岩石圈塑性流动与大陆板内构造变形研究进展评述

人们对大陆板内构造变形机制有两种不同认识,即“刚性”板块通过弹性实现应力远程传递和岩石圈通过下层塑性流动实现应力远程传递。通过对岩石圈各层变形属性和塑性流动的研究。认为通过处于塑性状态的下地壳和岩石圈地幔的塑性流动实现应力远程传递和控制板内构造变形更为合理。     

中东亚大陆塑性流动网络控制下构造变形的物理模拟

以塑化松香和干凝滑石粉浆分别作为岩石圈延性下层（下地壳及岩石圈地幔）和脆性上层（上部地壳）的相似材料,就亚洲中东部大陆在板块边界推挤作用下的构造变形进行了模拟实验。初步结果表明,本地区在印度板块和菲律宾海板块的推挤下,形成两个塑性流动网络系统,它们控制了岩石圈上层构造变形,在分布格局上大致与地震的网络状分布相对应;东北部可能存在另一规模较小、作用较弱的驱动边界及相应的网络系统,由于它的影响,导致华北北部构造带和地震带的扭曲。实验还表明,大型压性盆地的形成与岩石圈下层稳定块体的存在有关     

岩石圈塑性流动波的实验研究(Ⅱ)

岩石圈塑性流动波的物理模拟实验表明 ,在板块边界驱动下 ,模型中除了产生“快波”(波速量级大致相当于原型的 10 0 ～ 10 2 km/a)外 ,还存在着相当于原型波速量级为 10 - 1～ 10 0 m/a的“慢波”。“慢波”也可分解为主波和辅波 ,主波类似于涌波 (孤立波 ) ,辅波则以波群的方式传播 ,二者均系粘性重力波。板块边界的驱动作用通过不同波速的多重塑性流动波向板内传播 ,控制地震能量背景的起伏振荡 ,并导致缓慢构造运动的韵律性变化     

岩石圈塑性流动波的实验研究(Ⅰ)

实验采用了适当配比的塑化松香 ,模拟岩石圈延性层 ,研究边界驱动条件下塑性流动波的传播过程。实验表明 ,塑性流动波类似于粘性重力波 ,并有“快波”和“慢波”之分 ,二者分别由主波和辅波叠加而成。主波类似于孤立波或涌波。根据相似原理 ,“快波”主波的外推波速约为 0 .12～2 .5km/a ,在波速量级上大致相当或接近于岩石圈下层某些控制地震迁移的塑性流动波     

青藏高原岩石圈多层构造应力场

青藏高原构造应力场可按岩石圈下层、多震层和浅层地壳区分为三层。除了震源机制解方法和井孔原地测量方法可分别用于推测多震层和浅层的应力状况外,还可根据下层塑性流动网络,采用平分网络共轭角的方法估计下层的应力方向。对比岩石圈下层与上层(多震层)的构造应力场,其结果表明: 由于板块边缘驱动力主要通过下层的网络状流动实现其远程传递,故在总体作用趋势上,上层的应力方向受控于下层;又由于高原靠近喜马拉雅驱动边界,部分驱动力直接沿上层传递,致使局部地区上、下层应力方向相差显著。     

大陆岩石圈塑性流动网络的延性弱面效应

岩石圈下层的网状塑性流动 ,作为包含塑性流动网络的黏塑性流动 ,控制着大陆板块内部的构造变形和动力学过程。塑性流动网络由两组网带共轭相交而成 ,而塑性流动网带是黏塑性流动过程中因剪切局部化、黏性摩擦生热和网带介质的弱化而形成的延性弱面 (弱带 )。研究表明 ,类似于断裂和节理等脆性弱面 ,延性弱面对介质强度的影响也具有条件性 ,即当应力方向改变时 ,只有在滑移角θ不超出一定限值的条件 (θ1≤θ≤θ2 )下才可能沿原有弱面滑移 ,显示其弱化效应 ;延性弱面可以用弱化度R表示其屈服限的相对降低程度 ,弱化度与滑移角下限值之间的关系为R =sin2θ1;根据亚洲中东部地区“塑性流动 -地震”网络的最大共轭角推算 ,网带的弱化度R近似于 0 81。基于延性弱面效应的认识 ,文中就网带由剪切滑移向压性褶皱的转化、网带的继承与弃置以及应力方向的允许偏角等问题进行了探讨     

