The Baikal Rift and the Fenwei Graben are two famous rift systems located in the eastern Eurasian plate, with similar topographic features and geomorphic characteristics. Their tectonic evolution histories are also similar. Many studies have shown that their formation is closely related to the Indo-Eurasian collision, however, the mechanism for this long-range effect is not clear. In this paper, basing on the evolution of extensional tectonics caused by mantle upwelling in the continental margin during the continental drift and continental margin splitting, combined with the Cenozoic tectonic evolution of Eurasia, we studied the evolution of microcontinental fragments and extensional tectonics under the long-range effect. The results show that the origin of the two rift systems is closely related to the Cenozoic large-scale fragmentation and drift of microcontinents in the eastern margin of the Eurasian. Briefly, the Qinghai-Tibet Plateau uplift results in large-scale mantle upwelling and continental breakup in the Cenozoic, where the breakup and drift of the proto-Japan/proto-Kamchatka blocks form a differential sinistral strike-slip environment, and lead to the formation of the two rift systems in two seismic zones on the southeast side of the Siberian and Ordos Basins. These two seismic zones, which have similar genetic mechanisms to the Türkiye earthquake in February 2023, are formed by strike slip faults, and their genetic mechanisms can be reasonably explained by the new continent drift model.

The formation and evolution of the South China Sea has been widely studied.More than five genetic models have been proposed.The current popular model is seafloor spreading,but it is difficult to reasonably explain the mid-ocean ridge jumping in South China Sea and the continental fragments found in the central basin of the South China Sea.First,based on two high precision seismic exploration sections in the central basin of the South China Sea,a new tectonic geological interpretation of the two seismic exploration sections was given on the basis of in-depth analysis of the layered structure of the oceanic crust.Then,through the formation process of extensional tectonics,the model of continental drift driven by mantle upwelling and continental crust gravity slip was developed.Finally,the formation and evolution process of the South China Sea was deeply studied.The results show that the formation of the South China Sea is a"tectonic extrusion+active drift"model.Tectonic extrusion is a large-scale passive extrusion of the microcontinents in the southeast margin of Eurasia plate caused by the India-Eurasia collision,while active drift is the active drift of the microcontinents after extrusion.The residual seismic reflection in the central basin of the South China Sea is a phenomenon of seafloor spreading caused by active drift of microcontinents.Furthermore,the geotectonic evolution of the microcontinents surrounding South China Sea was restored.The proposed new model can reasonably explain the phenomenon of mid-ocean ridge jumping in the South China Sea and the genetic mechanism of continental debris.The proposed new continent drift model provides a new dynamic model for plate movement.

南大西洋裂解造成的非洲和南美洲的大陆分离得到了广泛认可,该区域也与大陆漂移学说的诞生密切相关.但大陆漂移的驱动力从其提出至今一直存在争议,定量化分析大西洋裂解过程中板块运动的驱动力显得尤为重要.我们研究了南大西洋两侧被动大陆边缘盆地区域的两条深反射地震勘探剖面,在构造地质解译基础上,详细估算了非洲大陆的莫霍面倾角,得到了沿莫霍面地壳重力滑移剪切力的大小,用于解释大西洋裂解过程中非洲大陆运动的动力机制.结果 说明,非洲大陆板块在地幔上涌形成的倾斜界面上能够产生强大的重力滑移力,且南部驱动力大于中部.大陆板块依靠连续的地幔热上涌和重力滑移力会持续漂移.该模型能够合理解释大西洋上诸多线状分布的大陆残片的成因机制,也能合理解释南大西洋南部宽度大于中部的内在原因,最后对南大西洋的打开过程进行了精细的构造演化史恢复.该研究为板块运动提供了一个新的动力模式,为认识板块运动驱动力提供了更为精确的约束信息.

