Mantle heat flow and geotherms for major tectonic units in central Europe     

Jacek Majorowicz 《Pure and Applied Geophysics》1978,117(1-2):109-123

The results of seismic measurements along the deep seismic sounding profile VII and terrestrial heat flow measurements used for construction of heat generation models for the crust in the Paleozoic Platform region, the Sudetic Mountains (Variscan Internides) and the European Precambrian Platform show considerable differences in mantle heat flow and temperatures. At the base of the crust variations from 440–510°C in the models of Precambrian Platform to 700–820°C for the Paleozoic Platform and the Variscan Internides (Sudets) are found. These differences are associated with considerable mantle heat flow variations.The calculated models show mantle heat flow of about 8.4–12.6 mW m^–2 for the Precambrian Platform and 31 mW m^–2 to 40.2 mW m^–2 for Paleozoic orogenic areas. The heat flow contribution originating from crustal radioactivity is almost the same for the different tectonic units (from 33.5 mW m^–2 to 37.6 mW m^–2). Considerable physical differences in the lower crust and upper mantle between the Precambrian Platform and the adjacent areas, produced by lateral temperature variations, could be expected. On the basis of carbon ratio data it can be concluded that the Carboniferous paleogeothermal gradient was much lower in the Precambrian Platform area than in the Paleozoic Platform region.  相似文献   

Coupled HM analysis using zero‐thickness interface elements with double nodes—Part II: Verification and application     

J. M. Segura  I. Carol 《国际地质力学数值与分析法杂志》2008,32(18):2103-2123

In a companion Part I of this paper (Int. J. Numer. Anal. Meth. Geomech. 2008; DOI: 10.1002/nag.735 ), a coupled hydro‐mechanical (HM) formulation for geomaterials with discontinuities based on the finite element method (FEM) with double‐node, zero‐thickness interface elements was developed and presented. This Part II paper includes the numerical solution of basic practical problems using both the staggered and the fully coupled approaches. A first group of simulations, based on the classical consolidation problem with an added vertical discontinuity, is used to compare both the approaches in terms of accuracy and convergence. The monolithic or fully coupled scheme is also used in an application example studying the influence of a horizontal joint in the performance of a reservoir subject to fluid extraction. Results include a comparison with other numerical solutions from the literature and a sensitivity analysis of the mechanical parameters of the discontinuity. Some simulations are also run using both a full non‐symmetric and a simplified symmetric Jacobian matrix. On top of verifying the model developed and its capability to reflect the conductivity changes of the interface with aperture changes, the results presented also lead to interesting observations of the numerical performance of the methods implemented. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Micromorphological features of Paleo-Stagnic-Anthrosols at archaeological site of Sanxingdui,China     

Yurong He  Chengmin Huang  Xiangming Xu  Yanqiang Wang  Xiubin He 《山地科学学报》2008,5(4):358-366

The archaeological site of the Sanxingdui may date back as far as 5,000 years ago. The typical profiles of Palaeo-Stagnic-Anthrosols near the ancient site were selected, which aimed to identify diagnostic horizons employing methodology of soil taxonomic classification and to reveal the micromorphological properties of the paleosols. Under long-term anthropogenic mellowing, the discernible differentiation between anthrostagnic epipedon and its subhorizons as well as hydragric horizon and its subhorizons occurred in Paleo-Stagnie-Anthrosols at the archaeological site of the Sanxingdui. The mieromorphological properties diversified among each specific diagnostic subhorizon, e.g., the developed microstructure in cultivated subhorizon within anthrostagnic epipedon, closely arranged particles and considerable micropores beneficial to both of water conservation and filtration in plow subhorizon within anthrostagnic epipedon, and automorphic optical-orientation clays and calcareous corrosion in hydragric horizons. The findings above of micromorphological features related with diagnostic horizons are significant for soil taxonomic classification.  相似文献   

A complex variable solution for stress and displacement field around a lined circular tunnel at great depth     

