘断裂、礼县—罗家堡断裂和岷县—宕昌断裂围限的礼县次级地块向南东滑动可能导致了1654年礼县8级地震的发生. 断裂北、南两侧地壳电性结构的差异为强震的孕育提供了深部构造条件.

... 杨晓平等, 2015)、 1879年武都南8级地震(顾功叙, 1983 ...

2014

0.0

2018

0.0

2007

0.0

... 而历史文献记载西秦岭-松潘构造结北部, 即西秦岭北缘断裂以南的甘东南毗邻地区发生过多次破坏性地震, 包括离逝时间约2 200a的186BC甘肃武都7~7 1/4级地震(袁道阳等, 2007a)、离逝时间#cod#x0003E ...

... Zhang, 2013)、 186BC武都7~71/4级地震(袁道阳等, 2007a)、 1976年松潘7 ...

2007

0.0

... 8Ma BP持续堆积, 随后随着黄河、大夏河的出现, 开始河流下切侵蚀和堆积风成黄土的过程, 最终形成现有地貌(袁道阳等, 2007b) ...

2004

0.0

袁道阳, 张培震, 刘百篪, 等. 2004. 青藏高原东北缘晚第四纪活动构造的几何图像与构造转换[J]. 地质学报, 78(2): 270—278.

YUAN

Dao-yang

, ZHANG

Pei-zhen

, LIU

Bai-chi

, et al. 2004. Geometrical imagery and tectonic transformation of Late Quaternary active tectonics in northeastern margin of Qinghai-Xizang plateau[J]. Acta Geologica Sinica, 78(2): 270—278(in Chinese).

青藏高原东北缘所在的柴达木-祁连活动地块内的晚第四纪活动构造可以划分为主边界左旋剪切构造带、块内次级右旋剪切构造带和挤压会聚构造带等三种基本类型。在区域北东向构造应力作用下,块体发生了NE向的挤压缩短、顺时针方向的旋转和向SEE方向的挤出等构造变形。在块体内部形成了挤压推覆构造、次级剪切构造、剪切压扁构造和弧形挤出构造等四种典型的构造转换方式,实现不同方向与不同性质活动构造之间的转换平衡。

... 字弧形构造(袁道阳等, 2004 ...

2018

0.0

... 张波等, 2018) ...

2004

0.0

... 西秦岭-松潘构造结(图 1)位于青藏高原、华南地块、鄂尔多斯地块三大构造单元的交会地带, 又处于青藏高原东北缘扩展的前缘部位, 属于地壳尺度上的巨型构造结, 总体呈倒三角形, 具有独特的从地表到深部的地质与动力学特征(张国伟等, 2004) ...

2013

0.0

... 区域内构造活动强烈, 是南北地震带北段8级大地震最集中的区域, 地震灾害严重(张培震等, 2013) ...

2009

0.0

张培震, 闻学泽, 徐锡伟, 等. 2009. 2008年汶川8. 0级特大地震孕育和发生的多单元组合模式[J]. 科学通报, 54(7): 944—953.

ZHANG

Pei-zhen

, WEN

Xue-ze

, XU

Xi-wei

, et al. 2009. Tectonic model of the great Wenchuan earthquake of May 12, 2008, Sichuan[J]. Chinese Science Bulletin, 54(7): 944—953(in Chinese).

2008年5月12日四川省汶川县境内发生8.0级特大地震. 这次逆冲型地震发生在大陆内部的高角度逆冲断裂之上, 与有历史记载以来所发生的逆冲型特大地震是不同的. 通过对汶川地震的地表破裂、震源机制、余震定位、地震破裂过程、同震地壳形变、强地面运动等的综合研究, 认为汶川特大地震的孕育和发生是3个地质单元共同作用的结果. 川西高原作为变形单元震前发生长期持续的变形, 并且将变形转换为积累在龙门山断裂带的应力; 龙门山断裂带作为闭锁单元震前变形缓慢但积累很大的应力, 当其超过断裂的摩擦强度或岩体的破裂强度时就突发破裂, 形成地震, 释放出巨大的能量; 四川盆地作为支撑单元对川西高原和龙门山的向东运动产生阻挡, 是汶川地震孕育不可缺少的元素. 汶川地震的孕育和发生可以用多单元组合模型来理解.

