Tectonic controls on carbonate sequence formation in an active strike–slip setting: Serranilla Basin, Northern Nicaragua Rise, Western Caribbean Sea     

David S. Duncan  Albert C. Hine  Andre W. Droxler 《Marine Geology》1999,160(3-4):355-382

The Serranilla Basin is a flat-floored, semi-circular bathymetric depression (100×100 km; 1100–1200 m deep) at the western end of the northern Nicaragua Rise (NNR) in the Caribbean Sea. It is bound to the north by the Cayman Trough, an area of active sea floor spreading, and is part of the Northern Caribbean Plate Boundary Zone (NCPBZ). Single-channel, high-resolution seismic data were calibrated to rock dredges and ODP Site 1000 to define the geologic evolution and attempt to tie sequence formation within the basin to tectonic developments in this part of the Caribbean. Five seismic sequences were identified within the basin. The two lower sequences (A and B) are interpreted as neritic and shallow periplatform deposits which infill three distinct basins that make up the early to late Miocene Serranilla Basin. The three upper sequences (C through E) are interpreted as periplatform and pelagic deposits interspersed with turbidites, and in some areas, megabreccias. Faulting is prevalent in sequences A through C in the central basin, and becomes progressively younger toward the south, disrupting the seafloor in places and perhaps indicating renewed activity along the Pedro Fracture Zone. The timing of sequence boundary formation has been correlated to tectonic activity along the NCPBZ and closure of the Central American Seaway. Possible mechanisms of sequence boundary formation include tectonic tilting within the basin in conjunction with increased turbidite deposition, carbonate platform drowning and subsequent back-stepping associated with circulation changes resulting from tectonic ‘gateway' closure, and megabreccia deposition associated with bank demise. Although a direct genetic relationship is not proven, regional tectonic changes are considered more important than eustatic sea-level changes in controlling depositional sequence formation in the Serranilla Basin.  相似文献   

Isochores and 3-D visualization of rising and falling slat diapirs     

Giovanni GuglielmoJr  Bruno C. Vendeville  Martin P. A. Jackson 《Marine and Petroleum Geology》1999,16(8):181

Diapir fall, which was predicted by physical models, has been identified in salt provinces, such as the South Atlantic margins, the North Sea, and the Paradox Basin (Colorado–Utah). However the 3-D geometry of falling diapirs and their country rock is still poorly understood. 3-D visualization and isochore patterns from a physical model help elucidate this geometry.The model initially comprised a unit of viscous silicone overlain by a prekinematic sand unit. Sand units representing brittle sediments were deposited episodically during gravity gliding and spreading. Regional extension triggered and eventually widened salt walls, causing them to sag. The 3-D visualization shows that regional hydrocarbon migration, which tends to be seaward during diapir rise and landward during diapir fall, can potentially be orthogonal to local migration along grabens at soft-linked zones of relay ramps. Furthermore, anticlinal culminations may form (1) in horsts that bend along strike and (2) adjoining the fork of Y-shaped salt walls.Sequential isochore maps of the overburden show how patterns of sedimentation, deformation, and underlying salt thickness changed through time. Isochores of prekinematic units record only strain: thinned belts record early extension. In contrast, isochores of synkinematic units record mostly thickness variations due to deposition on actively deforming topography. Isochores above sagging diapirs identify the thickest part of crestal depocenters, where the most rapid sagging occurred in regions of maximum extension near the unbuttressed downdip part of the gravity-spreading system. Additionally, asymmetric isochore patterns may reveal underlying half-grabens or tilted symmetric grabens. In relay systems, overlying isochores may indicate which part of a salt wall rose to compensate for sagging elsewhere in the relay.  相似文献   

Morphotectonic zones along the coast of the Pacific continental margin, southern Mexico     

María-Teresa Ramírez-Herrera  Jaime Urrutia-Fucugauchi   《Geomorphology》1999,28(3-4)

Geomorphic analysis, employing topographic, morphologic, geologic, and bathymetric maps, and field studies show that the morphology of the southern coast of Mexico can be linked to lateral variations in the geometry and tectonism of the subduction zone. A reconnaissance study, based on the regional morphological characteristics and correlation with seismotectonic segments, regional tectonics and major bathymetric features, allows identification of several morphotectonic zones along the coast of southern Mexico: (1) Jalisco zone, (2) Colima zone, (3) Michoacan zone, (4) Guerrero zone, (5) Oaxaca zone, and (6) Tehuantepec zone. A range of geomorphological evidence, including marine terraces, river terraces, uplifted notches, and elevated wave-cut platforms, indicates local and regional uplift along the coast of the Jalisco, Michoacan, Guerrero and Oaxaca zones. Coasts of the Colima and Tehuantepec zones show morphological evidence of subsidence.  相似文献   

