共查询到20条相似文献，搜索用时 31 毫秒
1.
2.
河西走廊—祁连山北缘地区地处青藏高原北缘,受印度板块与欧亚板块中生代末—新生代早期的碰撞及持续至今的向北推挤作用的远程效应的影响,该地区是现今的地壳活动地区,其中地壳形变是最主要的表现形式。地壳形变监测显示,隆起区垂直位移速率最大可达15mm/a,沉降区最大位移速率为-15mm/a。祁连山和河西走廊的相对隆升变化与该区地震具有密切的关系,河西走廊相对下降、祁连山相对隆升的后期是地震多发时期,河西走廊相对隆升、祁连山相对下降的后期是地震少发时期,这与该区处于挤压体制下的区域构造背景密切相关。GPS水平位移监测显示,河西走廊—祁连山北缘地区全区都一致向东位移,且位移速率非常大,大者大于10mm/a;位移速率具有南部大于北部、东部大于西部的特点,水平位移速率变化与现代活动断裂具有非常密切的关系,并以主要断裂构造为区带的边界;水平位移速率矢量与2002年玉门地震的震源机制解所显示的沿地震破裂面发生的滑动方向非常一致。 相似文献
3.
In the past two years, the National Geodetic Survey has been creating a data base of vertical crustal movement information. The data elements are relative elevation changes along lines of releveling which are used to produce graphic displays on microfilm. In separate studies, the releveling data, together with information extracted from mareograph records, have been used to create two networks of velocity differences. The two networks, one in the vicinity of Chesapeake Bay and the other covering the Gulf Coast states, have been adjusted in order to prepare maps showing the velocities of elevation change. In the adjustments, the velocities derived from mareograph records were treated as observations. The results indicate annual subsidence ranging between −1.2 mm and −4.0 mm in the Chesapeake Bay area, with significant local variation. In the Gulf Coast region there is generally slight subsi'dence along the coast, ranging between 0.0 and −1.5 mm/year. Stability and slight uplift is indicated to the north where bedrock reaches the terrain surface. Anomalous subsidence of −7.0 mm/year occurs at New Orleans, La., and at Houston, Texas, there has been several decimeters change in the last ten years. 相似文献
4.
Rob Westaway David R. Bridgland 《Boreas: An International Journal of Quaternary Research》2014,43(2):505-527
Reversals in vertical crustal motion, alternations between uplift and subsidence over time scales of hundreds of thousands of years or more, have been identified in Late Cenozoic fluvial sequences in many regions worldwide. They form a class of fluvial archive that is distinct from the extreme stability observed in Archaean cratons and the monotonic uplift or subsidence that is widely observed in other regions. Such alternations between uplift and subsidence are characteristic of regions of Early or Middle Proterozoic crust, where the initial crustal consolidation included the development of a thick ‘root’ of mafic material at the base of the crust; the present study focuses on localities with this crustal type in the USA and eastern Europe. It has previously been suggested on the basis of uplift modelling that this style of crustal behaviour occurs only in regions where the mobile lower‐crustal layer is relatively thin. This study supports this conclusion on the basis of independent geothermal calculations, which indicate that such alternations between uplift and subsidence occur where the mobile lower‐crustal layer is ≤～7 km thick. An understanding of this phenomenon, in relation to the understanding of vertical crustal motions induced by surface processes (and thus by climate change) in general, therefore requires analysis of the properties and dynamics of the mobile lower‐crustal layer; detailed analysis of fluvial sequences thus contributes unique information in this area. 相似文献
5.
H.G. Henneberg 《Tectonophysics》1986,130(1-4):105-124
The study area is one section of the Tia Juana Oilfield on the east shore of Lake Maracaibo in Venezuela. It has an area of about 45 km2. The absolute vertical subsidence component attains 4 m, due to the oil extraction in the last 50 years. Some years ago, the boundary area of the subsidence cone showed cracks in the earth's surface. The length of the crackline is about 4 km. Strong horizontal movements were observed along this rupture zone. To study the horizontal component of the earth-surface movement, a high-precision traverse network was installed and measured, the first time in June 1978 and reobserved in December 1978. In 1984 another measurement compaign was carried out which permitted a comparison of the results of the two epochs. To know the behavior of the affected field better, a three-dimensional representation of horizontal and vertical measurements, including the orientation of the resultant vector, was made. 相似文献
6.