"构造变形岩相"填图方法的创立和应用为老矿区深部及外围的找矿工作指明了方向,在实践中取得了显著的效果,需要大力推广和深入研究.对于构造变形岩相带的深部结构认识,需要依靠地球物理信息的解译.与地球物理场性质相类似,构造变形岩相带也是一个现存的地质体;物探工作目的 是要探测和揭示构造变形岩相带的埋深、轮廓、内部结构构造等特征,为确定其形成时间和演化过程提供依据.由于地质与地球物理的复杂时空关系,如果仅以新鲜岩石标本物性参数的差异作为判别标志,难以提高地球物理方法的分辨率和有效性.结合构造变形岩相进行综合解译,更能提高解释推断成果的多学科融合性.作为终极勘探目标,需要紧密结合构造控矿级序,建立构造变形岩相带的三级分类标准,提取对应的地球物理信息:一级构造变形岩相带为目标物所处的构造单元及构造应力场,及其所对应的区域地球物理场特征,如隆凹构造相间的伸展构造域;二级构造变形岩相带为目标物所处的控矿构造体系,及其所对应的矿田地球物理场特征,如岩浆核杂岩隆起-拆离构造系统;三级构造变形岩相带为目标物所在的有利成矿构造部位,及其所对应于关键剖面的地球物理特征,如侵入岩体与围岩的接触带或者含矿断裂带等.选择国际流行的典型金属矿床类型,介绍了三级构造变形岩相带的地球物理组合信息特征及其分级利用操作流程,为有效应用地球物理勘探方法开展深部找矿预测提供了范例.

呵叻盆地是特提斯成矿带重要的钾盐成矿盆地,但是其变形构造与钾盐分布规律不清而严重制约了该区域钾盐矿床的勘探与开发.在宏观区域大地构造演化分析基础上,以老挝万象凹陷中一个区块为例,实施了三维地震勘探,在高精度地震资料和钻井自然伽马测井严格约束下,得到了地下准确的构造变化和钾盐矿分布资料.结合盐构造变形特征和地震勘探剖面进行了地质解译,结果显示印支地块的挤压走滑旋转对呵叻盆地内的钾盐矿进行了强烈改造,由此总结出三种钾盐矿改造模式,分别为蒸发岩侏罗山式褶皱变形模式、应力作用下的差异载荷富集模式和围绕硬质盐丘旋转的富集模式.

位于青藏高原腹地的羌塘盆地是我国最大的中生代海相含油气盆地,盆地发育多套生储盖组合,其中蒸发岩的膏盐层往往作为油气藏研究的盖层.但盆地内蒸发岩大多只达到硫酸盐沉积阶段,盆地内是否存在古钾盐矿?最佳的钾盐矿成矿有利区域具体位于何处?保存的远景资源量有多少?通过青藏高原形成过程中微地块的碰撞和拼合历史.研究羌塘盆地中生代沉积和演化过程,厘清羌塘盆地钾盐主要富集在中生代侏罗系的局限台地相区域.结合地震勘探和构造演化史恢复,阐明只有在逆冲推覆构造之下的区域才可能保存钾盐矿.根据羌塘盆地侏罗系夏里组沉积相带分布范围,推测保存钾盐矿的两个有利区主要位于安多县北西方向,面积约8000 km2.综合地表膏盐层分布和地球物理勘探推断的羌塘盆地中侏罗统石膏层厚度分布图,根据海水中析出石膏和钾盐的比例,结合推覆构造对侏罗系夏里组的保存比例,推测羌塘盆地保存的钾盐资源量约为11亿吨.

Based on the physical parameters of the rocks (ores) and the genetic types of ore deposits, the geophysical exploration models have met issues of multiple solutions for deep prospecting prediction. It is necessary to find recognizable geological targets with high precision by geophysical methods. The ore prospecting practice over past years has demonstrated that the ore field tectonic deformation lithofacies belt is an outstanding target and significant prospecting results have been achieved. At present, the geophysical exploration work of large-scale mining area is heavy, while that of medium-scale ore field is limited, and both of them lack the strategic guidance at different levels. In order to establish the geophysical identification mark of the tectonic deformation lithofacies belt in ore field, it is necessary to clarify the complex time-space relationship between geology and geophysics, and strengthen the connection between geomechanics and geophysical exploration methods. In this paper, a method of processing and interpreting geophysical information at different levels is proposed. According to the "✳-shaped" structural features of the tectonic traces in the study area and the characteristics of the periodic development of the tectonic system, the geophysical exploration data of different scales and dimensions are analyzed from the two levels of ore field and deposit, and the information of tectonic deformation lithofacies belts is extracted. The specific operation procedures are as follows: (1) Making an area geophysical exploration within the scope of the ore field, interpreting the "✳-shaped" fault structure system, and then selecting the tensional and tension-torsional ore-bearing fault structures and predicting the prospecting direction; (2) Laying out large-deep geophysical profiles in the ore-bearing fault zone, analyzing the denudation degree and burial depth, and delineating the location of prospecting targets based on the geochemical exploration information. The application results of this method in the Chaihulanzi gold field in Chifeng, Inner Mongolia is introduced. The "✳-shaped" distribution of structural traces of the Neocathaysian tectonic system are interpreted from the geophysical data of the ore field, and then it is confirmed that the NNW and NWW trending tectonic deformation lithofacies belts are the main ore-bearing structural belts and there is a spatio-temporal sequential relationship between them in the two mining areas. These findings, provides a basis for deep ore prospecting and prediction.