Shear heating in continental strike-slip shear zones:model and field examples   总被引：5，自引：0，他引：5  

Philippe Hervé Leloup  Yannick Ricard  Jean Battaglia  & Robin Lacassin 《Geophysical Journal International》1999,136(1):19-40

  相似文献   

活动大陆边缘的板片窗构造   总被引：7，自引：0，他引：7  

李三忠  郭晓玉  侯方辉  吕海青  金宠  刘保华 《海洋地质前沿》2004,20(11):6-18

正俯冲的洋中脊的持续扩张作用将会使该洋中脊两侧的洋壳板片之间形成一个持续加宽的间隙,这个间隙称为板片窗。板片窗往往形成于小于10Ma左右具浮力的大洋岩石圈俯冲时期。板片窗形态依赖于3个主要因素：板块的相对运动、俯冲前的洋脊一转换断层组合样式、俯冲角度。影响板片窗形态的次要因素还有热侵蚀、相变等因素。在板片窗出现的活动大陆边缘,软流圈、岩石圈、大气圈、水圈发生独特的多圈层相互作用,是地球系统最为活跃的地带。由于该地带的洋底消减往往与生长轴呈一定角度相交,不仅引起盆地的不对称消减,而且使得板片窗之上的活动大陆边缘的构造、岩浆、成矿和热效应明显不同于洋中脊平行于俯冲带的消减作用产生的构造、岩浆、成矿和热效应。  相似文献   

廊固凹陷深部剪切破裂构造的地震学证据   总被引：2，自引：0，他引：2       下载免费PDF全文

李赫  董一兵  王熠熙  彭研枫  刘双庆  吴博洋 《地球物理学报》2020,63(2):492-504

基于区域地震台网观测数据,采用近震波形反演方法,确定2018年2月12日河北永清M4.3地震的最佳双力偶源震源机制解为:节面Ⅰ走向297°,倾角58°,滑动角-32°;节面Ⅱ走向45°,倾角63°,滑动角-144°;是一个略带正断分量的右旋走滑地震.结合近震转换波测定主震的震源深度在19km附近.地震序列的双差定位结果显示:永清地震序列震中呈北东向窄带展布,表明此次地震主要向北东向破裂;深度集中分布在17～19km,整体形态近于铅直,显示发震断裂具有走向北东、倾向南东、倾角陡立的特征,与节面Ⅱ的性质比较吻合,推测节面Ⅱ为发震断层面.将发震断层面参数与震源区附近断裂性质进行对比分析,形成了关于廊固凹陷附近区域地震构造的一些认识:(1)推测永清地震的发震构造不是地壳浅部发育的先存正断裂,而是震源区下方一条地壳尺度的深断裂,该深断裂为新生断裂,具有右旋走滑正断性质,倾角陡峭、近于直立、宽度较大,向上与夏垫断裂相通.(2)综合震源区附近多条深地震反射剖面探测结果,推测永清地震的发震断裂与新夏垫断裂同属一条断裂,称为:新夏垫深断裂.该断裂从夏垫向西南方向延伸至文安,并可能与霸县—束鹿—邯郸断裂带相联系,总长度超过150km.(3)基于2006年文安M5.1地震与2018年永清M4.3地震在震源机制上的相似性及震源位置上的关联性,结合区域构造条件,认为两次地震的发震构造均为新夏垫深断裂.(4)根据研究区几次显著地震的震源深度分布特征,参考区域断层构造、电性结构和流变学模型,推测活化克拉通块体新生断裂的脆韧性转换界面深度在15km附近.  相似文献   

青藏高原地球物理与大陆动力学研究的新进展   总被引：2，自引：0，他引：2       下载免费PDF全文

李秋生  高原  王绪本  赵俊猛 《地球物理学报》2020,63(3):789-801

岩石圈地球物理探测、深部结构成像与各向异性等研究是青藏高原大陆动力学研究的基础.近年来,随着深部地球物理探测技术和反演成像技术的进步,信息提取与细节分辨能力不断提升,青藏高原壳幔结构、碰撞和隆升动力学、资源与地质灾害的深部机制等研究进展显著.本专辑收录33篇论文,主要分布在深部结构与地球物理探测、地震各向异性与变形、断裂性质与地震活动等三个主要研究领域.本文重点围绕这些论文,对近年来青藏高原地球物理研究进展进行综述.  相似文献   

