南海大陆边缘动力学:科学实验与研究进展   总被引：13，自引：4，他引：9       下载免费PDF全文

李家彪 《地球物理学报》2011,54(12):2993-3003

国家重点基础研究发展计划(973)项目(2007CB411700)首次在南海南部大陆边缘及西南次海盆开展长排列大震源多道地震、海底地震仪(OBS)折射/反射地震等的综合地球物理探测,结合地质构造、地球化学、动力模拟等的综合研究,形成如下重要认识:南海海盆新生代发生了早、晚两期海底扩张.早期扩张发生于33.5～25 Ma...  相似文献   

GPS无线电掩星后向传播方法          下载免费PDF全文

徐贤胜  黄思训  郭鹏  洪振杰 《地球物理学报》2011,54(9):2193-2200

在大气多路径传播条件下,讨论了两种无线电信号的反演方法:几何光学方法和后向传播方法.当大气存在多路径效应时,采用几何光学方法反演大气参数会引入较大误差.后向传播方法将无线电信号从多路径区域反推至单路径区域,减少了大气多路径效应的影响.为了比较不同的反演方法,利用多相位屏模型,数值模拟了大气多路径条件下无线电信号在大气中...  相似文献   

3-D geomechanical restoration and paleomagnetic analysis of fault-related folds: An example from the Yanjinggou anticline,southern Sichuan Basin     

《Journal of Structural Geology》2013

We examine the development of the Yanjinggou anticline, a fault-propagation-fold in the southern Longmen Shan, through an integrated study of structural geometry, strain, and paleomagnetism. The 3-D structural and strain restoration models generated in our analysis reveal that the NE-trending Yanjinggou fold has a curved map trace that is convex to the southeast. The fold has three distinct regions characterized by different strain patterns: contraction in the core of the fold, extension in the outer arc, and a forelimb with distributed shear. To further understand the kinematics of the Yanjinggou anticline, we performed paleomagnetic analysis on 184 oriented samples collected across the structure. Anisotropy of magnetic susceptibility (AMS) measurements and stepwise thermal demagnetization were conducted. A strike test was applied to the high temperature component (HTC) in order to identify rotation around the arc. The result indicates that the Yanjinggou anticline is a progressive arc, with a minor initial curvature and a dominant secondary curvature related to vertical-axis rotation synchronous with thrusting. The primary curvature and initial development of the structure correlates with the growth of the southern Longmen Shan in Late Miocene. The secondary curvature correlates with displacement extending since Late Pleistocene toward the southeast into the central basin along the detachments that underlie the structure. Lateral gradients in displacement along this underlying detachment provide a mechanism for producing the vertical rotation of the anticline. AMS results and historical earthquake analysis imply that the fault-propagation fold, along with other NE trending structures in the southern Sichuan basin, are tectonically active and accommodate east-west crustal shortening in the basin. By integrating 3-D structural and strain restoration modeling with systematic AMS and paleomagnetic methods using statistical analysis, we closely constrain how the Yanjinggou anticline developed, and provide insights into the formation of fault-related folds with curved shapes in map view, which are common in other fold-and-thrust belts around the world.  相似文献   

黔西南灰家堡金矿田成矿构造特征研究   总被引：12，自引：3，他引：9  

邱小平  孟凡强  于波  任卫波 《矿床地质》2013,32(4):783-793

灰家堡矿田中水银洞等金矿床具有极高的矿石品位,成为卡林型金矿床特例.通过矿田构造与矿床地质研究,结合CSAMT深部探测,文章提出了灰家堡背斜为含金超压流体上拱形成的气液热隆褶曲,含金超压流体沿背斜轴部破裂带和盲断裂爆破上涌,交代上覆围岩形成高品位的层控型和断裂型金矿体的成矿模式,中二叠统与上二叠统之间岩溶不整合构造(构造蚀变体)作为深部含矿流体的中转聚集站,本身也赋存大规模的金矿体,据此提出了多方位的深部成矿预测方案.  相似文献   

