蛇绿岩是恢复大洋演化最直接的证据,是识别板块汇聚边界的一级地质学标志.相比于蛇绿岩,蛇绿混杂岩的基质记录了更多关于大洋板块演化的信息.为了深入理解蛇绿混杂岩基质组成的构造内涵,我们选择了位于越南北部—中国滇东南地区的古特提斯哀牢山-Song Ma(马江)-Song Chay(斋江)缝合带开展研究.本文综合了前人有关该带蛇绿混杂岩基质碎屑锆石U-Pb定年和Hf同位素分析的结果,认为哀牢山-Song Ma-Song Chay蛇绿混杂岩基质具有强烈的横向不均一性,可以划分为M1、M2、M3和Song Chay单元.其中,M1位于哀牢山-Song Ma蛇绿混杂岩中部,构成了哀牢山蛇绿混杂岩的主体,具有440 Ma和960 Ma的特征碎屑锆石年龄峰值,结合其Hf同位素特征,我们认为M1的物源为印支板块.M2位于哀牢山-Song Ma蛇绿混杂岩的NW部,显示出单一的260 Ma左右的碎屑锆石年龄峰值,结合其Hf同位素特征,我们认为M2主要来自于华南板块上的峨眉山大火成岩省.M3位于哀牢山-Song Ma蛇绿混杂岩的SE部,碎屑锆石年龄结果显示出250 Ma的主要峰值以及370 Ma和780 Ma的次要峰值,结合其Hf同位素特征,我们认为M3的主要物源为印支板块的弧岩浆岩,少量来自华南板块.Song Chay蛇绿混杂岩基质中的碎屑锆石主要是来自作为被动陆缘的华南板块,只有很少一部分来自上覆的印支板块.上述蛇绿混杂岩组成的横向不均一性,指示了洋盆关闭过程中物源的变化.更重要的是,基质中鲜明的俯冲板块(华南)被动陆缘的信息,使我们推断古特提斯东部在某一阶段或某一部位表现为有限洋盆,其对我们理解东古特提斯板块拼合过程具有重要意义.

中生代以来, 华北克拉通岩石圈发生大规模减薄, 岩石圈地幔的物理、化学性质发生显著改变, 这一过程通常被称为华北克拉通破坏. 目前在华北克拉通东部大规模发育的岩浆岩是岩石圈深部减薄过程在浅部的重要响应, 也是克拉通破坏在浅部的直接表现. 岩体侵位机制和侵位过程与大地构造背景密切相关, 并记录同期区域大地构造信息. 15年来, 通过对华北克拉通东部不同岩浆发育阶段(晚三叠世、早侏罗世、晚侏罗世、早白垩世早期及早白垩世晚期) 22个花岗岩体开展磁化率各向异性(AMS)的研究, 反演岩体的就位过程; 结合早白垩世早期广泛发育的变质核杂岩, 探讨岩体侵位的构造背景, 进一步约束华北克拉通在不同阶段的构造背景及其与克拉通破坏的相关性. 其中, 晚三叠世、早侏罗世和晚侏罗世岩体均具有一致的N(E)-S(W)向的磁线理, 早白垩世早期岩体和变质核杂岩以NW-SE向(磁)线理为主, 早白垩世晚期岩体的磁线理则比较分散. 结合区域构造, 我们推断晚三叠世、早侏罗世和晚侏罗世岩体侵位受区域N(E)-S(W)向弱伸展构造体系的控制, 早白垩世早期岩体侵位则受区域NW-SE向伸展构造体系的控制, 而早白垩世晚期岩体就位与先期浅表弱伸展已经产生空间相关. 总而言之, 华北克拉通中生代伸展构造经历了从N(E)-S(W)向NW-SE的转变, 并体现出阶段性由弱渐强的表现. 上述伸展构造发育方向的转变可能代表蒙古-鄂霍茨克带和古太平洋板块与欧亚大陆东部相互作用过程.

Changbaishan/Paektu volcano straddles the border between the Democratic People's Republic of Korea and China. It was responsible for one of the largest eruptions in history, the "Millennium Eruption' of 946 CE. An episode of unrest between 2002 and 2005, characterized by inflation and seismicity, refocused attention on this volcano. While satellite remote sensing has provided synoptic observations, ground-based surveillance has hitherto supported only disparate analyses and geophysical interpretations on either side of the border. Here, we derive receiver functions using seismic records from both Democratic People's Republic of Korea and China. H-kappa stacking indicates thick crust (up to 40 km) and high average crustal V-P/V-S (up to 1.93) beneath the volcano. Grid search inversions constrain a significant velocity reduction at 4-8 km depth (below sea level), and harmonic analysis suggests this dips away from the volcano, with shallowest depths centered beneath the volcano. Common conversion point migrations show that this anomaly extends similar to 30 km from the volcano summit and possibly as far as neighboring volcanoes. The colocation of the velocity reduction with a zone of high-conductivity, low-velocity, and low-density material at the depth of the inflation source implicated in the 2002-2005 unrest indicates that partial melt is present directly beneath Changbaishan/Paektu, likely recharged during the episode of unrest. Our study highlights the importance of continued surveillance of the volcano and the need for further geophysical studies to constrain more fully the triggers for unrest and controls on its evolution.