随着社会经济的快速发展,黄河三角洲地区普遍发生了地面沉降,已经成为了影响区域社会经济可持续发展的重要因素之一。本文以黄河三角洲地面沉降典型地段—滨州地区为研究对象,以该区2005~2019年年间共计6期地面沉降监测数据为基础,对区内多年来地面沉降发展演变规律进行分析,对地面沉降成因机理进行研究,并根据滨州地下水系统的水文地质条件以及地面沉降机理,概化出滨州地下水系统水位地质概念模型及地面沉降模型。在此模型基础上推演建立滨州地下水开采与地面沉降三维数值模型。利用该模型对地面沉降与地下水位监测数据进行内插外推计算,综合计算结果分析和研究,对地面沉降和地下水动态进行预测预警,从而为黄河三角洲地区地面沉降防治提供依据。 相似文献
7.
宁德三都澳位于福建省东部沿海,口小腹大水深,为中国乃至世界罕见天然良港,阐述全新世以来,三都澳的地壳沉降规律、新构造运动特征,分析三都澳在全新世（1万年）以来,以及全新世晚期（三千多年）来,澳内沉降速率,淤积物等情况,认为三都澳成为世界性良港原因,是地壳沉降作用整体大于澳内淤积物。 相似文献
8.
Data from the nation-wide GPS continuous tracking network that has been operated by the Geographical Survey Institute of Japan since April 1996 were used to study crustal deformation in the Japanese Islands. We first extracted site coordinate from daily SINEX files for the period from April 1, 1996 to February 24, 2001. Since raw time series of station coordinates include coseismic and postseismic displacements as well as seasonal variation, we model each time series as a combination of linear and trigonometric functions and jumps for episodic events. Estimated velocities were converted into a kinematic reference frame [Heki, K., 1996. Horizontal and vertical crustal movements from three-dimensional very long baseline interferometry kinematic reference frame: implication for reversal timescale revision. J. Geophys. Res., 101: 3187–3198.] to discuss the crustal deformation relative to the stable interior of the Eurasian plate. A Least-Squares Prediction technique has been used to segregate the signal and noise in horizontal as well as vertical velocities. Estimated horizontal signals (horizontal displacement rates) were then differentiated in space to calculate principal components of strain. Dilatations, maximum shear strains, and principal axes of strain clearly portray tectonic environments of the Japanese Islands. On the other hand, the interseismic vertical deformation field of the Japanese islands is derived for the same GPS data interval. The GPS vertical velocities are combined with 31 year tide gage records to estimate absolute vertical velocity. The results of vertical deformation show that (1) the existence of clear uplift of about 6 mm/yr in Shikoku and Kii Peninsula, whereas pattern of subsidence is observed in the coast of Kyushu district. This might reflect strong coupling between the Philippine Sea plate and overriding plate at the Nankai Trough and weak coupling off Kyushu, (2) no clear vertical deformation pattern exists along the Pacific coast of northeastern Japan. This might be due to the long distance between the plate boundary (Japan trench) and overriding plate where GPS sites are located, (3) significant uplift is observed in the southwestern part of Hokkaido and in northeastern Tohoku along the Japan Sea coast. This is possibly due to the viscoelastic rebound of the 1983 Japan Sea (Mw 7.7) and the 1993 Hokkaido–Nansei–Oki (Mw 7.8) earthquakes and/or associated with distributed compression of incipient subduction there. We then estimate the elastic deformation of the Japanese Islands caused by interseismic loading of the Pacific and Philippine Sea subduction plates. The elastic models account for most of the observed horizontal velocity field if the subduction movement of the Philippine Sea Plate is 100% locked and if that of the Pacific Plate is 70% locked. However, the best fit for vertical velocity ranges from 80% to 100% coupling factor in southwestern Japan and only 50% in northeastern Japan. Since horizontal data does not permit the separation of rigid plate motion and interplate coupling because horizontal velocities include both contributions, we used the vertical velocities to discriminate between them. So, we can say there is strong interplate coupling (80%–100%) over the Nankaido subduction zone, whereas it is about 50% only over the Kurile–Japan trench. 相似文献
9.
Jack E. Staples 《Tectonophysics》1986,130(1-4):171-177
Whether monitoring crustal movements in localized volcanic areas along known fault lines, or over large crustal-movement areas, the geodesist has been restricted by the measurement accuracy of the instruments used, the accumulation of errors, the lack of reliable air refraction information and the problem of finding proper measurement procedures and mathematical solutions to assure that the inherent errors of the measurement-mathematical procedures do not exceed any conceivable ground movement.
Recent technological advances have placed new instruments and systems at the disposal of the geodesist, so that is now feasible to measure and analyze these micro and macro crustal movements within the accuracies required.
