鄂尔多斯盆地早白垩世构造热事件形成动力学背景及其对油气等多种矿产成藏（矿）期的控制作用   总被引：1，自引：1，他引：1  

任战利  祁凯  刘润川  崔军平  陈志鹏  张圆圆  杨桂林  马骞 《岩石学报》2020,36(4):1213-1234

华北克拉通中西部中生代晚期早白垩世是否存在岩石圈减薄是地学界普遍关注的重大地质问题。本文在作者多年来对鄂尔多斯盆地构造热演化史研究的基础上,充分收集了近年来前人研究的成果及进展,对鄂尔多斯盆地现今地温场、地壳结构、构造热事件、深部热岩石圈厚度、早白垩世火成岩活动期次、构造热事件形成机理及构造热事件与多种矿产成藏成矿关系方面进行探讨。鄂尔多斯盆地现今地温梯度及大地热流中等,属中温型盆地,现今地温场受现今地壳、岩石圈厚度较厚控制。通过对构造背景、古地温恢复、火成岩活动及热岩石圈厚度恢复等资料分析发现早白垩世太行山以西的山西地块及鄂尔多斯盆地处于拉张背景,早白垩世地温梯度高,存在古地温异常及热事件。早白垩世鄂尔多斯盆地热岩石圈厚度明显较现今岩石圈厚度薄,表明华北克拉通中生代晚期以来岩石圈减薄的西界可推到鄂尔多斯盆地。华北克拉通中西部鄂尔多斯盆地周缘、华北克拉通中部山西地块、华北克拉通中西部南缘早白垩世火成岩形成时间相同,岩浆侵入和喷出的时代主要集中在138～108Ma,反映在燕山晚期早白垩世华北克拉通中西部存在一期较为强烈的热事件。火成岩地球化学分析表明火成岩来源为地幔,反映岩石圈处于拉张背景。早白垩世热事件发生的时间与华北克拉通岩石圈减薄的峰期年龄相一致,表明华北克拉通岩石圈减薄作用在华北克拉通中西部广泛存在。早白垩世构造热事件发生的根本原因在于鄂尔多斯盆地岩石圈深部热活动增强,深部软流圈物质上涌,岩石圈厚度减薄。通过对油气、煤、铀等金属矿产成矿(藏)时代与热事件的对应关系分析发现鄂尔多斯盆地油气、煤、铀矿产及华北克拉通中西部金属矿产的形成受控于早白垩世构造热事件及岩石圈拉张减薄的深部热背景,主要成藏(矿)期均为早白垩世,成藏、成矿具有爆发式及同时性特点。  相似文献   

House change detection based on DSM of aerial image in urban area   总被引：1，自引：1，他引：0  

FAN Hong ZHANG Jianqing ZHANG Zuxun LIU Zhifang FAN Hong  Associate Professor  National Laboratory for Information Engineering in Surveying  Mapping  Remote Sensing  WTUSM  Luoyu Road  Wuhan  China 《地球空间信息科学学报》1999,2(1):68-72

The change of house often brings on the change of DSM in an area over different periods. If we can apply information of the height of houses to reinforce the house change detection, the reliability and efficiency of detection methods will be improved greatly.From this viewpoint, a new approach taking advantage of both height data from an image pair and image data is proposed to detect the house change in urban area and is called "data fusion technology".  相似文献   

Development of a simple method for determining the influence radius of a pumping well in steady-state condition          下载免费PDF全文

A S El-Hames 《地下水科学与工程》2020,8(2):97-107

Influence radius of a pumping well is a crucial parameter for hydrogeologists and engineers. Knowing the radius of influence for a designed drawdown enables one to calculate the pumping rate required to layout a project foundation that may need lowering of groundwater level to a certain depth due to dewatering operation. In addition, this is important for hydrogeologists to determine ground water contamination flow paths and contributing recharge area for domestic water supply and aquifer management purposes. Empirical formulas that usually neglect vital parameters to determine the influence radius accurately have been traditionally utilized due to lack of adequate methods. In this study, a physically based method, which incorporates aquifer hydraulic gradient for determining the influence radius of a pumping well in steady-state flow condition, was developed. It utilizes Darcy and Dupuit laws to calculate the influence radius, where Darcy's law and Dupuit equation, in steady-state condition, represent the inflow and the outflow of the pumping well, respectively. In an untraditional manner, this method can be also used to determine aquifer hydraulic conductivity as an alternative to other pumping test methods with high degree of accuracy. The developed method is easy to use; where a simple mathematical calculator may be used to calculate the influence radius and the pumping rate or hydraulic conductivity. By comparing the results from this method with the MODFLOW numerical model outputs with different simulated scenarios, it is realized that this method is much superior and more advantageous than other commonly used empirical methods.  相似文献   

新型太阳池的研究   总被引：3，自引：0，他引：3       下载免费PDF全文

罗莎莎  郑绵平 《盐湖研究》2003,11(3):65-70

盐梯度太阳池是运用最广泛的太阳能收集系统之一 ,但是在运行过程中存在许多不足 ,人们相继开展了新型太阳池的研究 ,针对这些新型太阳池进行了概述 ,并比较了它们的优缺点  相似文献   

