宁夏贺家口子地区晚新生代地层序列及其构造意义

对宁夏贺家口子新生代剖面进行了详细的岩石地层和磁性地层研究，并重点标定了晚第三纪和早第四纪地层的年代。结合相应的地层接触关系和沉积相研究，获得了该剖面构造事件序列信息。认为：青藏高原东北边缘的海原－同心弧形构造束地区强烈的新生代构造变形开始于10MaBP左右，并经历了多个变形阶段。贺家口子剖面所揭示出来的这种构造变形特征，在青藏高原东北边缘地区具有区域意义。     

中、上扬子白垩纪以来的剥蚀过程及构造意义——低温年代学数据约束

通过对磷灰石裂变径迹（AFT）数据系统的对比,本文从整体上分析了中、上扬子区块各地质单元在晚中生代、新生带抬升冷却特征,并初步构建了区域上中-新生代构造活动与内陆变形的时空关系.它们的构造活动在空间上具有分区性和连续性特征,在时间上具有幕式性特征.空间上的分区性与连续性主要表现在各地质单元隆升特征的差异性,即中扬子北缘江汉盆地、黄陵隆起最早开始冷却到大巴山逆冲带、米仓山-汉南隆起晚侏罗世自北（东）向南（西）的隆升与江南-雪峰山隆起、湘鄂西褶皱带、川东褶皱带及川东北地区自南东向北西依次递进逆冲褶皱变形的差异;构造活动时间上的幕式特征主要表现在阶段性的快速冷却及其相间的缓慢冷却过程.中、上扬子北缘大巴山逆冲带、米仓山-汉南隆起磷灰石裂变径迹年龄从北（东）向南（西）逐渐变小,它们在晚中生代、新生代处于秦岭-大别造山带向扬子地块逆冲挤压变形的动力学背景;而湘鄂西褶皱带、川东褶皱带及川东北地区磷灰石裂变径迹年龄自南东向北西方向减小的趋势主要受控于太平洋板块的俯冲挤压效应.中、上扬子喜山晚期的快速冷却主要是青藏高原隆升及其向东与南东方向构造逃逸挤压作用及亚洲季风等气候变化的响应.磷灰石裂变径迹的系统分析为中、上扬子递进扩展构造变形提供了年代学约束.     

The chronology of intermontane-basin development in the northwestern Himalaya and the evolution of the Northwest Syntaxis

The Northwest Syntaxis delineates a complex zone where the northwesterly trending Himalayan Ranges meet the northeasterly trending Hindu Kush and Indus Kohistan Ranges. The southern margin of the Hindu Kush-Himalayan collisional belt is delineated by a series of imbricate thrusts that transect the northern edge of the modern Indo-Gangetic foredeep. The Kashmir and Peshawar Basins are embedded in this still-developing thrust belt and are symmetrically oriented about the Northwest Syntaxis.Consideration of chronologic, stratigraphic, structural, and geophysical data from the syntaxial zone permits the construction of a model for intermontane-basin development and the evolution of the Northwest Syntaxis during the Late Cenozoic. The formation of the Kashmir and Peshawar Basins results from the transfer from the north of the locus of thrusting and uplift to the southern margins of the basins. During the Pliocene, the morphotectonic emergence of the ancestral Pir Panjal and Attock Ranges along the southern margins of the two basins coincides with changes in the patterns of sedimentation and deformation both within the basins and in the bounding foredeep to the south. Contrasting styles of tectonic deformation on opposite sides of the Syntaxis are interpreted as a response to differences in the strength of sediment-basement coupling across the Syntaxis.     

龙门山南段芦山震区浅层沉积与构造变形——对深部发震构造的约束

2013年4月20日在龙门山南段发生M_W6.7强震,造成重大人员伤亡和财产损失.芦山地震发生后,针对发震断层是高角度还是低角度断层?断层的归属、性质和地震构造模型等问题,一直存在不同的认识和争议.本次研究采用了芦山震区的三条高精度二维人工地震反射剖面,结合区域地质、钻井资料,对芦山震区浅层沉积与构造变形进行综合解释;研究同时综合了震源机制解、小震重定位结果以及深地震探测剖面,并结合龙门山地区古生代以来的构造演化史,对震区地质构造进行解析.研究认为龙门山南段主要发育了三套不同层次的滑脱层并控制了上地壳形变,呈现多层滑脱、多期变形、构造叠加的复杂特征.2013年芦山地震的主要活动断层发育在深部约20 km滑脱层之上,倾向NW、倾角较陡大约在45°~50°,并产生反冲断层形成Y字状结构.地震地质解释表明,芦山地震的同震活动断层没有突破中生界和新生界,并非先前认为的双石—大川断裂(F4)或山前大邑隐伏断裂(F6);芦山地震的发震断层为一基底盲冲断层;深地震反射结果进一步揭示芦山地震的发震断层为一早期(古生代)形成的正断层.研究认为芦山地震发震构造符合简单剪切断层转折褶皱模型(Simple-shear Fault-Bend Fold),2013年芦山地震为一次非特征型地震.晚新生代以来在青藏高原向四川盆地强烈挤压持续作用下,早期正断层重新活动并产生了芦山地震.这种深部隐伏断层活化产生的特殊型地震,无疑增加了龙门山地区地震灾害的风险和不确定性.     