The paper describes three such systems:
1. (1) The Wild Electronic Theodolite T-2000 with a highly precise distance-measurement instrument, the DI-4S, together with a data collector, the GRE-3, which are connected to a computer and a plotter to measure and analyze both micro and macro crustal movements.
2. (2) The Wild NAK-2 level with an antimagnetic compensator which increases the accuracy in the height/velocity monitoring of vertical crustal movements by virtual elimination of the influence of natural or man-made magnetic fields on the automatic level.
3. (3) The use of analytical photogrammetry employing both terrestrial and aerial photography to monitor crustal movements.
By taking advantage of these new instruments and systems, the scientists capability to provide crustal movement data for use in the analysis and prediction of micro or macro crustal movement is greatly enhanced. 相似文献
10.
珊瑚礁是发育于热带海洋环境中由生物作用和地质作用共同形成的地质体,具有独特的新构造运动意义。南海西北部珊瑚礁记录所反映的新构造运动主要有火山活动、地壳升降运动和地震活动等。珊瑚礁区第四纪火山活跃,到现代已停止活动,部分火山构成珊瑚礁的基座,个别出露海面为火山岛;地壳升降运动差异较大,雷州半岛西南部珊瑚礁呈上升趋势,上升率为0.02~0.05mm/a;西沙群岛等岛礁地壳运动则呈下降趋势,下降率为-0.07~-0.10mm/a,岛礁中的造礁石珊瑚生长率、礁顶和灰沙岛的堆积率均相当于或大于地壳下降率与现代海平面上升率的总和;南海西北部珊瑚礁区内地震活动较强,尤其是1994年12月31日和1995年1月10日在雷州半岛西南部海域发生了6.1级和6.2 级地震,这两次地震对该区珊瑚礁的发育有较大的影响。 相似文献
11.
The Tokai district in central Japan is located close to the convergent boundary between the Philippine Sea and Eurasian plates, and has experienced not only repeated large interplate earthquakes but also intense aseismic movement. In this paper, the spatial and temporal tectonic evolution of the Tokai district, particularly around the Omaezaki area, is discussed to assess whether the district has been and will be active or inactive. According to a geological survey, the horizontal crustal shortening strain can imply the hypothetical tectonic model that the area has been getting less active and the strain rate since the Neogene can be calculated as 12% and 2×10−6%/year, respectively. The present interseismic horizontal crustal strain and strain rate around the Omaezaki area are approximately 4×10−7% and 4×10−9%/year. By comparing these rates, the decrease since Neogene can imply the hypothetical tectonic model that the area has been getting less active influenced by the strain partitioning between the Suruga Trough and the Zenisu Thrust. 相似文献
12.
澄合矿区煤系地层沉积环境及成煤条件分析 总被引：2，自引：0，他引：2
以大量勘探钻孔资料及野外观测为基础，对澄合矿区煤系地层沉积环境及成煤条件进行了分析研究，阐述了本区煤系主要在岸线附近的滨海平原及近海内陆环境沉积。其中滨海及泻湖波浪带最有利于成煤，因受地壳近南北向不均衡沉积的控制，区内煤系及煤层变化多呈南北向带状分布，为今后的地质勘探和煤矿开采提供了依据。 相似文献
13.
We conducted a seismic tomographic analysis to estimate the crustal structure beneath the Shikoku and Chugoku regions in Japan. The Philippine Sea slab (PHS slab) subducts continuously in a SE–NW direction beneath this region, and the crustal structure is complex. Furthermore, the Median Tectonic Line (MTL), one of the longest and most active arc-parallel fault systems in Japan (hereafter, the MTL active fault system), is located in this area, and the right-lateral strike–slip movement of this fault system is related to the oblique subduction of the PHS slab. The MTL active fault system has ruptured repeatedly during the last 10 000 years, and has high seismic potential. Our tomographic analysis clarified the heterogeneous crustal structure along the MTL active fault system. This fault system in Shikoku can be divided into two segments, an east segment and a west segment, on the basis of the velocity structure. This segmentation model is consistent with other such models that have been determined from geological and geomorphological data such as fault geometry, slip rate, and faulting history. This consistency suggests that the surface characteristics of the MTL active fault system are related to structural properties of the crust. In particular, a prominent low-velocity (low-V) zone is present in the lower crust beneath the east segment. Our tomographic images show that the lower crust structure beneath the east segment is obviously different from that of the other segment. Furthermore, this low-V zone may indicate the presence of fluid, possibly related to dehydration of the PHS slab. As the presence of fluid in the lower crust affects the activity of the fault, stress accumulation and the fault failure mechanism may differ between the two segments of the MTL active fault system. 相似文献
14.