塔里木盆地塔北隆起英买2号背斜的成因机制与构造模型   总被引：1，自引：0，他引：1       下载免费PDF全文

张宁宁  何登发  孙方源  桂宝玲 《地质科学》2013,(1):133-148

英买力低凸起位于塔北隆起西部,是重要的含油气区域。英买2号背斜的研究与认识对于揭示区域构造演化及南部多个内幕型碳酸盐岩背斜的成因机制具有重要意义。本文运用断层相关褶皱原理及平衡剖面等方法,对英买2号背斜的地震剖面进行解释及复原。研究表明,英买2号背斜为固定翼长的滑脱褶皱,滑脱面位于中寒武统下部塑性层中,背斜演化经历了宽缓斜坡、起伏南倾、构造逆冲、稳定沉降掩埋和调整改造等5个阶段。背斜开始隆升时间为奥陶纪末期,地层缩短量为400～700 m,在海西末期隆升后遭受严重剥蚀,后期发育具传播性质的断层,伴有2期生长构造发育,背斜的前翼发生翼部旋转,发育生长三角,后翼有上超现象,体现了不同时期沉积速率的变化,也反映了后期构造活动的阶段性与持续性。  相似文献   

Spores from a carboniferous section in the hunter valley,New South Wales     

Geoffrey Playford  Robin Helby 《Australian Journal of Earth Sciences》2013,60(1):103-119

In this initial systematic study of Carboniferous spores from New South Wales, Australia, fifteen species (all but one of them new) are formally described and are distributed among eight established genera and two new genera (Rattiganispora, a distally annulate trilete form, and Psomospora, an inaperturate or proximally hilate form). The species were selected as being the most characteristic and distinctive forms found in the Italia Road Formation at its well‐exposed type section in the Hunter Valley, east‐central New South Wales. The formation is a cyclical non‐marine unit, over 300 metres (1,000 ft) thick, consisting of lithic arenites together with carbonaceous shales, claystones, and siltstones; its age is regarded as West‐phalian‐Stephanian. The microfiora is compared with those known from sediments of similar age elsewhere and its place in the Australian Palaeozoic palynostratigraphic record is discussed.

New specific institutions are as follows: Punctatisporites lucidulus, P. sub‐tritus, Verrucosisporites aspratilis, V. italiaensis, Raistrickia accincta, R. radiosa, Reticulatisporites asperidictyus, R. magnidictyus, Foveosporites pellucidus, Rattiganispora apiculata (type species), Kraeuselisporites kuttungensis, Grandispora maculosa, Psomospora detecta (type species), and Wilsonites australiensis.  相似文献   

Structure of an active foreland fold and thrust belt,Papua New Guinea     

M. S. Craig  K. Warvakai † 《Australian Journal of Earth Sciences》2013,60(5):719-738

Geological structure of the active foreland fold and thrust belt of Papua New Guinea has been interpreted using high-quality seismic-reflection data. Three en échelon anticlines, the Strickland, Cecilia and Wai Asi, are located along the frontal margin of the Papuan Fold Belt. All three are foreland-vergent and cut by hinterland-dipping thrust faults that sole into a common detachment beneath the Oligocene to Miocene Darai Limestone. Two of the anticlines are linked by a right-lateral transfer zone. Folding occurs primarily in the upper 2000 m of strata, which consist of Darai Limestone overlain by Miocene to Quaternary siliciclastic sedimentary rocks. Beneath the Darai Limestone lies the less-competent shaly Ieru Formation, which exhibits disharmonic folding and variable bed thickness. Seismic-reflection data clearly show that the Plio-Pleistocene upper Era Beds are deformed to the same extent as the underlying Darai Limestone, demonstrating that most of the observed deformation has occurred during the Late Pliocene and Pleistocene.  相似文献   