... 0地震(张培震等, 2009 ...

2016

0.0

郑文俊, 袁道阳, 张培震, 等. 2016. 青藏高原东北缘活动构造几何图像、运动转换与高原扩展[J]. 第四纪研究, 36(4): 775—788.

ZHENG

Wen-jun

, YUAN

Dao-yang

, ZHANG

Pei-zhen

, et al. 2016. Tectonic geometry and kinematic dissipation of the active faults in the northeastern Tibetan plateau and their implications for understand ing northeastward growth of the plateau[J]. Quaternary Sciences, 36(4): 775—788(in Chinese).

Available studies suggested that the northeastern Tibetan Plateau is the growing and expanding frontier following the India-Eurasia collision. Cenozoic deformation due to the continuous India-Eurasia collision has been the driver for the landscape evolution of the NE Tibetan Plateau. During recent decades, both the international and domestic efforts on large-scale active fault mapping collected plenty of basic information and data to understand the deformation pattern. Numerous results from studies related to active faults and folds, Cenozoic basin sediments and geodesy observations help our new insights into the geological history of this growing plateau. The Late Quaternary geometry and kinematics of the northeastern Tibetan Plateau are characterized by three groups of active faults of different strikes: the EW-NEE trending left-lateral strike-slip faults, NWW striking thrust faults and NNW trending right-lateral strike-slip faults. Among of them, the dominated left-lateral strike-slip faults are major structures in transferring deformation in this region; the thrusts are mainly developed at the tips of the strike-slip faults, absorbing and dissipating the lateral strike slip rate along the boundary strike-slip fault; the right-lateral strike-slip faults developed in southern Qilian Shan mainly accommodated the relative motion between active blocks. These three groups of active faults indicate the outward and growth process of the Tibetan Plateau. The Qilian-Haiyuan Fault and Altyn-Tagh Fault both contribute to the adjustment and transformation of the strain, and indicate a continuous deformation pattern of the NE Tibetan Plateau. Deformation near the ends of these two faults were being absorbed by the thrust and shortening within the Qilian Shan and Liupan Shan, respectively. In the northeastern margin, the Tibetan Plateau was observed to be progressively growing following the uplift of the Qilian Shan from south to north. The deformation has extended into the southern margin of the Gobi Alashan block across the Hexi Corridor in Late Cenozoic. In the northeastern margin, the Sanguankou-Niushoushan Fault zone located to the northeast of the Haiyuan Fault, is the youngest boundary between the Tibetan Plateau and the Ordos block, indicating that the deformation has extended from the Haiyuan Fault to the further northeastern direction progressively.

1. State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029; 2. Lanzhou Institute of Seismology, China Earthquake Administration, Lanzhou 730000; 3. School of Earth Science and Geological Engineering, Sun Yat-Sen University, Guangzhou 510275; 4. Earthquake Administration of Ningxia Hui Autonomous Region, Yinchuan 750001

基于近十几年以来青藏高原东北缘活动构造运动特征调查与定量研究结果，在总结区域活动构造运动特征基础上，指出青藏高原东北缘发育有近东西-北东东向的大型左旋走滑断裂带（祁连-海原断裂、阿尔金断裂等）、北西西向的逆冲断裂带（祁连山内部及边缘断裂、河西走廊内部及边缘断裂和六盘山断裂等）和北北西向的右旋走滑断裂带（主要是鄂拉山断裂与拉脊山断裂）3组不同方向以及不同运动性质的活动断裂，它们共同控制着青藏高原东北缘的活动构造几何图像和运动转换；其中，大型左旋走滑断裂在区域构造运动转换过程中起着控制性作用，逆冲断裂一般发育在大型走滑断裂的端部，起着调节和吸收大型走滑断裂端部水平滑动的作用，而祁连山南部右旋走滑断裂主要是对不同块体差异运动过程进行调节。结合区域新构造变形的研究结果，认为青藏高原东北缘不同方向和性质活动构造的发育、形成、生长以及扩展过程，控制着高原东北缘构造变形和演化的历史；高原东北缘由南向北逐渐扩展，逐步形成了青藏高原东北缘的现今构造格架，而高原东北缘新活动边界在新生代晚期已越过河西走廊到达阿拉善地块南缘，同时在东北缘弧形构造带的位置也已形成了以三关口-牛首山断裂带为主的高原隆升和向外扩展的新边界。

... 郑文俊等, 2016 ...