前人对三峡工程库区地壳运动与阶地类型的研究结果认为是间歇性抬升和基座阶地。文章从滑坡研究入手,对奉节白衣庵滑坡前沿深切古河湾中保存良好阶地的第四纪不同岩性沉积物的沉积关系、沉积年代、沉积气候等进行了重点研究;对云阳宝塔—鸡扒子滑坡及其附近的汤溪河口阶地与类型、阶（台）地沉积关系、沉积年代与成因、岩性等进行了对比分析;另外,对奉节白衣庵和云阳宝塔—鸡扒子两滑坡与河谷发育、深切河槽的发育关系、形成时代进行了讨论;同时还对旧县坪、故陵滑坡的发生年龄与其上阶地进行了分析。研究结果表明,峡区西云阳—奉节一带T1和T2阶地均为内叠（嵌入）阶地,地壳运动在最近50万年期间有4次上升,3次下降,在总体呈上升的背景下,近12万年期间升降幅度较前降低,频度则增加。此外,还讨论了与地壳运动、阶地形成有关的滑坡与河谷发育关系,发现深切河槽的形成时间是30万年前的MIS9早中期;白衣庵、宝塔、旧县坪等大滑坡均是河谷深槽形成后发生的;证实“40～30kaB·P.的高温大降水”时期是古洪水发生期外,还存在更早期的古洪水沉积。 相似文献
15.
Annemiek Vink Holger Steffen Lutz Reinhardt Georg Kaufmann 《Quaternary Science Reviews》2007,26(25-28):3249-3275
A comprehensive observational database of Holocene relative sea-level (RSL) index points from northwest Europe (Belgium, the Netherlands, northwest Germany, southern North Sea) has been compiled in order to compare and reassess the data collected from the different countries/regions and by different workers on a common time–depth scale. RSL rise varies in magnitude and form between these regions, revealing a complex pattern of differential crustal movement which cannot be solely attributed to tectonic activity. It clearly contains a non-linear, glacio- and/or hydro-isostatic subsidence component, which is only small on the Belgian coastal plain but increases significantly to a value of ca 7.5 m relative to Belgium since 8 cal. ka BP along the northwest German coast. The subsidence is at least in part related to the Post-Glacial collapse of the so-called peripheral forebulge which developed around the Fennoscandian centre of ice loading during the Last Glacial Maximum. The RSL data have been compared to geodynamic Earth models in order to infer the radial viscosity structure of the Earth's mantle underneath NW Europe (lithosphere thickness, upper- and lower-mantle viscosity), and conversely to predict RSL in regions where we have only few observational data (e.g. in the southern North Sea). A very broad range of Earth parameters fit the Belgian RSL data, suggesting that glacial isostatic adjustment (GIA) only had a minor effect on Belgian crustal dynamics during and after the Last Ice Age. In contrast, a narrow range of Earth parameters define the southern North Sea region, reflecting the greater influence of GIA on these deeper/older samples. Modelled RSL data suggest that the zone of maximum forebulge subsidence runs in a relatively narrow, WNW–ESE trending band connecting the German federal state of Lower Saxony with the Dogger Bank area in the southern North Sea. Identification of the effects of local-scale factors such as past changes in tidal range or tectonic activity on the spatial and temporal variations of sea-level index points based on model-data comparisons is possible but is still complicated by the relatively large range of Earth model parameters fitting each RSL curve, emphasising the need for more high-quality observational data. 相似文献
16.
西准噶尔地区晚古生代岩浆活动剧烈,地壳的垂向和侧向增生显著,地壳生长和演化存在多阶段性。本文重点通过Sr-Nd-Pb同位素填图研究,发现西准噶尔地区εNd(t)值为2.29~8.75,(87Sr/86Sr)i值为0.697 397~0.708 336,(206Pb/204Pb)i值为17.4975~19.0352,整体表现为高正εNd(t)、低(87Sr/86Sr)i和年轻的地壳模式年龄特征,源区以古生代新生地壳为主,地幔贡献值整体大于50%,深部地壳几乎不存在古老的结晶基底,可以与区域构造地质、地球物理资料作较好匹配。区域晚古生代主要经历3个时期的造山阶段,分别对应造山带演化的第一阶段(中晚石炭世,岛弧为代表的侧向生长为主)、第二阶段早期(晚石炭世—早二叠世,后碰撞阶段的垂向生长为主)和第二阶段晚期(早二叠世—早三叠世,壳幔混源背景下的垂向生长),区域造山作用结束于早三叠世。 相似文献
17.
