青藏高原挤压隆升过程的数值模拟   总被引：36，自引：7，他引：29       下载免费PDF全文

傅容珊  徐耀民  黄建华  李力刚 《地球物理学报》2000,43(3):346-355

将大陆岩石层视为由幂指数律控制的一层薄层,它上伏在粘滞性较低的软流层之 上蠕变流动,其运动限制在与东亚大陆构造形态较相似的边界模型的梯形框架之中．设印度 板块以一恒定的速度向北推进,并被视为青藏高原挤压隆升的主要动力．用数值模拟的方法 研究了青藏高原的挤压隆升演化过程,并对数值模拟的隆升过程作了剥蚀修正．结果表明, 由挤压模型所产生的地形和现代青藏高原及其邻区的地形格局比较吻合．同时也表明,挤压 隆升过程受多种因素（如岩石层的力学特性、边界条件以及剥蚀作用）的制约,无论从空间还 是从时间上看,模拟所反映的高原隆升都是不均匀的演化过程．  相似文献   

Timing and mechanisms for the generation and modification of the anomalous topography of the Borborema Province,northeastern Brazil     

J.M. Morais Neto  K.A. Hegarty  G.D. Karner  F.F. Alkmim 《Marine and Petroleum Geology》2009

The results of apatite fission-track analysis in 14 granitic-gneissic samples from two regional transects across the Borborema Plateau, northeastern Brazil, show evidence for two dominant paleothermal events: a Late Cretaceous cooling event beginning sometime between 100 and 90 Ma, and a second cooling event in the Neogene. The distribution of the fission-track results suggests that the cooling events have a broad regional expression and are consistent with the geologic record in the Araripe Basin, western Borborema Province, which attests to a post-Albian uplift of the whole region. We hypothesize that the first event is due to the uplift and denudation of regional, permanent topography generated after the breakup of Brazil and Africa. Such topography is predicted by models of continental margin extension in which continental lithosphere thinning is followed by thickening of the adjacent hinterland lithosphere and crust (Kusznir, N.J., Karner, G.D., 2007. Continental lithospheric thinning and breakup in response to upwelling divergent mantle flow: application to the Woodlark, Newfoundland and Iberia margins. In: Karner, G.D., Manatschal, G., Pinheiro, L. (Eds), Imaging, mapping and modeling continental lithosphere extension and breakup. Special Publication 282, Geological Society, London, pp. 389–419.). In northeastern Brazil, this extension-engendered topography may have been amplified by magmatic underplating related to the Saint Helena and Ascension plumes. The Miocene cooling event (20–0 Ma) occurred at a time characterized by the transition from carbonate ramp to progradational clastic systems on the Pernambuco–Paraíba margin and the offshore Potiguar Basin. This same stratigraphic response characterizes the Neogene stratigraphy of many passive margins and attests to a global increase in the delivery of clastics to margins, the simplest explanation of which is a climate change that accentuated erosion of pre-existing topography. Thus, the present rugged landscape of northeastern Brazil is interpreted to be a product of this younger denudation event. A corollary of this study is that the history, distribution and delivery of clastics to the northern and northeastern margins of Brazil are a function of the regional development of the continental landscape during the Late Cenozoic.  相似文献   

甘肃崖湾金矿微量元素特征及矿床剥蚀程度研究   总被引：3，自引：0，他引：3       下载免费PDF全文

姜启明  李岳 《甘肃地质》2005,14(1):27-32

崖湾金矿床定位于礼县—白云—山阳深大断裂西端的分支断裂罗坝—礼县断裂中段,是李坝大型金矿床的外围矿床之一。通过对矿区水系沉积物、岩石微量元素特征的总结,结合地质因素,指出矿床的主要微量元素为As、Bi、Sb、Ag、Hg。与Au矿关系密切的伴生元素依次为Sb、As、Ag、Hg、Bi。矿床微量元素具有垂直分带性,从上至下的序列为:Ag—Mo—Hg—Pb—Bi—Sb—Au—As—Zn—Cu。对矿体标高和微量元素垂直分带性的研究后认为矿床总体剥蚀程度为上部,矿床向西、向东发展潜力巨大。  相似文献   

