松辽盆地滨北地区区域构造特征及意义——地震长剖面给出的证据

松辽盆地位于西太平洋大陆边缘北部,其主体部分位于黑龙江板块群的中部。松辽盆地整个上部地壳所受到的挤压应力场在南北两大地区存在空间差别。在板块构造理论指导下,利用研究区内的地震长剖面资料,研究松辽盆地滨北地区区域构造特征。通过分析认为,滨北地区东、西部多为隆起或斜坡区,而中部多是凹陷,从南向北,地层沉积厚度逐渐变薄。早期的断层活动导致了凹陷内凹隆相间的构造特点。     

洋脊俯冲及其在新疆阿尔泰地区存在的可能证据

本文综述了洋脊俯冲的研究历史与现状,论述了与洋脊俯冲相关的各种构造运动、岩浆活动以及成矿特点。同时,系统总结了阿尔泰南缘已报道的可能与洋脊俯冲有关的证据,如埃达克岩和富铌玄武岩、玻安岩、苦橄岩、A型花岗岩、双峰式火山岩、阿拉斯加型杂岩、酸性岩墙群等特殊的岩石类型,以及可能与洋脊俯冲相关的变质变形作用,认为洋脊俯冲模式可以合理的解释阿尔泰南缘的这些岩石组合以及变质变形作用。此外,分析了晚古生代阿尔泰南缘洋脊俯冲的时空分布,阐述了洋脊俯冲对中亚造山带陆壳增生及成矿的意义。     

汇聚背景下的多幕裂陷作用及其迁移机制:以南海北部珠江口盆地为例

南海的形成演化受控于印-澳、欧亚以及太平洋板块的相互运动,为研究汇聚背景下板块碰撞及其远程效应提供重要窗口。为了揭示该汇聚背景下的多幕裂陷过程,本文选取地质信息丰富的整个珠江口盆地为典型区,利用三条高精度地震剖面,对盆地各地质单元进行断层活动速率和构造沉降速率的定量计算及综合分析。结果表明盆地裂陷期东部、中部和西部主要控凹断层的平均活动速率分别为96 m/Ma、223 m/Ma和124 m/Ma,且其平均沉降速率依次为8.5 m/Ma、34 m/Ma和12.7 m/Ma,盆地整体呈现中部裂陷作用最强,其后向西部和东部逐渐减弱的特征。本文认为这与先存断裂以及初始地壳厚度有关:盆地东部和中部存在NE向先存断裂,并且东部先存断裂更加活跃,因此在新生代拉伸应力下东部更易表现为裂陷作用最强的区域,其次为中部和西部;而受前新生代时期俯冲作用的影响,岩浆的底垫作用引起盆地东部地壳增厚,东部裂陷作用强度急剧降低,造成裂陷作用强度的东西差异。此外,盆地南段凹陷裂陷期的断层活动和沉降速率发生激增,裂陷作用存在向南迁移的现象。本文推测在深度相关的伸展模式的影响下,南段凹陷地壳温度升高,强度减弱,因而在伸展应力下发生快速的拉伸减薄,导致裂陷中心向南迁移及岩浆物质上涌。同时,侵入的岩浆物质导致高角度正断层转换成低角度正断层,进一步促进裂陷中心向南迁移。     

Three-dimensional P- and S-wave velocity structures beneath the Japan Islands obtained by high-density seismic stations by seismic tomography