The late Mesozoic tectonics of the North China Craton (NCC) and its adjacent regions were characterized by a general lithospheric extension and remarked by extensional dome structures, such as the metamorphic core complexes, syn-tectonic plutons, rolling-hinge structures, and widespreadgraben/half graben basins. According to our own field observations, laboratory work, and previous results of other groups, from north to south, five extensional domains have been delineated, namely Transbaikalia-Mongol-Okhotsk, western part of NCC, eastern part of NCC and Korea, Qinling-Dabie and its neighbouring, and the interior of South China Block, respectively. As the largest crustal scale extensional tectonic realm in the world, these domains are featured by a NW-SE extensional direction with strong extensional exhumation of middle to lower crust rocks to the surface along detachment faults. Geochronological work on these ductile detachment faults constrain a narrow activity period around 130 Ma except several extensive structures along the Tan-Lu fault, which documents a relative longer extensional period. The foundering of the lower part of the lithosphere could be a possible mechanism of this continent-scale extensional tectonics. This geodynamic model could help us to enhance the knowledge of the time, scale, and mechanism of the NCC destruction from the view of structural analysis.

The Indosinian orogeny plays an important role in the tectonic evolution of the South China block (SCB). As the biggest basin associated with the Indosinian orogeny on the southern margin of the SCB, the Nanpanjiang basin draws great attention in the geological community. Although many advances have been achieved, the time of the tectonic regime transition from extension to compression of the Nanpanjiang basin remains in dispute. In the central Nanpanjiang basin, the Paleozoic and Triassic strata are well outcropped around the Xilin faulted block, which provides an ideal studying object on revealing the basin evolution. In order to reveal the tectonic evolution of the Nanpanjiang basin, we have conducted a detailed sedimentary faces analysis, paleo-current measurement and frame-work clast statistics in the south flank of the Xilin faulted block. Our detailed field investigations show that the Lower Triassic on the south flank of the Xilin faulted block is composed of three subsequences which outcrop one by one in a southward younger order: (1) Tidal flat and lagoon deposits consist of mudstone, marlstone and calcarenite with tuff layers; (2) Mass-transport deposits (MTD) alternated with turbidite fan deposits include conglomerate, pebbly sandstone, fine sandstone and siltstone; and (3) Turbidite fans deposits include medium-coarse sandstone, siltstone and mudstone. The Middle Triassic consists of a sequence of coarse sandstone, fine sandstone, siltstone and mudstone which is interpreted to be a turbidite deposition. The facies' evolution indicates a deepening sediment environment during the Early to Middle Triassic. The paleocurrent and detrital composition analysis indicate that the detritus of the Lower Triassic in the Xilin area were mainly sourced from the Xilin fault block, while the Middle Triassic deposits in the basin were from composed provenances including the Jiangnan orogenic belt, the Kangdian massif, the Yunkai massif, the Emeishan basalt and the faulted blocks. The sediment facies' and provenance evolutions varying with time documented a sedimentary environmental evolution of the Nanpanjiang basin from the isolated carbonate platform to the half-deep sea turbidite basin. The Early Triassic MTD is the direct sedimentary records of the basin opening. The geological facts acquired in this study suggest that the Nanpanjiang basin was controlled by a regional extension regime in the Early Triassic, and the isolated carbonate platform with the Paleozoic strata is faulted blocks formed during the basin opening. In accord with this study, the mafic dikes (ca. 258 similar to 248 Ma) inside the basin intruding into underlying strata of the Lower Triassic and tuff interlayers (ca. 249.4 +/- 1.2Ma) in the Lower Triassic in the Xilin area also suggest an extension regime coeval with the basin opening during the Late Permian and the Early Triassic. The Middle Triassic turbidite fans are dominant deposits in the Nanpanjiang basin, which indicates the basin extension continued to the Middle Triassic. The opening of the Nanpanjiang basin is highly coincident with the closure of a branch of the Paleotethys Ocean in temporal and spatial, indicating that the basin was the part of subduction system of the Paleoethys oceanic lithosphere during the Late Permian to Middle Triassic. The absence of the Upper Triassic in the Napanjiang basin and adjacent areas indicates that the basin extension or subduction of the Paleotethys oceanic lithosphere terminated after the Middle Triassic.