基于岩(矿)石物性参数和矿床成因类型建立的地球物理勘查模型,在深部找矿预测中出现了多解性的问题,急需找到地球物理方法能够高精度识别的地质体目标.多年的找矿实践表明,矿田构造变形岩相带就是一个重要的选项,业已取得显著的找矿效果.目前,大比例尺的矿区地球物理勘查工作较多,而中比例尺的矿田地球物理研究比较薄弱,且两者均缺乏分层次的战略指导.为了建立矿田构造变形岩相带的地球物理判别标志,需要厘清地质与地球物理的复杂时间-空间关系,加强地质力学与地球物理勘探方法的联系.文章提出分层次处理和解释地球物理信息的思路,即根据研究区构造形迹的"米字型"结构特征和构造体系阶段性发展的特点,从矿田、 矿床2个层次解析不同尺度-维度的地球物理勘查资料,提取构造变形岩相带信息.具体操作流程为先在矿田范围内布置面积性物探,解译"米字型"断裂构造系统,选定张性和张扭性含矿断裂构造,预测找矿方向;再在含矿断裂带布置大深度物探剖面,分析剥蚀程度和埋藏深度,结合化探信息圈定找矿靶区位置.文中以内蒙古赤峰柴胡栏子金矿田为例,介绍该方法的找矿应用效果.首先从矿田地球物理资料中解译出新华夏构造体系"米字型"分布的构造形迹,然后在2个矿区内确认了北北西和北西西走向的构造变形岩相带是主要的含矿构造带,且两者之间存在时空上的先后关系,为深部找矿预测提供了依据.

It has important theoretical and practical significance to clarify the causes and distribution of oil and gas. This paper focused on the key scientific issues in the current petroleum genesis research, guided by the general principles of global tectonics and petroleum geology. Various petroleum genesis hypotheses have been sorted out, merged, integrated and innovated, thus a hypothesis framework of organic-inorganic coupling causes for petroleum was introduced. The main factors are that oil (including natural gas) is a renewable resource with multiple origins and has huge reserves. The formation and distribution of petroleum is the result of the coupling of four pairs of hydrocarbon-forming factors, including basin and mantle uplift, deep and shallow fluids, organic and inorganic hydrocarbon generation mechanisms, deep faults and sealing conditions. The higher degree of organic-inorganic cause coupling indicates the richer the oil and gas. The basin and the area below its basement are the locations with the best degree of coupling, followed by the deep and large fault development areas with good sealing conditions in the surrounding areas of the basin. The matching of deep and large faults with sealing conditions is an important factor constraining hydrocarbon accumulation. Large-scale traps with good sealing conditions in long-term, multi-period or recent active deep and large fault development areas are the most favorable targets for major exploration successes.

钾盐是重要的工农业生产资料,虽然已经有诸多关于钾盐矿成因的研究,但关于大地构造运动与钾盐成矿的构造背景和成矿模式方面的研究还比较分散.本文首先从钾元素的初始成因出发,梳理出钾盐的物质来源.然后分别从钾盐矿形成的大地构造环境进一步分析在稳定克拉通环境、陆块汇聚环境和陆块裂解环境下的钾盐矿成矿过程,说明包括构造、物质来源和气候三要素都是大陆漂移和大地构造运动的结果.大地构造是钾盐矿形成的最为重要的因素,它控制了盆地的形成,也控制了钾盐的物质来源,还间接控制了蒸发岩沉积过程中陆块的空间位置和气候条件.最后通过印支地块中的呵叻盆地钾盐矿实例,给出了一个钾盐矿多级凹陷预富集成矿模式.结果说明大地构造运动是钾盐成矿的最主要控制因素.