2017

0.0

... 朱介寿等, 2017), 设定通道厚度h为20km, 并假定黏滞系数在同一剖面并不随空间距离而变化 ...

1993

0.0

... Avouac et al ...

2011

0.0

... , 2010), 还是利用区域地震衰减层析成像(Bao et al ...

2001

0.0

... Beaumont et al ...

1991

0.0

... , 1986)与地壳流模型(Bird, 1991 ...

... Bird, 1991 ...

... 侧向压力梯度是由地壳内部的厚度或密度不均而引起的, 而在下地壳足够弱的情况下, 它将通过下地壳管道流动而变形(Bird, 1991 ...

1990

0.0

... , 1996), 因此下地壳弱黏性层能够在地质时间尺度上流动(Block et al ...

... Block et al ...

1999

0.0

... Bott, 1999 ...

1980

0.0

... Brace et al ...

1994

0.0

... 差异地貌明显, 多以深大断裂为边界, 例如西秦岭北缘断裂为西秦岭和陇西盆地的宏观地貌边界, 龙门山断裂、虎牙断裂为松潘构造结与四川盆地的边界(Chen et al ...

2005

0.0

... , 2000, 2005 ...

2000

0.0

... Clark et al ...

... 下地壳流变学在控制地壳形变方面发挥着重要作用, 估算下地壳的流变参数可以探索构造变形与地形之间的关系(Clark et al ...

... 2)通过地形地貌解析方法, 以物理学概念中的流体力学理论获得黏滞系数(Clark et al ...

... 1 下地壳管道流模型Clark等(2000)提出的下地壳管道流模型将下地壳看作一个厚度均匀的通道, 在这个通道中地壳物质可随着横向压力梯度变化而流动, 进而引起地形变化 ...

... Clark et al ...

... Clark等(2000)与Wang等(1998)均认为最大地形包络线是先前抬升面在现今的高程位置, 因此本文选取新生代造山带的最大高程点与区域地形的最低点作为图 3 中各个剖面拟合红线的起点和终点, 以约束下地壳黏滞系数 ...

... Clark et al ...

... 另外, 前人的研究或囊括了整个青藏高原(Clark et al ...

2018

0.0

... Diao et al ...

... 0地震后, 国内研究者开始对2次地震的震后形变过程开展深部流变学参数研究(Diao et al ...

1982

0.0

... , 1993)、连续变形模型(England et al ...

1985

0.0

... , 1982, 1985, 1986 ...

1986

0.0

... , 1982, 1985, 1986 ...

1979

0.0

... 同时, 许多研究人员通过岩石力学实验预测中地壳或下地壳可能存在弱黏性区, 将其与脆性的上地壳分开(Goetze et al ...

1992

0.0

... 前人的研究(Harrison et al ...

1986

0.0

... Houseman et al ...

2000

0.0

... 中下地壳低黏度层的存在也得到了高原区域下方高温流(Hu et al ...

1994

0.0

... Kirby, 1983), 并且许多地球物理学观测结果也表明地壳存在黏滞性(Jin et al ...

1983

0.0

... Kirby, 1983), 并且许多地球物理学观测结果也表明地壳存在黏滞性(Jin et al ...

1991

0.0

... Kruse et al ...

1975

0.0

... 约45Ma BP以来, 印度与欧亚大陆的碰撞导致了喜马拉雅山脉的迅速隆起以及地势高但地形起伏并不大的中央高原的发展(Le Fort, 1975 ...

2007

0.0

... , 2012)以及碎屑锆石U-Pb年代学研究(Lease et al ...