Cenozoic Tectonic Deformation and Related Geodynamics in the Western Part of Sichuan and Yunnan,Southwest China

Tectonic deformation of Cenozoic strata,youthful tectonontorphology,and high seismicity in the western part of Sichuan and Yunnan(Southwest China)marked intensive tectonism there during the Ceno7oic.It is a good place for studying the continental geodynamics because it is far away from those active plate boundaries surrounding the East Asian continent but near the southeastern margin of the Qinghai-Xizang(Tibet)plateau.The present study discriminated two phases of tectonic deformation with quite different styles in Cenozoic.Early compression deformation,expressed by folds,thrust,and even nappe structure,mainly occurred between the middle and late Eocene.Late extension deformation expressed by block-faulting started at least in the late Pliocene.Nonconformity,absence of strata,nonsuccessive tectonism,and inverse movement of the faults in late stages illustrated that two different deformation phases should be caused by different geodynamic processes.The early compression deformation would be related to Ar     

青藏高原东缘新生代早期古应力环境:来自四川盆地西南缘磁组构的记录

四川盆地西南缘紧邻龙门山褶皱冲断带(青藏高原东边界)南段.该地区的新生代早期红层沉积记录了青藏高原东缘的隆升历史及构造演变.本研究选取四川盆地西南缘芦山地区古新统—下渐新统名山组—芦山组地层剖面为研究对象,利用磁组构方法,结合前人对研究区古地磁及构造变形的研究,恢复了该地区新生代早期的古应力方向.本研究获取了548块样品的磁组构数据,这些磁组构的磁面理与层面平行,产状校正后磁线理呈NE-SW方向(39°/219°),K₃主轴方向相对集中(为120.9°±1.3°),为弱应变背景下平行层缩短之前初始变形磁组构类型,主要形成于地层成岩阶段,未受到后期褶皱等构造变形的强烈改造.本研究认为芦山剖面磁组构结果记录了研究区新生代早期的构造变形信息:新生代早期龙门山褶皱冲断带南段及川西南盆地受NW-SE向的最大主应力控制.该地区新生代晚期及现今应力场与新生代早期一致,可能继承了新生代早期的应力体制,暗示龙门山作为青藏高原的东边界可能在新生代早期已经形成.     

Insight into craton evolution: Constraints from shear wave splitting in the North China Craton

The multi-episodic tectonic activities from the Precambrian to Cenozoic, including nucleus formation, cratonic amalgamation, and rejuvenation, make the North China Craton (NCC) an ideal natural laboratory for studying craton evolution. Spatial change in the upper deformation records is an important aspect for understanding cratonic formation and rejuvenation. In this study, we performed seismic shear wave splitting analysis using SKS phases from 50 portable stations. Two different methodologies, shear wave splitting measurement and amplitude analysis of transverse/radial components, produced mutually consistent splitting results. These results showed that the seismic anisotropy beneath the Ordos Block can be divided into three subgroups reflecting the tectonic control. Combining these results with those from previous splitting studies in the eastern NCC, we suggest that the Proterozoic amalgamation generated the seismic anisotropy in the boundary zone between the Ordos Block and the Trans-North China Orogen, while the anisotropy in the eastern Trans-North China Orogen and eastern NCC were possibly associated with the lithospheric rejuvenation during the Late Mesozoic to Cenozoic.     