We construct fine-scale 3D P- and S-wave velocity structures of the crust and upper mantle beneath the whole Japan Islands with a unified resolution, where the Pacific (PAC) and Philippine Sea (PHS) plates subduct beneath the Eurasian (EUR) plate. We can detect the low-velocity (low-V) oceanic crust of the PAC and PHS plates at their uppermost part beneath almost all the Japan Islands. The depth limit of the imaged oceanic crust varies with the regions. High-V_P/V_S zones are widely distributed in the lower crust especially beneath the volcanic front, and the high strain rate zones are located at the edge of the extremely high-V_P/V_S zone; however, V_P/V_S at the top of the mantle wedge is not so high. Beneath northern Japan, we can image the high-V subducting PAC plate using the tomographic method without any assumption of velocity discontinuities. We also imaged the heterogeneous structure in the PAC plate, such as the low-V zone considered as the old seamount or the highly seismic zone within the double seismic zone where the seismic fault ruptured by the earthquake connects the upper and lower layer of the double seismic zone. Beneath central Japan, thrust-type small repeating earthquakes occur at the boundary between the EUR and PHS plates and are located at the upper part of the low-V layer that is considered to be the oceanic crust of the PHS plate. In addition to the low-V oceanic crust, the subducting high-V PAC plate is clearly imaged to depths of approximately 250 km and the subducting high-V PHS zone to depths of approximately 180 km is considered to be the PHS plate. Beneath southwestern Japan, the iso-depth lines of the Moho discontinuity in the PHS plate derived by the receiver function method divide the upper low-V layer and lower high-V layer of our model at depths of 30–50 km. Beneath Kyushu, the steeply subducting PHS plate is clearly imaged to depths of approximately 250 km with high velocities. The high-V_P/V_S zone is considered as the lower crust of the EUR plate or the oceanic crust of the PHS plate at depths of 25–35 km and the partially serpentinized mantle wedge of the EUR plate at depths of 30–45 km beneath southwestern Japan. The deep low-frequency nonvolcanic tremors occur at all parts of the high-V_P/V_S zone—within the zone, the seaward side, and the landward side where the PHS plate encounters the mantle wedge of the EUR plate. We prove that we can objectively obtain the fine-scale 3D structure with simple constraints such as only 1D initial velocity model with no velocity discontinuity.     

陆内裂陷盆地构造动力学分析

陆内裂陷盆地区形成和演化过程中的构造力包括4方面：（1）地幔对流由岩石圈板块底面边界施加到岩石圈板块内部的构造力F1;（2）板块相对运动通过岩石圈板块侧面边界施加到岩石圈板块内部的构造力F2;（3）岩石圈受热膨胀和冷却收缩在地壳内部产生的构造力F3;（4）地壳质量在地壳内部产生的围压F4。地壳中的应力是这4方面的构造力的函数S(Fi),其中,F1和 F2的大小和方向对三轴应力状态的主应力大小和方向起决定作用。地壳发育正断层的条件是应力状态方程S（Fi）中σ2 σ3主应力平面大致处于水平面状态、σ1近直立。当F1和F2的方向一致且F1＞F2或F1和F2的作用方向相互垂直的情况下,F1和F2合成的应力场中的最小主应力方向与X轴方向一致,地壳发生正向裂陷作用。在F1和F2的方向既不平行也不垂直的情况下, F1和F2叠加产生最小主应力（σ3）的方向与X轴方向不一致,地壳发生斜向裂陷作用。当地幔对流从岩石圈底部对岩石圈产生的引张作用力减小、板块之间相对运动从岩石圈侧面边界对岩石圈产生的挤压作用力增强的情形下,地壳应力状态S（Fi）在X轴和Y轴构成的水平面上的最大主应力可能超过Z轴方向的主应力,使σZ相当于三轴应力状态的σ2,裂陷盆地发生走滑构造变形。如果地壳应力状态S（Fi）在X轴和Y轴构成的水平面上的最小主应力也超过Z轴方向的主应力,则σZ相当于三轴应力状态的σ3,裂陷盆地发生收缩构造变形,可能发育逆冲断层或使早期的正断层发生反转位移。随着裂陷作用的渐进发展,不同时期F1和F2的大小和方向的变化导致地壳应力场的主应力轴方向也相应发生变化,使裂陷盆地在不同演化阶段表现出不同的构造变形特征。     

The system of Cenozoic depressions in the Amur and Primorye regions: The structure, tectonic position, and geodynamic interpretation