我国缺钾严重,近年来钾盐对外依存度保持在50％左右,到钾资源丰富的国家建立自己的钾肥生产基地已成为保障我国农业安全的重要举措.我国虽有近10家企业在老挝投资钾盐勘探开发项目,但由于勘探阶段和开发阶段都存在着问题,经历了十多年的勘探开发仍未形成大规模量产.梳理了我国目前在老挝进行钾盐勘探开发的公司的简要情况,结合实例剖析了在老挝钾盐勘探开发过程中存在的问题,并总结了相应的经验教训.

The separation of P- and S-wavefields is considered to be an effective approach for eliminating wave-mode crosstalk in elastic reverse time migration (RTM). At present, the Helmholtz decomposition method is widely used for isotropic media. However, it tends to change the amplitudes and phases of the separated wavefields compared with the original wavefields. Other methods used to obtain pure P- and S-wavefields include the application of the elastic wave equations of the decoupled wavefields. To achieve high computational accuracy, staggered-grid finite-difference (FD) schemes are usually used to numerically solve the equations by introducing an additional stress variable. However, the computational cost of this method is high because a conventional hybrid wavefield (the P- and S-wavefields are mixed together) simulation must be created before the P- and S-wavefields can be calculated. We have developed the first-order particle velocity equations to reduce the computational cost. The equations can describe four types of particle-velocity wavefields: the vector P-wavefield, the scalar P-wavefield, the vector S-wavefield, and the vector S-wavefield rotated in the direction of the curl factor. Without introducing the stress variable, only the four types of particle velocity variables are used to construct the staggered-grid FD schemes; therefore, the computational cost is reduced. We also develop an algorithm to calculate the P and S propagation vectors using the four particle velocities, which is simpler than the Poynting vector. Finally, we apply the velocity equations and propagation vectors to elastic RTM and angle-domain common-image gather computations. These numerical examples illustrate the efficiency of our methods.

Full waveform inversion (FWI) is a non-linear inverse problem that can be sensitive to noise. The tolerance of the noise-interference characteristics depends on the types of misfit functions. To date, different misfit functions, such as the least-squares norm (L2), the least-absolute-value norm (L1), and combinations of the two (e.g., the Huber and hybrid criteria), have been applied to FWI. The L2 norm is highly sensitive to non-Gaussian errors in the data and gives rise to high-amplitude artifacts in reconstructed models. For non-Gaussian noise data, the L1 norm and the Huber and hybrid criteria always reliably reconstruct models. However, the Huber and hybrid criteria require tedious error investigations to estimate their threshold criterion. Thus, the L1 norm is adopted here to improve the anti-noise ability of the FWI. The step length is closely related to the misfit function, and an optimal step-length estimation method can rapidly make the FWI algorithm reach the global minimum, with a reduced number of iterations and fewer extra forward modeling simulations during each iteration. The step length can usually be obtained using the exact or inexact line search method. Generally, the exact line search method is faster than the inexact one. Therefore, we derived an exact line search method for the L1 norm in the FWI process. Its effectiveness was tested using noise-free data from Overthrust and the SEG/EAGE salt models. The results demonstrate that this method can recover high-resolution velocity models with low computational costs. Numerical tests using the synthetic Overthrust model contaminated by strong noise were used to further validate the robustness of this exact line search method.