苏鲁皖地区晚新生代构造应力场的初步探讨

据考察区的晚新生代断裂活动性质和结合地震断层、地震应变带、震源机制、地形变、地壳测深等资料的综合分析,认为本区与华北北部的晚新生代应力场既有一致性,又有本身特点。推论是近邻诸板块相向挤压作用和伴随的深部物质运动而导致地壳上部侧向运动等不同级次作用力复杂叠加的结果。指出它与中生代区域应力场不同     

Northwest trending tectonic belt in the middle Yanshan Orogenic Belt of northeast Hebei Province,North China: Tectonic evolution and geochronology

1 An out-of-line northwest trending tectonic beltin the middle part of the Yanshan Orogenic Belt The tectonic framework of the intraplate YanshanOrogenic Belt is dominated by east-west and northeastextending structures as revealed by many geologists.There lies, however, a 100-km-long enigmatic out-of-line northwest extending tectonic complex in the mid-dle part of the Yanshan Orogenic Belt (fig. 1). Theresearch on the geometry, kinematics, timing of thiscomplex tectonic belt and its r…     

由地震活动参数分析安徽省新生代构造变形带现今活动习性与地震危险性

应用多个地震活动参数来判定断裂带分段落活动习性的方法,分析安徽省新生代构造变形带不同分段落的现今活动习性及地震危险性。研究结果表明：安徽省新生代构造变形带中存在着9个具有不同现今活动习性的分段落,其中,霍邱-风台、铜陵-宁国、明光-肥东3个段落现今活动习性处于较高应力背景下的相对闭锁状态．应属于有一定应变积累的潜在中强震危险段落：其它6个段落．现今活动习性处于中等或偏低应力背景下,以频繁或稀疏小震滑动为特征．未来复发中强以上地震的可能性较小。     

Emplacement age and tectonic implications of the brecciated limestone at the edge of the Longmenshan klippe

The Longmenshan thrust belt (LMTB) is one of the best natural laboratories for thin-skinned tectonics and has developed a series of NE-SW trending fold-and-thrust structures represented by a series of nappes and klippes, exemplified by the Tangbazi and Bailuding klippe. However, the timing and emplacement mechanism of these klippes are still in dispute. Three possible mechanisms have been proposed: (1) a Mesozoic-Cenozoic southeastward thrusting, (2) a Cenozoic gravity gliding, and (3) glacial deposition. Almost all of these klippes are tectonic and overlaid on folded Late Triassic sandstone except the Tangbazi klippe, which is located in the center of the LMTB and has a narrow tail extending southeastward and covering Jurassic-Quaternary rocks. This geometric relationship is considered the most important stratigraphic evidence to support the post-Cenozoic emplacement of the Longmenshan klippe. Our structural and petrological observations show that the rocks at the front of the Tangbazi and Bailuding structures are brecciated limestone, which is assumed to have been generated by a gravitational collapse and is not characteristic of the massive Permian strata. Artemisia pollen, which has been exclusively recognized in post-Late Eocene strata in Central Asia, was found in the matrix of this brecciated limestone. Therefore, our discovery indicates that the brecciated limestone was deposited after the Late Eocene rather than during the Permian as annotated on the geological map. In contrast, unbrecciated, massive Permian limestone overlaid on the folded Late Triassic rocks. Hence, the anomalous relationship of Permian strata overlaying Late Triassic rocks cannot be evidence of Cenozoic emplacement. According to currently recognized bulk strata relationships, we can only be sure that the klippe was emplaced in the post Late Triassic. The petrological characteristics of the brecciated limestone show that it was crumbled before the re-sedimentation of the breccia, implying that the LMTB might have experienced a rapid uplift during the Late Eocene.     

中扬子江汉平原簰洲湾地区中、新生代构造-热演化史

本文综合运用磷灰石-锆石裂变径迹和（U-Th）/He、镜质体反射率及盆地模拟等手段,深入细致地探讨了中扬子江汉平原簰洲湾地区中、新生代构造-热史演化过程.研究结果表明,研究区中-新生代大规模构造抬升剥蚀、地层冷却事件始于早白垩世（140-130 Ma）;大规模抬升冷却过程主要发生在早白垩世中后期至晚白垩世.研究区虽然可能存在一定厚度的晚白垩世-古近纪地层沉积,总体沉积规模相对较小.综合分析认为,区内应该存在较大厚度的中侏罗统或/和上侏罗统乃至早白垩世地层的沉积;而现今残存中生代中、上侏罗统地层相对较薄,主要是由于后期持续构造抬升剥蚀造成的,估计总剥蚀厚度约4300 m左右.区内中生代地层在早白垩世达到最大古地温,而不是在古近纪沉积末期;上三叠统地层最大古地温在170~190℃之间.热史分析结果表明,区内古生代古热流相对稳定,平均热流在53.64 mW·m^-2;早侏罗世末期古热流开始降低,在早白垩世初期古热流约为48.38 mW·m^-2.     