岩石的脆性-延性转变及塑性流动网络

实验变形研究表明.随着矿物组成.粒度、温度、围压、应变率、液体介质等因素的变化岩石由脆性,半脆性,向半延性.延性转变,其中包括力学行为.微观机制和宏观结构的变化,而决定岩石脆性-延性转变的基本因素在于所含的粘塑性成分及其粘滞性.半延性流动具有共轭网络状的结构特征;延性流动则包括网络状流动和均匀流动两种宏观结构;半延性-延性流动网络以其近似正交性和非牛顿流动特性分别与半脆性破裂网络和均匀延性流动相区别.基于上述研究,可将地壳、上地幔划分为脆性-半脆性的中上地壳,半延性-延性网络状流动的岩石圈下层(含下地壳和岩石圈地幔)和均匀延性流动的软流圈.地壳多震层内的大型地震带及网络是岩石圈下层塑性流动网络的一种响应.     

岩石圈下层塑性流动网带的剪切热效应

基于“网状塑性流动”大陆动力学模型和中国大陆大地热流的分布特征,文中针对网带黏性剪切热效应的平衡态,通过热力学能量方程的求解,导出网带温度异常方程等关系式,并通过与网带热流正异常的拟合分析,确定了相关的参数值。研究表明,塑性流动网带黏性剪切热的产生为温度的正异常提供了热源,并通过热传导扩展网带的影响范围,形成相应的热异常网带。作为对中东亚塑性流动网络系统平均状况的估计,网带的热异常宽度与地震带所显示的网带视宽度一致,约为65km;剪切网带的宽度为44km,约为网带热异常宽度的23;网带中线处的温度正异常约为210K,剪切网带边界处的温度正异常约为67K,至热异常带边缘处降低为零,其起伏形态与网带大地热流正异常“凸峰”相一致。文中为岩石圈下层塑性流动网络的存在及其对大地热流正异常分布的控制提供了理论依据     

塑性流动网络控制下华北地区构造应力场与地震构造

文中所述华北地区位于中东亚塑性流动网络系统的东部 (偏北 ) ,在岩石圈下层内含右向和左向塑性流动网带多条 ,受其控制 ,在其上方多震层内形成地震带 ,并导致上层构造应力场在总趋势上与下层基本保持一致。发震断裂以不同交角沿网带展布 ,组成地震构造带 ,其中少数地震构造带的视成熟度较高 ,多数尚属未成熟的准地震构造带     

中国东南地区塑性流动波与地震迁移(Ⅱ)

由文 (Ⅰ ) (王绳祖等 ,2 0 0 3)已知 ,受网络波的控制 ,地震活动主要发生在能量相对聚集的波峰带内。文中根据地震释放的能量分布状况 ,进一步分析了能量沿波峰带法向的分布以及随传播距离的衰减 ,并基于发震概率与背景能量之间的对应关系 ,估计发震概率的分布状况。以此作为地震能量背景的概率表达和地震预测的依据之一 ,给出了中国东南地区与能量背景相关的发震概率分布图     