The analysis and synthesis of the seismic data, the local gravity field, and the geological evidence reveal that the faults representing a framework for a system of the Cenozoic depressions in the Amur and Primorye regions define various structural parageneses: en echelon sets, extension duplexes, and conjugate knots. Being regularly arranged, they form a single branched-reticulate regional disjunctive zone named the Ussuri-Okhotsk rifting zone (UORZ). Owing to the relation with the faults of the Tan-Lu system and the graben-shaped basins of the marginal seas, this zone is an element of the pericontinental zigzag lineament zone, which controls the East Asian graben belt. The Ussuri-Okhotsk rifting zone represents a wide incipient right-lateral transtensional zone, which was formed under conditions of a pure shear deformation accompanied with additional extension. The compression and extension axes were oriented in the northeastern and northwestern directions, respectively. This deformation was responsible for passive dispersed epiorogenic and epiplatform rifting. After the episode of Late Miocene tectonic inversion, the rifting acquired taphrogenesis features. The tectonic movements were largely confined to extended deep-seated faults and led to the formation of spacious two-stage depressions. Simultaneously, the role of active rifting substantially increased, which is evident from the development of numerous Neogene-Quaternary basaltic plateaus. The rifting became more intense to form larger depressions reflecting deeper endogenic processes. This could probably be related to the mantle magmatism, the regional consolidation of the crust, changes in its structural anisotropy, and the insignificant reorganization of the tectonic stress field.     

Process of Rifting and Collision along Plate Margins of the Qinling Orogenic Belt and Its Geodynamics

The Qinling erogenic belt underwent complicated processes of rifting and collision, as shown by the coexistence of (1) ocean extension and plate margin rifting and (2) subduction of the frontal oceanic crust and extension of the rear plate margin. These resulted in a basin-mountain framework characterized by the coexistence of plates separated by the ocean basin and continental blocks demarcated by the rifting sea trough in the marginal region and the coexistence of subduction orogeny and ocean extension. Generally speaking, the plate marginal area between the North China plate and Yangtze plate continually rifted from north to south and the rifted micro-plates continually accreted northwards. This especial orogenic process was probably controlled by two events of deep mantle geody-namic adjustment and mantle plume activities, which occurred in the Shangdan suture belt and Mianlue suture belt from north to south respectively.     

Plate subduction,and generation of earthquakes and magmas in Japan as inferred from seismic observations: An overview

A dense nationwide seismic network recently constructed in Japan has been yielding large volumes of high-quality data that have made it possible to investigate the seismic structure in the Japanese subduction zone with unprecedented resolution. In this article, recent studies on the subduction of the Philippine Sea and Pacific plates beneath the Japanese Islands and the mechanism of earthquake and magma generation associated with plate subduction are reviewed. Seismic tomographic studies have shown that the Philippine Sea plate subducting beneath southwest Japan is continuous throughout the entire region, from Kanto to Kyushu, without disruption or splitting even beneath the Izu Peninsula as suggested in the past. The contact of the Philippine Sea plate with the Pacific plate subducting below has been found to cause anomalously deep interplate and intraslab earthquake activity in Kanto. Detailed waveform inversion studies have revealed that the asperity model is applicable to interplate earthquakes. Analyses of dense seismic and GPS network data have confirmed the existence of episodic slow slip accompanied in many instances by low-frequency tremors/earthquakes on the plate interface, which are inferred to play an important role in stress loading at asperities. High-resolution studies of the spatial variation of intraslab seismicity and the seismic velocity structure of the slab crust strongly support the dehydration embrittlement hypothesis for the generation of intraslab earthquakes. Seismic tomography studies have shown that water released by dehydration of the slab and secondary convection in the mantle wedge, mechanically induced by slab subduction, are responsible for magma generation in the Japanese islands. Water of slab origin is also inferred to be responsible for large anelastic local deformation of the arc crust leading to inland crustal earthquakes that return the arc crust to a state of spatially uniform deformation.     

Tectono-Sedimentary History of Southeastern Coast Region,China:a Synthesis

According to the ideas and concepts of systems dynamic of continent structure, using previous information related to the study area, combining analyses on orogenic belt, basin and magmatic rock, the present paper synthesizes the tectono-sedimentary development of southeastern coast region, China, with special emphasis on the mountain making, basining and magmafc activity. The tectonic evolution after Late Caledonian orogeny was dominated by alternating rifting and converging, subsiding and uplifting, mountain making and basining in central and southern parts of southeastern China and the adjacent regions to the east and west. Seventeen geologic events, nine events of plate or terrain convergence , and continental crust accretion, as well as eight events of intracontinental rifting and basin faulting , are closely related to the tectonic and sedimentary evolution of the study area. The accompanied intense and frequent sedimentation , folding , faulting , magmatism and ore-forming process allowed huge coal     

Seismic models of inner parts of the Euro-Asian continent and its margins

Analogies are drawn between continental and continental margin structures on the basis of seismic data on the crustal structure of Eurasia and its Atlantic margins. Crustal thinning from the inner parts of the continent to its margins is observed to be a general feature common to the formation of deep midland depressions and sedimentary basins of shelf zones. The latter are characterized by crustal thinning and its assimilation. These phenomena cannot be explained solely be sea-floor spreading effects in the process of active rifting and formation of oceanic crust. It appears that the main role in the formation of the margins in played by processes of mantle erosion in connection with heating at continental margins and with the migration of mantle material to the lower part of the crust.     