日本列岛是位于欧亚东缘和西太平洋过渡带上的大陆板块,其来源和成因机制得到了广泛研究,传统上认为其成因是由太平洋俯冲形成的沟弧盆体系的一部分,但仍存在诸多争议.基于地形地貌、地震勘探剖面和盆地构造演化史恢复、古地磁测量和古生物等诸多证据,将南海北部的珠江口盆地、台西南盆地和东海盆地及冲绳海槽的构造迁移进行统一的系统分析,研究结果表明日本大陆板块在新生代由两个区域分别漂移 而来.北海道来自赤道附近,而本州、四国和九州来自华南大陆边缘.其成因动力机制与欧亚板块从北大西洋的裂解东漂和印度与欧亚碰撞密切相关,在这个过程中,位于欧亚板块东缘的日本三岛首先发生了裂解,之后发生了漂移.新的大陆漂移模型合理地解释了沟弧盆体系的形成机制和过程,说明了弧状岛弧的成因机制,也给出了所形成的盆地内油气富集的规律.本研究为大陆漂移模式提供了一个新的动力机制.

印度大陆板块是一个活化的克拉通板块,其向北漂移并与欧亚板块碰撞过程得到了广泛研究,但其北漂的动力机制则很少被关注.传统上认为是海底扩张造成了印度大陆板块的北漂,但最新的地球物理观测结果却与此相悖.基于地磁场异常特征、古地磁测量和地震勘探剖面等诸多证据的系统分析研究,结果表明印度大陆板块厚度大约40 km,其北漂的动力机制与印度板块南侧深部的岩浆上涌密切相关,大陆板块的漂移是自发驱动的.通过新建立的大陆漂移模型可以合理解释印度大陆板块漂移的动力来源,并合理地解释了印度大陆板块北漂中伴随左旋的深层次动力机制.最后探讨了印度大陆板块在80～40 Ma期间异常高速漂移的根源和东非大裂谷的成因.本研究为大陆漂移模式提供了一个新的动力机制.

目前人类对地球的认识仍很肤浅,无论国外还是国内对于地球动力学问题仍在探索过程中,Science杂志2005年公布的125个重大科学问题中的第10个问题是"地球内部是如何运行的",提出地球动力来源还尚未解决。2017年出版的《中国学科发展战略——板块构造与大陆动力学》认为板块构造理论虽然取得了巨大成功,但该学说依然存在其形成以来就存在的难题,即板块动力、板块起源及板块上陆三大问题,驱动板块运动的动力机制是最为重要的问题,也是亟待解决的问题。研讨会分两个环节,一是主要观点报告环节,二是讨论争鸣环节。在报告环节,涉及动力机制的主要有5位报告人,分别阐述了他们的主要观点。梁光河提出了新大陆漂移说,通过大量证据分析认为传统的海底扩张驱动大陆漂移的模式存在很多问题,很多地质和地球物理观测事实说明持续推动大陆漂移的动力不是海底的持续扩张,而是大陆板块后下方持续的岩浆上涌推动大陆板块向前漂移,那是一个自发的连锁反应。万天丰认为传统的海底扩张传送带模式很难解释大陆板块漂移速度远远大于地幔对流速度这个问题,提出了陨击说。陨石撞击诱发地幔底劈推动大陆板块运动这个新的驱动模式。唐春安提出了地球龟裂说,认为地球内部热能的积累与释放,使得地质历史上岩石圈地幔具有冷热交替的周期。毛小平分析认为,目前所提出的地球动力中,只有周向应力具有足够数量级的应力,可以推动板块运动;周向应力在岩石圈薄弱处释放从而产生地壳相对运动;长期以来解释不了的"地壳异常压力"其实就是周向应力,而可独立于重力的构造力、碰撞力并不存在。在讨论争鸣环节,大家针对地壳运动的动力来源自由发言。梁光河指出万天丰提出的陨石撞击可以较好地解释超大陆裂解的初始动力,但不同意陨石撞击可以提供持续的大陆漂移的动力,以印度板块的北漂为例,因为地幔的巨大黏滞阻力,需要无数个陨石定点撞击印度板块后面才可能持续推动印度板块漂移。唐春安提出地球的锅盖效应,因此上地幔具有冷热周期,在热周期地壳才会大规模漂移,按照力学机制,大洋中脊和转换断层不可能是海底扩张产生的,应该是大陆漂移拉开产生的断裂系统。最后杨巍然总结发言,认为陨石撞击是一个重要因素,地球上的构造运动都可以归结为开合运动,海底扩张和大陆漂移都是存在的,地体构造也是科学的。研讨会取得的共识是:大陆的确存在大规模水平运动,传统的地幔对流传送带驱动模式存在很多与观测事实不符的问题,需要重新认识驱动机制和驱动力的问题,对板块俯冲问题多数持怀疑甚至反对的观点。其驱动力应该来自重力和地球内部热力,但它们之间是如何相互作用的,仍需要进行更深入的研究。