叠加于弧后前陆盆地挠曲沉降之上的另一类沉降——动力沉降 总被引：2，自引：0，他引：2
弧后前陆盆地挠曲沉降包括逆冲负载沉降和盆地沉积物负载沉降。叠加于挠曲沉降之上还存在另一类沉降,即动力沉降。动力沉降是动力地形的一种,即动力地形低。动力地形一般认为具有两种成因,一种为与超大陆集聚和分散有关的动力地形,另一种为与大洋板片俯冲有关的动力地形。由大洋板块俯冲产生的动力沉降往往分布于弧后前陆盆地区,其幅度、波长与板块俯冲角度、俯冲速率、俯冲板块在地幔中通过的位置和俯冲岩石圈的热年代密切相关。将通过弧后前陆盆地沉积地层的去压实得到的总沉降减去盆地模拟获得的逆冲带负载和盆地沉积物负载沉降可以得到剩余沉降,即动力沉降。从地层资料中定量分离出动力沉降为改进和限制长期以来悬而未决的由洋壳俯冲导致的地幔-粘性流动构造模型提供理论基础和实际资料。 相似文献
18.
Shujun Ye Yue Luo Jichun Wu Xuexin Yan Hanmei Wang Xun Jiao Pietro Teatini 《Hydrogeology Journal》2016,24(3):695-709
Shanghai, in China, has experienced two periods of rapid land subsidence mainly caused by groundwater exploitation related to economic and population growth. The first period occurred during 1956–1965 and was characterized by an average land subsidence rate of 83 mm/yr, and the second period occurred during 1990–1998 with an average subsidence rate of 16 mm/yr. Owing to the establishment of monitoring networks for groundwater levels and land subsidence, a valuable dataset has been collected since the 1960s and used to develop regional land subsidence models applied to manage groundwater resources and mitigate land subsidence. The previous geomechanical modeling approaches to simulate land subsidence were based on one-dimensional (1D) vertical stress and deformation. In this study, a numerical model of land subsidence is developed to simulate explicitly coupled three-dimensional (3D) groundwater flow and 3D aquifer-system displacements in downtown Shanghai from 30 December 1979 to 30 December 1995. The model is calibrated using piezometric, geodetic-leveling, and borehole extensometer measurements made during the 16-year simulation period. The 3D model satisfactorily reproduces the measured piezometric and deformation observations. For the first time, the capability exists to provide some preliminary estimations on the horizontal displacement field associated with the well-known land subsidence in Shanghai and for which no measurements are available. The simulated horizontal displacements peak at 11 mm, i.e. less than 10 % of the simulated maximum land subsidence, and seems too small to seriously damage infrastructure such as the subways (metro lines) in the center area of Shanghai. 相似文献
19.
Ian Shennan 《第四纪科学杂志》1986,1(2):155-179
Stratigraphic, micropalaeontologic and radiocarbon data show that since c. 6500 BP the Fenland has been influenced by 7 periods of positive sea-level tendencies and by 6 periods of negative sea-level tendencies. Despite the numerous problems associated with the reconstruction of past altitudes of sea level the periods of positive sea-level tendencies were clearly characterised by a rise in sea level, the development of transgressive overlaps and a landward movement of the coastline. The periods of negative sea-level tendencies were characterised by the development of regressive overlaps, a seaward movement of the coastline and a reduced or negative rate of sea-level rise. The various altitudinal errors do not permit the incontrovertible distinction of periods of falling sea levels. All changes within the Fenland were not synchronous and local factors influenced the exact nature of each sea-level indicator. Dominant regional and local factors have been identified for different areas and different time periods. The chronological and spatial characteristics of the sequences within the Fenland are best explained by a palaeocoastline without supratidal barriers controlling sedimentation. The data indicate an average crustal subsidence in the Fenland of 0.9m/1000 years since c. 6500 BP and the pattern of positive and negative tendencies of sea-level movement is also seen in the chronologies for north west England and north east Scotland. 相似文献
20.
青藏高原班公-怒江缝合带现今运动状况的GPS观测研究 总被引：2，自引：0，他引：2
利用青藏高原改则地区一条跨越班公-怒江缝合带的10站GPS剖面在2007-2009年的3期流动观测资料,采用自洽的统一参考框架方法分析研究了改则地区的现今地壳差异运动,得出该区域现今地壳应变率以南北向挤压为主,量值达(104.0±28.6)×10-9/a,同时兼有东西向拉张,量值约为(25.4±17.7)×10-9/a。利用半无限弹性空间的断裂位错模型和GPS速度矢量的约束,反演获得班公－怒江缝合带在该地区（即改则-洞错断裂）的现今运动以右旋走滑为主,走滑速率约为(7.4±0.8) mm/a。 相似文献