2015

0.0

... 虽然青藏高原东北部(特别是西秦岭-松潘构造结附近)与喜马拉雅山脉不同, 其没有足够的结构、变质、温度测量和地质年代学数据等下地壳流模型的证据(Searle, 2015), 但在地震学领域, 无论是利用接收函数方法(Liu et al ...

1996

0.0

... Makovsky et al ...

1991

0.0

... Marquart, 1991 ...

2000

0.0

... McQuarrie et al ...

1975

0.0

... 1 区域概况新生代以来, 印度板块向欧亚板块俯冲碰撞导致青藏高原快速隆升、高原周边强烈变形, 形成现今高原内部和周边的地貌格局(Molnar et al ...

... Molnar et al ...

1996

0.0

... Nelson et al ...

... , 2000)、高反射体和高导电体(Nelson et al ...

2013

0.0

... 南侧主要发育了东昆仑尾端帚状散开的弧形构造系, 包括龙日坝断裂、岷江断裂和虎牙断裂等(Ren et al ...

2018

0.0

... 5级地震(Ren et al ...

1996

0.0

... Royden, 1996 ...

1997

0.0

... Royden et al ...

2011

0.0

... , 2007, 2010, 2011 ...

... Ryder等(2011)使用Burger体流变学模型对2001年M_W7 ...

2010

0.0

... , 2007, 2010, 2011 ...

... Ryder等(2010)等对西藏改则地震的震后余滑进行了研究, 取中#cod#x02014 ...

2007

0.0

... 目前, 估算黏滞系数主要有2种方法: 1)通过GPS及InSAR等大地测量方法观测震后形变以求得黏滞系数(Ryder et al ...

... Ryder等(2007)在研究玛尼地震时给出的黏滞系数为4#cod#x000D7 ...

1990

0.0

... Schmeling et al ...

2015

0.0

1986

0.0

... 压力驱动下的流动可使上、下地壳存在差异性增厚现象, 并且可能在超过100km的距离内进行地壳的长距离转移(Synder et al ...

1976

0.0

... 0 引言20世纪80年代以来, 大量研究者给出了青藏高原不同的变形模式, 主要有刚性块体模型(Tapponnier et al ...

1982

0.0

... , 1976, 1982 ...

2018

0.0

... Tian et al ...

1998

0.0

1992

0.0

... Wdowinski et al ...

1998

0.0

... Wessel等(1998)提供了GMT软件 ...

2013

0.0

... 1 西秦岭-松潘构造结及邻区的下地壳黏滞系数西秦岭-松潘构造结南部为松潘-甘孜地块, Xie等(2013)通过地震学研究认为其下地壳处于部分熔融状态, 平均海拔为4~5km, 与周围山体的高差不大, 而下地壳黏滞系数的估计主要考虑研究区内最高、最低点的海拔高度及其之间的距离等构成曲线的参数 ...

2012

0.0

... Yang et al ...

2010

0.0

... , 2015)、环境噪声层析成像(Yang et al ...

2013

0.0

... 其次, 据Yuan等(2013)的研究结果可知, 约15Ma BP以来青藏高原东北缘NE-SW向甚至ENE-WSW向加速缩短变形, 模拟剖面D#cod#x02014 ...

2012

0.0

... 首先, 对于共和盆地、循化盆地及贵德盆地附近的青海南山和拉脊山等山系, 根据前人利用地磁地层学(Zhang et al ...

... 共和盆地附近的青海南山和拉脊山等山系在6~10Ma BP开始隆升(Zhang et al ...

2004

0.0

... 同时, 在地形地貌方面, 前人的研究并未过多指出高程等高线呈椭圆形, 而椭圆形的地貌形态进一步说明青藏高原的形成演化过程具有流变特性, 也符合Zhang等(2004)提出的连续形变的模式, 未来值得针对此地区进行进一步研究与讨论 ...

2013

0.0

... Zhang, 2013)、 186BC武都7~71/4级地震(袁道阳等, 2007a)、 1976年松潘7 ...

2010

0.0

... 根据地震学及大地电磁数据获得的中下地壳中低速、低阻的软弱层结果(Zhang et al ...