Ming‐Bin Wang  Shu‐Cai Li 《国际地质力学数值与分析法杂志》2009,33(7):939-951

By applying the series expansion technique in the complex variable method established by Muskhelishvili, the plane elasticity problem for the stress and displacement field around a lined circular tunnel in conjunction with the consideration of misfit and interaction between the liner and the surrounding geomaterial is dealt with. The tunnel is assumed to be driven in a homogeneous and isotropic geomaterial. The coefficients in the Laurent series expansion of the stress functions are determined. The complex potentials in the liner and the surrounding geomaterial are explicitly derived, respectively. As an example, the case of a lined circular tunnel located in an isotropic initial stress field but subjected to uniform internal pressure is numerically considered. Numerical results indicate that the installation of tunnel liner can reduce the influences of the tunnel excavation on the in situ displacement and stress fields. However, the relative thickness and rigidity of the liner should be in an appropriate range. In addition, the effect of the tunnel excavation upon the displacement field is more significant than that upon the stress field. As far as the stress field in the surrounding geomaterial is concerned, when the ratio between the cover depth of tunnel and the tunnel radius is larger than 5, the results for the stress field in the paper are applicable. When the ratio between the tunnel depth and the tunnel radius is larger than 20, the results are applicable for the displacement field. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Autochthonous block fields in southern Norway: Implications for the geometry,thickness, and isostatic loading of the Late Weichselian Scandinavian ice sheet     

Atle Nesje  Svein Olaf Dahl 《第四纪科学杂志》1990,5(3):225-234

The consistent geographical and altitudinal distribution of autochthonous block fields (mantle of bedrock weathered in situ) and trimlines in southern Norway suggests a multi-domed and asymmetric Late Weichselian ice sheet. Low-gradient ice-sheet profiles in the southern Baltic region, in the North Sea, and along the outer fjord areas of southern Norway, are best explained by movement of ice on a bed of deforming sediment, although water lubricated sliding or a combination of the two, may not be excluded. The ice-thickness distribution of the Late Weichselian Scandinavian ice sheet is not in correspondence with the modern uplift pattern of Fennoscandia. Early Holocene crustal rebound was apparently determined by an exponential, glacio-isostatic rise. Later, however, crustal movements appear to have been dominated by large-scale tectonic uplift of the Fennoscandian Shield, centred on the Gulf of Bothnia, the region of maximum lithosphere thickness.  相似文献   

大气河对2013年“7.9”四川盆地持续性暴雨作用的诊断分析     

岳俊  李国平 《成都信息工程学院学报》2015,30(2)

2013年7月7～11日,四川盆地大部分地区出现了持续性强降雨天气(以下简称四川“7.9”暴雨).此次过程的降水中心稳定少动、降水强度及总量大、持续时间长,累积降水量最高达到了1000ram以上,造成严重灾害.为分析位于孟加拉湾地区的大气河对四川“7.9”暴雨的影响.利用NCEP/NCAR再分析资料,通过研究孟加拉湾大气河水汽对这次暴雨的作用及影响,得到的结果表明:此次持续性暴雨过程中,孟加拉湾大气河受西太平洋副高东撤影响,并在200 hPa和850 hPa高低空急流的共同作用下,不断向四川地区输送水汽.这种水汽输送一直持续到11日才停止,此时降水也趋于结束.在整个暴雨过程中,850 hPa上孟加拉湾大气河输送的水汽由于云贵高原阻挡,而绕开云贵高原在南海地区与西太副高外围的水汽以及南半球的越赤道气流汇合后,在低空急流左侧辐合气流作用下输送到四川盆地,为暴雨产生提供水汽.同时,700 hPa上的水汽直接越过云贵高原到达四川盆地.孟加拉湾大气河的这两种输送方式为四川盆地持续性暴雨提供了充足的水汽供应.  相似文献   

渤海西部2次赤潮过程的气象因子对比分析     

段宇辉  王文  景华  郭志强 《海洋预报》2015,32(1)