河西走廊西段及邻区主要断裂（一）-晚新生代逆断层与走滑断层的地震剖面解释

基于地震剖面解释的构造分析表明，河西走廊西段及邻区发育有许多晚第三纪-第四纪的逆断层与走滑断层. 其主要类型有两种:一是与北祁连逆冲推覆作用有关的南倾逆断层，其走向北西，主要分布于北祁连山东北缘及河西走廊西南部地区；二是与阿尔金断裂活动有关的逆断层与走滑断层，主要分布于红柳峡、宽台山——合黎山地区. 这些断层与新生代始新世末期以来印-藏碰撞的远距离效应有关. 它们于晚第三纪开始活动，主要活动于第四纪时期，而且大多目前仍在活动，属于活动性断层，是河西走廊地区地震的潜发因素. 此外，它们还造成了地层的强烈变形，形成了一系列的地貌阶地和河流的水平错移.      

On the faults of western Hexi Corridor and its nearby regions, northwestern China:Thrust faults and strike-slip faults of Late Cenozoic

Introduction Hexi Corridor, a corridor extended over 1 000 km and with a strike of WNW-ESE, is locatedbetween Alxa uplift and northern Qilianshan Caledonian folding belt of northern Qinghai-Xizang(Tibet) Plateau (Figure 1). In the paper, we will discuss the regions between Altun fault and Yu-mushan of the western Hexi Corridor, where the climate is arid, which results in sparse vegetation,but abundant oil and gas resource, and being one of the most important petroleum industry base…     

南海南部海域中中新世(T3界面)构造变革界面地震反射特征及构造含义

南海南部海域油气资源丰富,由于盆地沉积厚度大、沉积相横向变化快和构造演化复杂等原因,致使该海域新生代地层的划分方案差异大,地层时代的认识也存在较大分歧,这极大地制约了对盆地油气资源评价的正确认识.本文在总结国内外不同分层方案基础上,通过收集国外在南海南部深水区两口关键钻井的资料,开展曾母和北康两盆地重处理二维地震剖面的构造-地层解译,以及联井剖面的井震对比,重新识别和标定新生代重要构造变革面的地震反射特征.根据海域钻井、地层岩性、沉积环境、构造应力体系和古生物资料的综合对比研究,结合婆罗洲陆地测年结果和区域构造事件,重新厘定中中新世T₃构造变革面的发育时代,年龄为15～17 Ma,分析了该界面的构造含义,认为其是南海海底扩张停止的一个构造响应界面,在南海南部海域对应南沙运动,在北婆罗洲地区表现为沙巴造山运动.     

The structure of Circum-Tibetan Plateau Basin-Range System and the large gas provinces

Northward subduction of the Cenozoic Tethys ocean caused the convergence and collision of Eurasia-Indian Plates, resulting in the lower crust thickening, the upper crust thrusting, and the Qinghai-Tibet uplifting, and forming the plateau landscape. In company with uplifting and northward extruding of the Tibetan plateau, the contractional tectonic deformations persistently spread outward, building a gigantic basin-range system around the Tibetan plateau. This system is herein termed as the Circum-Tibetan Plateau Basin-Range System, in which the global largest diffuse and the most energetic intra-continental deformations were involved, and populations of inheritance foreland basins or thrust belts were developed along the margins of ancient cratonic plates due to the effects of the cratonic amalgamation, crust differentiation, orogen rejuvenation, and basin subsidence. There are three primary tectonic units in the Circum-Tibet Plateau Basin-Range System, which are the reactivated ancient orogens, the foreland thrust belts, and the miniature cratonic basins. The Circum-Tibetan Plateau Basin-Range System is a gigantic deformation system and particular Himalayan tectonic domain in central-western China and is comparable to the Tibetan Plateau. In this system, northward and eastward developments of thrust deformations exhibit an arc-shaped area along the Kunlun-Altyn-Qilian-Longmenshan mountain belts, and further expand outward to the Altai-Yinshan-Luliangshan-Huayingshan mountain belts during the Late Cenozoic sustained collision of Indo-Asia. Intense intra-continental deformations lead ancient orogens to rejuvenate, young foreland basins to form in-between orogens and cratons, and thrusts to propagate from orogens to cratons in successive order. Driven by the Eurasia-Indian collision and its far field effects, both deformation and basin-range couplings in the arc-shaped area decrease from south to north. When a single basin-range unit is focused on, deformations become younger and younger together with more and more simple structural styles from piedmonts to craton interiors. In the Circum-Tibetan Plateau Basin-Range System, it presents three segmented tectonic deformational patterns: propagating in the west, growth-overthrusting in the middle, and slip-uplifting in the east. For natural gas exploration, two tectonic units, both the Paleozoic cratonic basins and the Cenozoic foreland thrust belts, are important because hydrocarbon in central-western China is preserved mainly in the Paleozoic cratonic paleo-highs and the Meso-Cenozoic foreland thrust belts, together with characteristics of multiphrase hydrocarbon generation but late accumulation and enrichment.     