Gypsum karst intensification as a consequence of sulphur mining activity (Jaziv field,Western Ukraine)     

Myroslav Sprynskyy  Mariya Lebedynets  Andrzej Sadurski 《Environmental Geology》2009,57(1):173-181

The scope of this study is to evaluate the parameters of the gypsum–anhydrite strata karstification under the influence of the quarry exploitation of Jaziv sulphur field (West Ukraine) accompanying by drainage. The quarry drainage provoked the enormous depression cone forming with 100 km² in area and the corresponding intensification of chemical denudation of the gypsum–anhydrite strata. The gypsum karstification rate for the 29-year period of the quarry drainage was 0.06% with the dissolved rock volume of 1,328,507 m³ that is about 80 times higher than in natural conditions. For the drainage period (29 years) the karst denudation rate was 17,952 m³/km² against the natural background of 231.3 m³/km². The absolute value of artificial denudation for the studied massif area is 1.79 cm for 29 years or 0.062 mm/year while the denudation rate under natural conditions would be 0.231 cm for 29 years or 0.0008 mm/year. The forecasted volumes of the surface-evident collapses are evaluated using the relationship between the calculated amount of dissolved sulphate rocks and volumes of the current surface-evident collapses. According to this evaluation, the current collapses correspond to about 34% only from the dissolved rocks volume calculated for the drainage period.  相似文献   

The impact of diamond extraction on natural denudation rates in the Diamantina Plateau (Minas Gerais,Brazil)     

《Journal of South American Earth Sciences》2014

The ¹⁰Be method was used to investigate the effect of mining activities on the natural denudation rates in alluvial sediments from catchments of the Southern Espinhaço Range (SER) in Minas Gerais State (Brazil). In this region, which is predominantly composed of quartzites, the ¹⁰Be concentrations were measured in alluvial sediments from catchments in a preserved natural area of the Serra do Cipó National Park and on the Diamantina Plateau, which was subjected to diamond extraction from beginnings of XVIII century until the end of the XX. Two types of drainage were identified in the Diamantina Plateau area: (i) reworked drainage (alluvial sediments reworked by panning) and (ii) overloaded drainage (alluvial sediments originating from panning processes on saprolites located upstream). The mean denudation value for the natural drainages (∼4.4 m.My-1) is similar to that of the reworked drainages (∼4.3 m.My-1) However, the denudation rates obtained for eleven samples from three sites in overloaded basins range from ∼6.4 m My-1 to ∼22.8 m My-1 and are thus higher than those determined for the reworked and natural basins. These results show that despite the alluvium deposits have been intensely reworked by panning, the values of denudation rates were not changed, they are similar to denudation rates from the natural drainages. However, the natural rates are lower than those affected by panning processes on saprolites.  相似文献   

Patterns and estimates of post-Rupelian burial and erosion in the Campine area,north-eastern Belgium     

《Physics and Chemistry of the Earth》2013

We have compiled a dataset containing information on patterns of burial and erosion that occurred during the last ca. 30 Ma in the Campine area, north-eastern Belgium. This area coincides with the occurrence of the Rupelian Boom Clay which is considered as one of the potential host formations for radwaste disposal. Patterns and estimates of erosion and sedimentation, based on geological and geomorphological data, from several locations within the Boom Clay outcrop and subcrop zone, show increasing burial in northern and north-eastern direction over the last 30 Ma. More southern areas have experienced erosion and denudation during some geological stages, usually in the order of several 10 m, up to 100 m at most at two discrete locations. During the Quaternary, erosion is a widespread phenomenon in the Campine area, except in the Roer Valley Graben. The obtained estimates of erosion and burial are compared and discussed in the context of the overall geodynamic evolution of north-western Europe.  相似文献   

Estimates of present-day erosion based on sediment transport in rivers: a case study in Taiwan     

Fung-Chun Li  Jacques Angelier  Rou-Fei Chen  Hui-Ming Hsieh  Benoît Deffontaines  Ching-Ruey Luo  Tso-Tchang Wu  Ming-Chao Lin 《Comptes Rendus Geoscience》2005,337(13):1131-1139