地球岩石圈和软流圈结构的3—D模拟

本文介绍国际岩石圈计划Ⅱ－４任务组关于地球岩石圈和软流圈结构多学科３－Ｄ模拟的基本研究思路和具体研究步骤,并概略介绍了结构数据库的建设和改进。     

上部岩石圈应力状态的三维有限元模拟

本文较详细地介绍了上部岩石圈应力状态的三维有限元模拟的方法及得到的垂直应力特征。假设在地质时间尺度上,上部岩石圈0～40公里范围内(简称地壳)以线弹性变形为主。考虑到地壳三维不均一性对地壳应力场的影响,将地壳沿水平方向分成七种地质构造单元:大洋、大陆、高原、洋中脊、海沟、转换断层和三联点,沿径向方向分成二层,以重力(包括引力和离心惯性力)和温度变化作为载荷,采用三维有限单元法计算了地壳的应力场。计算结果表明:(1)地壳垂直应力以压应力占绝对优势,张应力只发生在洋中脊等异常带及其它特定地区,(2)在同一深度上,垂直应力随纬度的增大而线性增加,(3)在深25公里范围内,垂直应力随着深度的增加而增大,其值与海姆法则预测值吻合;(4)异常高的垂直应力梯度往往发生在异常带(板块边界)邻近地区。     

Lanzarote火山与地球动力学实验场的地壳变形、地热流动态监测研究

主要介绍中国、西班牙两国在Lanzarote火山与地球动力学实验场 12年的合作监测研究。1991年以来 ,中西双方共同在Lanzarote岛火山活动地区建立了Cueva和Timanfaya 2个监测站 ,进行地壳变动和地热流动态监测研究。对合作研制的 2 9台 (套 )监测仪器开展长期稳定实验 ,积累了大量观测资料和数据。初步分析表明 :仪器运行良好 ,记录长期稳定可靠 ;Cueva站的仪器记录主要反映区域或全球地球物理环境或动力学效应 (如海潮、固体潮等 ) ,应变潮汐和倾斜潮汐的O1波、M2 波具有较高精度 ,显示火山目前活动微弱 ;Timanfaya站的仪器记录主要反映局部的火山活动信息 ,显示火山仍在活动但呈下降趋势。为今后火山喷发演变过程的监测研究和进一步合作奠定了基础     

上地幔物质运移与地壳形变

本文据根GEM 10 B地球模型计算得到的卫星自由空间重力异常,分析了上地幔物质流运移的动力学关系。对在青藏高原上地壳的楔入作用影响下,上地幔物质流的运移状态及所造成的地壳形变进行了讨论。并对中国西南部壳体强烈的地壳形变以及频繁的地震活动的力源机制问题进行了探讨。     

亚洲中东部岩浆岩网络状分布与塑性流动网络

亚洲中东部的岩浆岩分布具有明显的网络状特征，共轭相交的岩浆岩带构成了晚古生代、中生代和新生代不同的岩浆岩网络系统。岩浆岩网络受岩石圈下层塑性流动网络的控制，是塑性流动带剪切变形、摩擦热效应及带内介质弱化、轻化，以至促成地幔上隆和岩浆上涌的结果。根据“塑性流动－岩浆岩”网络，推测了不同地质时期大陆构造变形的驱动边界、驱动力方向和古构造应力场，并探讨了网络构造的演变等问题     

断裂带中的二相变形与地震成因讨论

本文主要以郯庐断裂带现代侵蚀面上五种不同类型的断裂构造和断层岩石为例,论述大断层带中岩石变形的二相性特征,包括机械意义的“韧性相”和“脆性相”应变组分在变形过程中的作用和意义。在此基础上探讨一种可能的地震成因方式     

室内构造变形物理场观测系统的设计与实施

建立一个完整配套的室内地震预报实验场观测系统是深入进行地震预报理论研究，提高物理预报准确率，检验各种预报方法的重要手段。为此，设计试制了一套多通道、高分辨率、宽动态、宽频带的数字化实验观测系统。该系统可以联接多种传感器，用于多参数物理场的同步动态观测     