Full waveform inversion (FWI) is a powerful tool for reconstructing high-resolution subsurface parameters estimated by iteratively minimising the difference between calculated and observed data. Step-length estimation is a key step in the successful implementation of the FWI algorithm. An optimal step-length value rapidly causes the FWI algorithm to reach the global minimum with reduced iterations and fewer extra forward modelling simulations during each iteration. Step-length can typically be calculated using an inexact or an exact line-search method. The backtracking line-search method (BLSM) is a typical inexact method. Initial methods of guessing the step-length and evaluation conditions determine the efficiency of a BLSM scheme. Here, we propose a quadratic extrapolation value as the initial guess in a BLSM scheme, and then compare it with other initial-guess approaches by using the first Wolfe condition to evaluate step-length values. Exact line-search methods include a parabolic fitting search method through three points (PFSM-3), a parabolic fitting search method through two points (PFSM-2) and the analytical step-length method (ASLM). To find optimal and stable step-length estimation methods for FWI, we compare four step-length estimation methods: BLSM, PFSM-3, PFSM-2 and ASLM. Numerical examples using synthetic data demonstrate that quadratic extrapolation values perform better than first-order change and adaptive values in the BLSM scheme, in terms of resolution of the reconstructed model and computational costs. Of the four step-length estimation methods, ASLM and BLSM are both efficient for noise-free data, and robust ASLM is more efficient for noisy data. However, PFSM-2 and PFSM-3 are less efficient because of low accuracy and high computational cost.

老挝万象盆地蕴藏有丰富钾盐矿,钾盐成矿后受到了后期构造运动的强烈改造.后期构造运动对万象盆地的钾盐矿产生了怎样的改变?一直缺乏深入研究.本次研究表明,在挤压走滑背景下,后期的构造运动对钾盐进行改造,并使得钾盐矿体发生了塑性柔流和脆性滑移.万象盆地萨塔尼钾盐矿区的三维地震勘探结果表明,无论水平切片还是垂直剖面上,都清晰地显示了构造运动对钾盐矿和地层的后期改造.钻探岩心也显示与构造运动有关的柔流变形.通过钻孔测井资料对三维地震勘探进行标定,可以准确外推钾盐矿体的横向变化并预测定位钾盐矿的空间位置.最终在老挝万象盆地萨塔尼一个很小的矿区详勘发现了一个超大型钾盐矿床,因此三维地震在万象盆地钾盐矿后期改造和勘探方面发挥显著作用.

地震的成因机制和大陆漂移的关系是地球科学持续研究的重要问题,首先通过对2008汶川地震的弹性应变能量计算,表明弹性应变能不足以产生8级地震的能量,然后结合新大陆漂移模型,说明大地震的主控因素主要是地下深处的高温高压地壳流和活动深断裂,地震和大陆漂移过程密切相关.地震形成过程也是一个隐爆过程.最后对全球地震和中国及亚洲地震进行解剖,同时对地光现象的产生机制进行了深入分析.

郯庐断裂是中国东部的一个巨型断裂,目前关于郯庐断裂的几个关键问题仍存在较大争议:一是郯庐断裂的长度;二是郯庐断裂的走滑距离和走滑深度;三是郯庐断裂的形成与活动时间;四是郯庐断裂与胶东金矿的关系.基于地质、地球物理和地球化学研究结果,结合近期郯庐断裂带区域高精度石油地震勘探资料和地质测年资料,通过大地构造演化史恢复说明,郯庐断裂的雏形出现在中生代的中央造山带东段,走滑开始于新生代初期,大规模平移走滑发生在45～24 Ma,并持续活动至今.郯庐断裂总体左行走滑量约为760 km,总长度约为3000 km.对于胶东金矿,郯庐断裂主要是一个改造断裂.郯庐断裂带的形成和演化与中新生代欧亚板块东缘的构造环境变化密切相关.研究结果为中国东部大地构造动力演化及成矿过程研究提供了新思路.