The mafic intrusive rocks in the Funing area, Southeast Yunnan Province (Southwest China), are dominated by diabase with a small amount of gabbro-diabase. Previous workings interpreted them as part of the Emeishan Large Igneous Province, based on geochemical, isotopic and zircon U-Pb analyses. Geological surveys (the Guichao and Dongbo Sheets at a scale of 1 : 50000) in the Funning area conducted by this study show that diabase sheets or dikes not only intrude into Paleozoic strata, but also penetrate arc related basaltic andesites (ca. 255 similar to 241Ma) and low-middle Triassic strata (the Luolou Formation and Beifeng Formation, respectively). These geological facts clearly indicate that the emplacement of the mafic intrusive rocks in the Funing area was occurred after the Middle Triassic and significantly later than the Emeishan plume (ca. 263 similar to 252Ma). In addition, these mafic rocks are also significantly distinct from the Emeishan Large Igneous Province in the rock types and assemblages. Therefore, the geological facts presented in this study come to a conclusion that the mafic intrusive rocks in the Funing area are the product of magmatism after collision orogeny between the South China and Indochina blocks (Indosinian orogeny), rather than the part of the Emeishan Large Igneous Province.

Eastern China was dominated by compressional structures in early Mesozoic but vast extensional structures in the Late Mesozoic.A large number of extensional structures,such as metamorphic core complexes,syntectonic plutons,detachments and domes,have exhumed the middle to lower crust into surface,and changed the structure of middle-lower crust dramatically.This paper aims to investigate the late Mesozoic structures in typical areas of Eastern China that include Yanshan tectonic belt in the north,Dabie-Sulu tectonic belt in the central and the coastal tectonic belt in the southeast.This project will also try to reconstruct the tectonic framework before Yanshanian period for its critical role to know how crust deformation responded to interaction and deep process of plates during the Yanshanian period.The purpose of this project is to illuminate the tectonic phase,activity time,dynamic mechanism,and relationship to relevant plates in Eastern China during Yanshanian period,and discuss the constraint on the metallic mineralization.

The characteristics of the Laoshan' ao shear zone and its relationship with the Xiangdong tungsten deposit are long-standing controversial issues. The disputes exist as follows: (1) whether the Laoshan' ao shear zone is a thrust fault, a normal fault or a strike-slip fault and what is its development mechanism; (2) what is the relationship between the Laoshan' ao shear zone and the mineralization of the Xiangdong tungsten deposit, it is promoting or damaging? In order to answer these two questions, systematical macro and micro-structures analyses were conducted along the Laoshan' ao shear zone and the Xiangdong tungsten deposit in this study. Two stage events are defined on the base of these structural observations: the first extensional detachment with a top-to-the-SE shearing coeval with the emplacement of the Batuan granitic pluton during the Late Jurassic, forming the extensive and pervasive brittle and ductile deformation. In the shear zone, the development of a serials of R and R' joints, which are facilitated by the activities of high-pressure fluid, provide the accommodation for the quartz vein type tungsten deposit; and then in the Late Cretaceous or later, the Laoshan' ao shear zone is featured by the NW-thrusting motion, resulting in exhumation of the hanging wall with its the ore veins to the shallow depth. We suggest that the emplacement of the Batuan pluton in the Late Jurassic and the development of the Laoshan' ao shear zone jointly facilitated the formation of the Xiangdong tungsten deposit. This study provide us a vivid example of structure controlled ore forming process in which the high-pressure fluid caused increasing local strain and reducing rock strength lead to the development of serials of brittle fractures (e. g. T joint, R and R' joints) in the shear zone, there factures finally provides the accomodation for the ore-fluid precipitation and mineralization.

To understand the genesis of the 25 March 2007 Noto-Hanto earthquake (Mw 6.6), we determined high-resolution 3-D seismic velocity (Vp and Vs) and Poisson's ratio (σ) images in the epicenter area using 24,698 P-wave and 22,927 S-wave arrival times from 809 earthquakes and 265 sP depth-phase data collected from seismograms of 162 earthquakes beneath the Japan Sea. The sub-oceanic events are relocated accurately by using P-, S- and sP depth-phase arrival time data jointly. Our results demonstrate that the seismic velocity (Vp and Vs) and Poisson's ratio (σ) vary markedly in the source area. In and around the main shock hypocenter, low-velocity and high-σ anomalies are revealed, which are apt for accumulation of differential strain to bring the brittle failure. We infer that the zone with pronounced low-velocity and high Poisson's ratio beneath the source area reflects fluid-related anomalies derived either from the dehydration of the subducting Pacific slab or from permeation of sea-water through deep-seated active faults or both to the main shock hypocenter, which in turn may have facilitated the rupture initiation of the main shock and its aftershock sequence by weakening the overlying seismogenic layer beneath the region. Our study reinforces the concept of fluid-driven earthquakes in the peninsular regions, elsewhere in the world.

利用日本气象厅（JMA）以及日本国立大学联合地震观测台网（JUNEC）记录到的3218个地震事件的231918条P波到时资料,反演求得西南日本160km深度范围内的三维P波速度结构。研究表明,在九州地区,俯冲的菲律宾海板块以高速为主要特征,该海洋板块在30～60km深度处的脱水使得弧前地幔楔顶端的橄榄石蛇纹岩化,在120km深度处的脱水使得地幔楔中的岩石局部熔融,融体上升引起该区的火山活动。在本州西部地区大山火山之下,低速异常显著,并伴随低频地震活动,说明该火山可能是个潜在的活火山,将来有喷发的可能性。