We discuss the present-day sediment transport by rivers, and hence the erosion rate in upstream basins, based on the example of Taiwan Rivers where large datasets are available. After data correction, the values of the suspended sediment load in the lower Kaoping River are nearly three times smaller than those from the literature. On the other hand, we add the bed load evaluated from numerical modelling, despite limitations from data and models. Whereas the contribution of the chemical denudation rate in Taiwan is minor, the bed load is significant and must be evaluated. We point out that biases in data collection may favour high values of suspended load data, and that large series of datasets are needed to reduce uncertainties and smooth the time variability effect. To cite this article: F.-C. Li et al., C. R. Geoscience 337 (2005).  相似文献   

Regional relief characteristics and denudation pattern of the western Southern Alps, New Zealand     

Oliver Korup  Jochen Schmidt  Mauri J. McSaveney 《Geomorphology》2005,71(3-4):402-423

The Southern Alps of New Zealand are the topographic expression of active oblique continental convergence of the Australian and Pacific plates. Despite inferred high rates of tectonic and climatic forcing, the pattern of differential uplift and erosion remains uncertain. We use a 25-m DEM to conduct a regional-scale relief analysis of a 250-km long strip of the western Southern Alps (WSA). We present a preliminary map of regional erosion and denudation by overlaying mean basin relief, a modelled stream-power erosion index, river incision rates, historic landslide denudation rates, and landslide density. The interplay between strong tectonic and climatic forcing has led to relief production that locally attains 2 km in major catchments, with mean values of 0.65–0.68 km. Interpolation between elevations of major catchment divides indicates potential removal of l0¹–10³ km³, or a mean basin relief of 0.51–0.85 km in the larger catchments. Local relief and inferred river incision rates into bedrock are highest about 50–67% of the distance between the Alpine fault and the main divide. The mean regional relief variability is ± 0.5 km.Local relief, valley cross-sectional area, and catchment width correlate moderately with catchment area, and also reach maximum values between the range front and the divide. Hypsometric integrals show scale dependence, and together with hypsometric curves, are insufficient to clearly differentiate between glacial and fluvial dominated basins. Mean slope angle in the WSA (ψ = 30°) is lower where major longitudinal valleys and extensive ice cover occur, and may be an insensitive measure of regional relief. Modal slope angle is strikingly uniform throughout the WSA (φ = 38–40°), and may record adjustment to runoff and landsliding. Both ψ and φ show non-linear relationships with elevation, which we attribute to dominant geomorphic process domains, such as fluvial processes in low-altitude valley trains, surface runoff and frequent landsliding on montane hillslopes, “relief dampening” by glaciers, and rock fall/avalanching on steep main-divide slopes.  相似文献   

剥蚀法计算GPS观测网独立环闭合差   总被引：1，自引：0，他引：1  

刘根友 《测绘工程》2001,10(1):33-36

在GPS测量中，往往需要计算三角形、多边形闭合差，以便及时发现观测粗差、衡量GPS观测精度。本文提出了剥蚀法计算GPS观测网独立环闭合差，这种方法利用计算机自动确定观测网中的独立环个数，并计算所有独立环闭合差。它适合各种复杂的观测图形，所计算的独立环个数是唯一的，独立环为观测网中的最小闭合单元，并且环与环之间不出现包含和重复。  相似文献   

矿床变化与保存研究的裂变径迹新途径   总被引：3，自引：0，他引：3  

王建平  翟裕生  刘家军  柳振江  刘俊 《地球科学进展》2008,23(4):421-427

矿床形成后的变化与保存是矿床学研究与找矿勘探中一项极其重要但仍需进一步加强的基础性工作。影响矿床变化与保存的众多因素中,区域隆升与剥蚀是最为关键的因素之一。裂变径迹法是研究区域隆升与剥蚀的一种有效手段,它能为我们提供剥蚀速率以及剥蚀量的定量数据。一些产于花岗质岩体内与岩体有成因联系的矿床,其成矿深度可以通过详细的流体包裹体研究来获得。通过成矿深度与岩体剥蚀深度对比分析,能使我们更好地了解矿床形成后变化保存条件。裂变径迹法与流体包裹体研究相结合是矿床形成后变化与保存研究一种切实可行的方法。  相似文献