青藏高原重力构造

青藏高原的范围大致由昆仑山、阿尔金山、祁连山、龙门山及喜马拉雅山所围限。是一个边部群峰耸立、内部相对平坦的广阔高原,具有山高地势平的地貌景观。地壳厚度一般为50—70公里,成为全球地势最高、地壳最厚的地区。 中新世晚期,喜马拉雅尚未成山,其高度接近海面,仅约数百米。而由冈底斯山至昆仑山的广大地区,此时形成了统一的夷平面,具有与喜马拉雅地区相似的高度。     

塔中低凸起东端冲断构造与寒武系内幕白云岩油气勘探

塔里木南缘早古生代板块构造控制了塔南一塔中从伸展到挤压的演化.寒武纪-早奥陶世板缘拉张控制了塔中北斜坡断陷构造.中奥陶世北昆仑洋盆关闭后塔中前缘隆起.晚奥陶世-晚泥盆世塔中前陆冲断与走滑构造变形.晚奥陶世-泥盆纪塔南前陆冲断由东南向西北方向传播,形成塘北-塔中南-5号断裂等弧形断裂体系和塔中低凸起中西段与Ⅰ号断裂带小角...     

燕辽地区燕山期火成岩与造山模型

通过与安第斯、青藏北缘、大陆裂谷带火成岩的比较，阐述了燕辽地区燕山期火成岩具活动大陆边缘靠内陆一侧的构造属性。提出了三种可能的母岩浆（玄武质、粗面质与花岗质）以及它们的混合作用是制约以壳幔混合型为主、组成谱系宽的火成岩的主要机制。基于实验岩石学成果，论述了无负Ｅｕ异常的中酸性火成岩类（正长岩、二长岩、石英闪长岩类）形成于加厚陆壳底部（或山根带）。主要基于岩石学成果，讨论了燕山期本区陆壳厚约６０～７０ｋｍ，岩石圈厚约１００～１５０ｋｍ。通过与印支期岩石圈（厚约１５０～２００ｋｍ）的对比，提出了造山岩石圈的拆沉－去根作用，使岩石圈减薄了约５０ｋｍ。由此，提出了一个大洋俯冲与岩石圈拆沉相结合的造山模型，称为华北式（或燕辽式）造山带模型。这一模型不但可以满意地解释为什么弧火成岩属性的岩浆活动可深入远离海沟达一千多公里的内陆地区以及挤压与拉伸交替的反转构造的发育，而且还可以比较满意地解释为什么火成岩组成极性极不明显，伴随岩浆活动的陆壳不断抬升等，并指出燕山期地幔岩石圈减薄，山根仍存在，所以造山后Ａ型花岗岩（指碱性正长岩类）仍保持无负Ｅｕ异常，而本区新生代处于大陆裂谷发育环境，地幔岩石圈与陆壳均减薄。     

Alternating episodes of extension and contraction during the Triassic: evidence from Mesozoic sedimentary basins in eastern Australia

Triassic to Lower Cretaceous continental sedimentary basins occur in eastern Australia, but the tectonic and structural evolution of these basins is not fully understood. Using gridded aeromagnetic data, seismic reflection data and field observations, we conducted a structural analysis aimed at characterising major faults and deformation style in these sedimentary basins. Our results show evidence for two alternating episodes of rifting during the Triassic. An earlier episode of rifting, which took place in the Early Triassic to early Late Triassic, is inferred based on synsedimentary normal faults in the Nymboida Coal Measures and the boundary West Ipswich Fault System in the Esk Trough. This phase of rifting was followed by a contractional event that resulted in tilting, folding, and thrust faulting. Evidence of synsedimentary normal faults and bimodal volcanism indicates that another rifting phase occurred during the Late Triassic and resulted in the development of the Ipswich Basin. From the latest Late Triassic to the Early Cretaceous, the accumulation of continental sediments in the Clarence-Moreton Basin was accompanied by subsidence. We suggest that the alternating rifting episodes and contraction were ultimately controlled by plate boundary migration and switches between trench retreat and advance during the Triassic.     