THE DEFORMATION OF THE 2008 ZHONGBA EARTHQUAKES AND THE TECTONIC MOVEMENT REVEALED

On August 25, 2008, an M_W6.7 earthquake struck Zhongba County, central Lhasa block. Subsequently, an aftershock of M_W6.0 occurred on September 25. The rupture caused by this earthquake is rather complicated. There are some differences in focal positions and fault parameters given by different institutions. In addition, a deeper understanding of the tectonic significance of this earthquake is also needed. Firstly, we use interferometric synthetic aperture radar data collected by the environmental satellite(ENVISAT)of European Space Agency and the advanced land observing satellite(ALOS)of Japan Aerospace Exploration Agency to obtain eight coseismic deformation fields covering the whole epicenter region based on InSAR technology. Because the terrain in the earthquake area fluctuates greatly and there are many objects with low coherence(eg. lake), we choose 30-resolution SRTM DEM data as reference DEM, the more robust Goldstein as filtering method, and Delaunay Minimum Cost Flow as phase unwrapping method. The interferograms show that the surface deformation caused by this earthquake is about 50km long and is divided into two lobes, north and south. The shape of the deformation in the north is similar to that of Palung Co Lake, and the maximum signal is hidden by the lake. The deformation in the south has two centers, located at two ridges respectively. The aftershock also caused two minor deformations at the east and north of Palung Co Lake. Secondly, we use uniform sampling method to downsample 8 interferograms, and set the sampling interval of near-field data to be much smaller than that of far-field region, to ensure the observation data characteristic and sampling density of the main deformation region. In order to better invert the rupture slip distribution of the main shock, we subtract the influence of aftershock deformation. Finally, 6 data sets for the main shock deformation are obtained. Smoothness of sliding distribution is applied to restrict the sliding amount of adjacent fault slices. The best-fit solution shows that at least two ruptures in the south and north are caused by the earthquake, mainly of normal dip-slip and partial sinistral strike-slip by Okada uniform elastic half-space dislocation model and SDM method. The northern rupture is related to the Palung Co Fault with NE strike, with the maximum deformation of -13.0cm and the maximum slip of 0.52m in the depth of~12km, and the southern rupture deformation is obviously strongly related to topography, with the maximum deformation of -38.7cm and the maximum slip of 1.15m in the depth of~14km. The maximum slip is located at(30.81°N, 83.45°E), between the positions determined by GCMT and NEIC. The results also show that normal fault earthquakes may play an important role in the uplift of Tibet Plateau. Thirdly, we use 15 images obtained between 2008 and 2010 from ENVISAT to obtain the post-earthquake time series deformation to further understand the tectonic background of the earthquake using SBAS-InSAR technology. 54 pairs of good interferences are screened out for processing, of which 30 pairs were unwrapped by Delaunay MCF method. The velocity accuracy threshold is set to 2mm/a to ensure reliable estimation of deformation velocity value. After two step SBAS inversions, the time series of deformation after the earthquake is obtained, thereby revealing that the post-earthquake deformation is not obvious on both sides of the fault but in the denudation and deposition area. This shows that no obvious common phenomena such as afterslip or creep are found after the earthquake. From the three cumulative deformation profiles, it can be seen that the regional deformation is mainly denudation and subsidence related to topography and geomorphology, and the deformations of adjacent subsidence and uplift regions are basically the same. The result shows that the graben structure in Lhasa block is mainly vertical deformation caused by terrain difference. In order to explain this result, we processed GPS data from 1991 to 2015 and obtained the principal strain rate in the western region of Lhasa block. The result shows that the east-west extension in Lhasa block is obvious but uneven. The strain is mainly stretching or squeezing perpendicular to deep and large faults, and the strain decreases near the grabens. The tensile strain near the Palung Co fault graben is~2.4×10⁸/a. This also shows that estimates of the tectonic activity based on geomorphology may be underestimated on some normal faults that have not been mapped or have no clear large-scale surface expression in the Tibet Plateau. This study combines multi-orbit InSAR data to constrain the focal mechanism solution of the Zhongba earthquake, proving that abundant interferometric results can complement each other, which is helpful to analyze the deformation distribution caused by the earthquake more clearly and completely, especially in the absence of surface rupture.