利用加密自动站资料、NCEP/NCAR 1°×1°再分析资料、海表温度(SST)资料和常规观测资料等气象资料,对2009年5月31日—6月13日和2012年5月18—28日发生在渤海西部海域的2场相似气象因子影响下的典型高影响赤潮过程进行了对比分析。初步结果表明:(1)2场高影响赤潮过程都发生在春末夏初的赤潮高发期,持续时间在10天以上;(2)赤潮爆发前期,伴随有暖湿气流影响形成适度降水,渤海西部的周平均海表温度(SST)升温明显,且SST≥16.2℃,赤潮发生海域为SST的暖脊控制,对赤潮过程的潜势预报有明显的指示意义;(3)850 h Pa以下层次的温度迅速上升,近地层西南暖湿气流的加强和地面6 m/s以下偏南、东南气流在渤海西部海域的汇合,利于渤海西部海洋浮游生物积聚和突发性繁殖,是赤潮形成的重要气象因子特征。  相似文献   

THE LOW-PRESSURE SYSTEM IN THE VERTICAL VELOCITY OMEGA ON THE SCALE OF SYSTEM SENSITIVITY     

曲维政  范婷婷  杜凌 《热带气象学报(英文版)》2015,21(S1):66-72

In this study, the relationship between scale and vertical velocity in a low-pressure system is explored using the wave characteristics of atmospheric disturbances and the structural characteristics of low-pressure systems. The ω differential equation, as determined by the transient geopotential height field Φ, is solved to obtain an analytical solution composed only of wavelength, horizontal speed, and atmospheric stability, i.e., the ω diagnostic equation of a low-pressure system. This equation also shows that vertical velocity in the low-pressure system is very sensitive to the horizontal scale, i.e., a smaller horizontal scale means a larger vertical velocity.  相似文献   

柴达木盆地区域性中到大雨个例分析   总被引：2，自引：0，他引：2  

张增文  苟日多杰  王发科  罗显发  郭晓宁 《气象科技》2007,35(1):88-91

应用平均场资料,对2005年7月7~10日柴达木盆地东部出现的区域性中到大雨天气过程进行了综合分析。结果表明:此次区域性中到大雨过程的发生与巴尔喀什湖低槽不断分裂的小槽、柴达木盆地对流层中低层的低涡(切变)和副高外围强盛发展的西南暖湿气流的共同作用密切相关。对流层中低层辐合、高层辐散和高湿度区的维持,以及强散度柱、强涡度柱耦合和高低空急流的稳定维持是产生这次区域性中到大雨天气过程的主要原因。  相似文献   

南祁连山前区中生代晚期古构造特征的研究     

肖安成  汪立群杨树锋  马立协沈中延  王亮  吴磊  陈元忠 《地质科学》2010,45(1):146-156

南祁连山前区可以分为露头和盆地区两个不同的大地构造单元,本区晚中生代构造活动强烈,控制了新生代的沉积过程和现今中生界残余层序的分布。本文提出了均匀平板状沉积体后期的构造变形可以利用古地质图以及高精度残余地层厚度的变化规律判断古构造带的分析方法,并且对于研究区中生代晚期的古构造特征进行了分析。露头区主要利用古地质图分析方法,研究区集中在赛什腾山-埃姆尼克山北缘的鱼卡和红山地区。盆地区主要利用中生界残余厚度图的分析方法,研究区集中在赛什腾山-埃姆尼克山南侧的赛什腾南部凹陷和马海凸起地区。通过这4个地区古构造特征的研究,提出南祁连山前区中生代晚期在区域性隆升的背景下,形成了一系列古构造带,古构造活动的特点是形成北西-北北西走向的背斜和向斜构造,这些褶皱的波长为15～20 km,为中尺度规模。同时指出,中国西部多数地区均缺失上白垩统,暗示着当时的中亚地区存在一个广阔的晚白垩世古高原。  相似文献