Analysis of explosions and seismic phenomena based on electromagnetic cracking of piezoelectric and piezomagnetic plates

Electromagnetic emission caused by fracturing of piezoelectric and piezomagnetic crystals in plates and its application for remote sensing of explosions and natural seismic and volcanic phenomena were studied theoretically. The difference of emission from piezoelectric and piezomagnetic plates in cases of explosions versus seismic and volcanic phenomena enables use of this analysis method for phenomenon identification. The analysis herein is based on a model of a plate of finite size with a uniformly moving crack. It has been demonstrated that time-dependent mechanical stresses, which exist in the vicinity of the crack apex, are sources of an alternating electromagnetic field. The nonstationary mechanical stresses in the vicinity of the moving crack cause nonstationary polarization currents, which include both potential and vortical components in the case of a piezoelectric crystal but only the vortical component in the case of a piezomagnetic crystal. In both cases, it is possible to observe the nonstationary magnetic dipole which is the source of the excited magnetic field in the near zone. Such a dipole is created due to the motion of the crack apex and depends on the specific crystalline symmetry. Comparison of the two types of crystal (piezoelectric and piezomagnetic) shows that emission from the piezomagnetic crystal is more effective. A very important result is that it is possible to observe the difference between seismic and volcanic versus industrial phenomena through analysis of the unloading wave, which is absent in the case of industrial phenomena. This opens the possibility to identify the type of disaster and take the correct decision.     

Mantle plumes and plate motions

This paper elaborates the hypothesis that convection plumes may be rising from the lower mantle to spread out in the asthenosphere and drive lithospheric plates about and thus possibly provide the primary mechanism which governs the behaviour of the earth's surface. The paper notes some characteristics of plumes and identifies more than thirty by the hot spots which overlie them. Most lie close to mid-ocean ridges and have produced aseismic ridges trending away from them on either plate. A few have been overridden by plates to produce single, isolated chains of seamounts and islands. One plume may have uplifted the Colorado Plateau. Such distinctions serve to identify five types of hot spots.Most plates are in motion over the lower mantle. They are considered to be driven by the plumes, but their paths are influenced by interactions with other plates. Some temporarily become more or less stationary relative to the lower mantle. It is held that stationary plates, of which Africa and Southeast Asia may be present examples, develop special characteristics among which much volcanism, epeirogenic uplift, rifting and the development of basins and swells are diagnostic.It is well-known that if two plates approach one another at a subduction zone that a continental plate generally overrides an oceanic one. It is here suggested that the question of which plate is more nearly stationary over the mantle is important and determines the character of the continental margin. It is held that, if a continental plate advances over an oceanic one which is fixed over the mantle, a migrating marginal trench and mountains of Andean type with huge batholiths will form on the leading edge of the continent. On the other hand, if a continental plate is fixed and one or more oceanic plates are advancing and sliding under it, island arcs (and, when a collision with another continent occurs, mountains of Appalachian type) will form along each coast towards which a plate is advancing.     

地体的单向和多向聚合与离散

地体构造是对板块构造理论的发展和补充,它受控于全球板块动力学体系,因此不能将地体与板块割裂开来去研究。其相对于刚性板块的小规模、多样性和广泛性,对了解全球板块的离散和大陆的拼贴增生过程具有十分重要意义。地体构造无处不在,它不仅存在于中、新生代陆缘造山带中,也存在于古老造山带中,一些古老的克拉通实际上也是由不同的地体拼合而成的。地体的运动包括聚合、离散和走滑三种方式,地体的增生作用是聚合的主要表现形式,并导致大陆的生长扩大,而地体的离散作用联合增生作用,决定了现代大陆的轮廓。分析地体聚合和离散的过程,可以发现有两种不同的模式,即单向聚合-离散和多向聚合-离散,它们对应了不同的地球动力学过程。地体的单向聚合-离散可以由大洋的俯冲增生或大陆汇聚碰撞而导致,但在这个过程中,大洋向大陆的单向俯冲起到了主导作用。地体的多向离散和聚合与岩石圈的裂解与汇聚有密切联系,从全球构造演化的格局来看,岩石圈裂解与汇聚的方向本身具有多向性,这就导致了一些微陆块地体与具洋壳性质的地体一同发生多向离散和聚合。地体的单向离散和聚合会因构造变动而转变为多向离散和聚合,俯冲板片回转与海沟后撤会导致俯冲带弯曲和俯冲方向的改...     