APPLICATION OF DEM GENERATION TECHNOLOGY FROM HIGH RESOLUTION SATELLITE IMAGE IN QUANTITATIVE ACTIVE TECTONICS STUDY: A CASE STUDY OF FAULT SCARPS IN THE SOUTHERN MARGIN OF KUMISHI BASIN          下载免费PDF全文

WANG Si-yu  AI Ming  WU Chuan-yong  LEI Qi-yun  ZHANG Hui-ping  REN Guang-xue  LI Chuan-you  REN Zhi-kun 《地震地质》2018,40(5):999-1017

Traditional method to generate Digital Elevation Model (DEM)through topographic map and topographic measurement has weak points such as low efficiency, long operating time and small range. The emergence of DEM-generation technology from high resolution satellite image provides a new method for rapid acquisition of large terrain and geomorphic data, which greatly improves the efficiency of data acquisition. This method costs lower compared with LiDAR (Light Detection and Ranging), has large coverage compared with SfM (Structure from Motion). However, there is still lack of report on whether the accuracy of DEM generated from stereo-imagery satisfies the quantitative research of active tectonics. This research is based on LPS (Leica Photogrammetry Suit)software platform, using Worldview-2 panchromatic stereo-imagery as data source, selecting Kumishi Basin in eastern Tianshan Mountains with little vegetation as study area. We generated 0.5m resolution DEM of 5-km swath along the newly discovered rupture zone at the south of Kumishi Basin, measured the height of fault scarps on different levels of alluvial fans based on the DEM, then compared with the scarp height measured by differential GPS survey in the field to analyze the accuracy of the extracted DEM. The results show that the elevation difference between the topographic profiles derived from the extracted DEM and surveyed by differential GPS ranges from -2.82 to 4.87m. The shape of the fault scarp can be finely depicted and the deviation is 0.30m after elevation correction. The accuracy of measuring the height of fault scarps can reach 0.22m, which meets the need of high-precision quantitative research of active tectonics. It provides great convenience for rapidly obtaining fine geometry, profiles morphology, vertical dislocations of fault and important reference for sites selection for trench excavation, slip rate, and samples. This method has broad prospects in the study of active tectonics.  相似文献   

格尔木—额济纳旗断面走廊域火成岩－构造组合与大地构造演化   总被引：6，自引：0，他引：6  

邓晋福  杨建军  赵海玲  赖绍聪  刘厚祥  罗照华  狄永军 《现代地质》1996,10(3):330

摘要：主要基于火成岩组合讨论了大地构造演化。提出碰撞型蓝片岩是大洋闭合与陆－陆碰撞作用的产物和标志,白云母／二云母花岗岩是陆内俯冲作用的岩石学记录,以钾玄岩系列为主的火成岩组合是水平缩短式陆内造山带边界的标志,造山末期Ａ型花岗岩是造山带崩塌的标志。重建了祁连山—柴达木地区与北山地区的构造演化和造山过程。讨论了新生代陆内造山－岩浆作用,提出了青藏－喜马拉雅陆内造山火成岩的成对性,由此探索了陆内造山过程  相似文献   

DEEP TECTONIC STRESS CHANGE BASED ON LONG-TERM APPARENT RESISTIVITY TIME SERIES: A CASE STUDY FROM NORTH SECTION OF YISHU FAULT ZONE          下载免费PDF全文

WANG Qing-lin  SUN Huai-feng  ZHU Cheng-lin  ZHANG Ji-hong  TANG Ting-mei 《地震地质》2017,39(1):147-157

Almost all the destructive earthquakes, so called tectonic earthquake, are produced by tectonic movement. The tectonic movement will cause resistivity changes in the earth. It's valuable for strong earthquake forecast to study the relationship between the resistivity change and tectonic movement. According to magnetotelluric sounding method, we establish a robust estimate method to calculate the long-term apparent resistivity from seismic station monitoring data. We first use 1D layered earth models to test the sensitivity of this method. Then we process the continually observed long term electromagnetic data in 4 years (from 2011 to 2014) from Anqiu seismic station which is very close to the north section of Yishu fault zone. The apparent resistivity curves and the apparent resistivity time series for different frequencies are obtained. The time series show the resistivity increase in the selected 4 years, which is in good agreement with the GPS baseline data. This also satisfies the results from rock mechanics experiments on deep rocks (upper mantle) that the resistivity will increase with improved stress in a high temperature and pressure environment. The method is valuable for studying electromagnetic precursor of strong earthquakes and strong earthquake prediction.  相似文献