Neoproterozoic evolution of the basement of the South-American platform     

《Journal of South American Earth Sciences》2013

Neoproterozoic geologic and geotectonic processes were of utmost importance in forming and structuring the basement framework of the South-American platform. Two large domains with distinct evolutionary histories are identified with respect to the Neoproterozoic era: the northwest-west (Amazonian craton and surroundings) and the central-southeast (the extra-Amazonian domain).In the first domain, Neoproterozoic events occurred only locally and were of secondary significance, and the geologic events, processes, and structures of the pre-Neoproterozoic (and syn-Brasiliano) cratonic block were much more influential. In the second, the extra-Amazonian domain, the final evolution, structures and forms are assigned to events related to the development of a complex net of Neoproterozoic mobile belts. These in turn resulted in strong reworking of the older pre-Neoproterozoic basement. In this domain, four distinct structural provinces circumscribe or are separated by relatively small pre-Neoproterozoic cratonic nuclei, namely the Pampean, Tocantins, Borborema and Mantiqueira provinces. These extra-Amazonian provinces were formed by a complex framework of orogenic branching systems following a diversified post-Mesoproterozoic paleogeographic scenario. This scenario included many types of basement inliers as well as a diversified organization of accretionary and collisional orogens. The basement inliers date from the Archean to Mesoproterozoic periods and are different in nature. The escape tectonics that operated during the final consolidation stages of the provinces were important to and responsible for the final forms currently observed. These latest events, which occurred from the Late Ediacaran to the Early Ordovician, present serious obstacles to paleogeographic reconstructions.Two groups of orogenic collage systems are identified. The older system from the Tonian (>850 Ma) period is of restricted occurrence and is not fully understood due to strong reworking subsequent to Tonian times. The second group of orogenies is more extensive and more important. Its development began with diachronic taphrogenic processes in the Early Cryogenian period (ca. 850–750 Ma) and preceded a complex scenario of continental, transitional and oceanic basins. Subsequent orogenies (post 800 Ma) were also created by diachronic processes that ended in the Early Ordovician. More than one orogeny (plate interaction) can be identified either in space or in time in every province. The orogenic processes were not necessarily synchronous in different parts of the orogenic system, even within the same province. This particular group of orogenic collage events is known as the “Brasiliano”.All of the structural provinces of the extra-Amazonian domain exhibit final events that are marked by extrusion processes, are represented by long lineaments, and are fundamental to unraveling the structural history of the Phanerozoic sedimentary basins.  相似文献   

造山过程重力塌陷与褶皱作用——面理弯切轴与褶皱轴面数据对比研究          下载免费PDF全文

曹汇 《中国地质》2013,40(6):1818-1828

提要：美国东部阿巴拉契亚造山带北端缅因州Rangeley地区志留—泥盆纪中温低压片岩测得的面理弯切轴与褶皱轴面数据有很好的对应关系。西部科迪勒拉造山带落基山脉南端科罗拉多州阿肯色河地区Texas Creek 以东高温低压前寒武纪堇青石片岩中测得的褶皱轴面方向和片理走向数据与该地区堇青石、斜长石变斑晶内测得的5期面理弯切轴也表现出很好的一致性。而在Rangeley北东200 km的佛蒙特州Chester Dome地区奥陶—泥盆纪中温中压片麻岩中测得的类似褶皱轴面数据却只反映了该地区5期面理弯切轴中较晚的北北西-南南东走向和北北东-南南西走向的两期面理弯切轴,未测得与其余3期面理弯切轴对应的褶皱轴面数据。通过对变质峰期温度相近、压力不同的两个造山带内3个典型变质岩区面理弯切轴、褶皱轴面方向和片理走向数据的对比分析认为,造山作用发生的地壳深度差异是早期褶皱经历多期造山运动后能否保存下来的主要影响因素。重力形成的去褶皱作用使得早期形成的规模较小褶皱经历复杂造山过程后难以保存。区域内早期形成的规模较大褶皱和造山过程晚期形成的褶皱由于受到重力塌陷作用影响较小,所以能够较好保存下来。  相似文献   

基于MODIS图像的内孤立波信息反演——以南海北部深水区为例     

黄晓冬  赵玮 《中国海洋大学学报(自然科学版)》2014,44(7):19-23

卫星遥感技术是探测海洋内孤立波的重要手段,目前提取内孤立波特征参数的工作均使用SAR图像。本文首次探讨了基于MODIS可见光图像的内孤立波信息反演方法,并对位于南海北部水深3 000m左右的内孤立波个例进行了研究,发现其振幅为124m,传播速度为3.14m/s,半波宽度为3 258m。根据潜标现场观测结果对反演得到的内孤立波信息进行了检验,结果表明,此方法具有较高的准确度,为研究南海北部深水区内孤立波提供了一条新的可行路径。  相似文献