Episodic Cenozoic volcanism and tectonism in the Andes of Peru

Radiometric and geologic information indicate a complex history of Cenozoic volcanism and tectonism in the central Andes. K-Ar ages on silicic pyroclastic rocks demonstrate major volcanic activity in central and southern Peru, northern Chile, and adjacent areas during the Early and Middle Miocene, and provide additional evidence for volcanism during the Late Eocene. A provisional outline of tectonic and volcanic events in the Peruvian Andes during the Cenozoic includes: one or more pulses of igneous activity and intense deformation during the Paleocene and Eocene; a period of quiescence, lasting most of Oligocene time; reinception of tectonism and volcanism at the beginning of the Miocene; and a major pulse of deformation in the Middle Miocene accompanied and followed through the Pliocene by intense volcanism and plutonism. Reinception of igneous activity and tectonism at about the Oligocene-Miocene boundary, a feature recognized in other circum-Pacific regions, may reflect an increase in the rate of rotation of the Pacific plate relative to fixed or quasifixed mantle coordinates. Middle Miocene tectonism and latest Tertiary volcanism correlates with and probably is genetically related to the beginning of very rapid spreading at the East Pacific Rise.     

Structural material complexes in the Late Cenozoic Udokan lava plateau: Patterns of distribution and rock associations

We provide a new scheme to classify Late Cenozoic volcanic rocks in the Udokan lava plateau based on isotope datings of rocks derived during the last 15 years. The scheme distinguishes five structural-material complexes (SMCs): Middle Miocene, Late Miocene, Early/Middle Pliocene, Late Pliocene, and Quaternary. Each SMC has its ejecta of central-type eruptions and subvolcanic emplacement episodes that classify themselves into individual rock complexes, while the ejecta of mass fissure effusions from three SMCs (the Late Miocene, the Early/Middle Pliocene, and the Late Pliocene) can be lumped into three stratigraphic series. Each series includes three suites, with the middle position (in the series section) being occupied by suites composed of basaltic melt differentiates.     

Mesozoic basin evolution and tectonic mechanism in Yanshan, China

The Mesozoic basins in Yanshan, China underwent several important tectonic transformations, including changes from a pre-Late Triassic marginal cratonic basin to a Late Triassic-Late Jurassic flexural basin and then to a late Late Jurassic-Early Cretaceous rift basin. In response to two violent intraplate deformation at Late Triassic and Late Jurassic, coarse fluvial depositional systems in Xingshikou and Tuchengzi Formations were deposited in front of thrust belts. Controlled by transform and extension faulting, fan deltas and lacustrine systems were deposited in Early Cretaceous basins. The composition of clastic debris in Late Triassic and Late Jurassic flexural basins respectively represents unroofing processes from Proterozoic to Archean and from early deposited, overlying pyroclastic rocks to basement rocks in provenance areas. Restored protobasins were gradually migrated toward nearly NEE to EW-trending from Early Jurassic to early Late Jurassic. The Early Cretaceous basins with a NNE-trending crossed over early-formed basins. The Early-Late Jurassic and Early Cretaceous basins were respectively controlled by different tectonic mechanisms.     

Late Cenozoic sedimentary process and its response to the slip history of the central Altyn Tagh fault,NW China

The ENE-striking Altyn Tagh fault (ATF), extending along the northern edge of the Ti-betan Plateau, is one of the major important strike-slip faults, and has been known as one of the key areas to debate the eastward extrusion and crustral shortening models of the Tibetan Plateau during and after India-Asia collision. This paper mainly presents new evidence of Late Cenozoic sedimentary process to reconstruct the slip history of the ATF during the Late Cenozoic. Field measurements and laboratory analyses of the sedimentary characteristics in the Late Cenozoic basins in the central Altyn Tagh fault suggest that Late Cenozoic sedimentary sequence should be divided into three units according to facies changes. The paleo-topography reconstruction shows that the sedimentarion in these basins was tightly related with the fault, indicating that the ATF has experienced at least three stages of strike slipping in the Late Cenozoic. New geological data from the Late Cenozoic sedimentary basins and the formation of the present Suo’erkuli basin provide evidence for the displacement of the fault. The result shows that the 80–100 km left-lateral strike-slip displacement of the fault has been accumulated in the Late Cenozoic.