Transtensional folding

Strain modeling shows that folds can form in transtension, particularly in simple shear-dominated transtension. Folds that develop in transtension do not rotate toward the shear zone boundary, as they do in transpression; instead they rotate toward the divergence vector, a useful feature for determining past relative plate motions. Transtension folds can only accumulate a fixed amount of horizontal shortening and tightness that are prescribed by the angle of oblique divergence, regardless of finite strain. Hinge-parallel stretching of transtensional folds always exceeds hinge-perpendicular shortening, causing constrictional fabrics and hinge-parallel boudinage to develop.These theoretical results are applied to structures that developed during oblique continental rifting in the upper crust (seismic/brittle) and the ductile crust. Examples include (1) oblique opening of the Gulf of California, where folds and normal faults developed simultaneously in syn-divergence basins; (2) incipient continental break-up in the Eastern California-Walker Lane shear zone, where earthquake focal mechanisms reflect bulk constrictional strain; and (3) exhumation of the ultrahigh-pressure terrain in SW Norway in which transtensional folds and large magnitude stretching developed in the footwall of detachment shear zones, consistent with constrictional strain. More generally, folds may be misinterpreted as indicating convergence when they can form readily in oblique divergence.     

南海海底地震仪三维深地震探测的进展及挑战

获取深部速度结构是认识南海形成演化模式的基础.海底地震仪（OBS）二维与三维深地震探测技术是获取深部速度结构最成功的方法之一.OBS三维探测结果揭示:西南次海盆横跨残留扩张脊两侧洋壳不对称增生的速度结构特征;东部次海盆具有4种不同洋壳类型的速度结构;珍贝-黄岩海山链是在海盆停止扩张后6~10 Ma岩浆活动形成的;东沙隆起区显示了张裂期后的岩浆活动及其上涌通道;南海东北部马尼拉俯冲带前缘是受到张裂期后岩浆活动影响的减薄陆壳.IODP367-368钻探区实施的OBS三维探测将以建立南海洋陆转换带（COT）张裂-破裂机制模型为科学目标.OBS三维探测方法在南海各向异性、岩浆活动、形成演化等方面将继续发挥着不可替代的作用.      

The deep structure of the central Alps inferred from both geophysical and geological data

Gravity surveys of the past century established that mountains have roots, seismic refraction lines shot in the second half of this century confirmed the downbulge of the Moho under the Alps, and recent reflection traverses provided new details on the behaviour of crustal layers in the deep part of the Alps. However, geophysical data are ambiguous geologically. For models of the root in terms of rock distribution to be tectonophysically acceptable, they must be the retrodeformable result of kinematic sequence that fits the geological surface data. For a cross-section through the Swiss Alps based on refraction data and somewhat modified by the recent reflection traverses, a kinematic model compatible with large-scale geological data may be obtained by the superposition of three Neogene phases with alternating vergence. Although Alpine collision is largely dextrally compressive in the central Alps, the N-S component may be discussed in a cross-section. Particularly puzzling geophysical features include a high-velocity body in the middle crust and the disappearance of the layered foreland crust in the root. In order to account for these phenomena, it is proposed that the crustal root is interpreted as the result of complex reshuffling of middle and lower crustal masses as well as large-scale phase transformations. The mid-crustal highvelocity body is interpreted as a delaminated section of the lower crust of the Adria plate that was wedged into the middle crust of the Alps in the middle Miocene. The disappearance of the foreland lower crust is attributed to eclogitization attendant on the subduction of continental crust. Material balance estimates suggest that during Alpine collision large volumes of continental crust have disappeared through subduction.