地球磁层顶磁场重联的动力学过程          下载免费PDF全文

曹晋滨  马志伟  路立  周国成  刘振兴 《地球物理学报》2002,45(5):597-604

用三维可压缩MHD数值模拟研究了在磁场重联过程中电子压力梯度项的效应研究结果发现在较高等离子体β,较小离子惯性尺度条件下,广义欧姆定理中压力梯度项在重联过程的作用不可忽略.在磁重联过程中,压力梯度项虽然没有明显改变磁场拓扑结构和重联速度,但它使电子和离子速度明显增大.由于在离子惯性尺度下,离子和电子运动解耦,电子是电流的主要载流子,所以场向电流也增大,并导致核心磁场明显增大.考虑到场向电流是磁层电离层耦合的一个重要因素,所以电子压力梯度项的引入加强了行星际磁场南向期间磁层电离层的耦合.电子压力梯度项还在重联区激发了波动,该波动可向重联区外传播.  相似文献   

南半球气候锋的统计特征分析          下载免费PDF全文

何宏让  史卫  章立标  董刚  章东华 《气象科学》2002,22(2):175-182

本文利用 1995 - 97年 NCEP全球 2 .5°× 2 .5°经纬网格点再分析资料对南半球的温度梯度和厚度梯度的分布特征进行了分析 ,给出了南半球副热带洋面上锋面的产生与厚度、温度梯度的关系 ,从而得出南半球气候锋活动规律、发生源地及其基本特征 ,并概括出南半球气候锋存在的依据  相似文献   

贺兰山地区沙尘暴沙尘起动和垂直输送物理因子的综合研究   总被引：37，自引：2，他引：37  

牛生杰  章澄昌 《气象学报》2002,60(2):194-204

根据 4a来在贺兰山两侧沙漠和沙地测站积累的微气象和沙尘谱观测资料 ,结合有关文献 ,综合分析了沙尘起动和垂直输送的物理机制 ;讨论了强风的动力作用、近地面不稳定层结的热力作用和沙尘物质源特征 ;概述了不同尺度天气系统中上升运动特征 ,沙尘的沉降末速计算、沙漠地表的湍流输送特征和垂直速度资料、沙漠地表的超绝热梯度出现的频率和强度及逆湿现象 ,沙漠和沙地的沙尘粒度、地表性质和沙土含水率对起动风速的影响。  相似文献   

THE FORMATION MECHANISM OF CONCENTRIC DOUBLE EYE WALL TYPHOON—PART Ⅰ: DYNAMICAL ANALYSIS^*          下载免费PDF全文

PENG Jiayi  FANG Juan  WU Rongsheng 《Acta Meteorologica Sinica》2004,18(3):301-312

The strong vortex will mutually adjust the thermodynamic field and dynamic field to a state of gradient balance whilst forced by an external cold source,namely,the gradient adjustment process,in which a linearized two-layer model is dealt with in this paper.The analyses show that on account of the heterogeneous radial distribution of the cold source,the adjustment of the thermodynamic and dynamic fields results in the two-peak tangential wind feature,which is analogous to the character of concentric double eyewalls in the strong typhoon.Consequently,the gradient adjustment may be one possible mechanism for the formation of a concentric double-eye typhoon.  相似文献   

Detection and Evaluation of Gas Hydrates in the Eastern Nankai Trough by Geochemical and Geophysical Methods   总被引：2，自引：0，他引：2  

Ryo Matsumoto    Hitoshi Tomaru  Hailong Lu 《Resource Geology》2004,54(1):53-67

Abstract: Interstitial waters extracted from the sediment cores from the exploration wells, “BH‐1” and “MITI Nankai Trough”, drilled ～60 km off Omaezaki Peninsula in the eastern Nankai Trough, were analyzed for the chloride and sulfate concentrations to examine the depth profiles and occurrence of subsurface gas hydrates. Cored intervals from the seafloor to 310 mbsf were divided into Unit 1 (～70 mbsf, predominated by mud), Unit 2 (70–150 mbsf, mud with thin ash beds), Unit 3 (150–250+ mbsf, mud with thin ash and sand), and Unit 4 (275–310 mbsf, predominated by mud). The baseline level for Cl “concentrations was 540 mM, whereas low chloride anomalies (103 to 223 mM) were identified at around 207 mbsf (zone A), 234–240 mbsf (zone B), and 258–265 mbsf (zone C) in Unit 3. Gas hydrate saturation (Sh %) of sediment pores was calculated to be 60 % (zone A) to 80 % (zones B and C) in sands whereas only a few percent in clay and silt. The total amount of gas hydrates in hydrate‐bearing sands was estimated to be 8 to 10 m³ of solid gas hydrate per m², or 1.48 km³ CH₄ per 1 km². High saturation zones (A, B and C) were consistent with anomaly zones recognized in sonic and resistivity logs. 2D and high‐resolution seismic studies revealed two BSRs in the study area. Strong BSRs (BSR‐1) at ～263 mbsf were correlated to the boundary between gas hydrate‐bearing sands (zone C) and the shallower low velocity zone, while the lower BSRs (BSR‐2) at～289 mbsf corresponded to the top of the deeper low velocity zone of the sonic log. Tectonic uplift of the study area is thought to have caused the upward migration of BGHS. That is, BSR‐1 corresponds to the new BGHS and BSR‐2 to the old BGHS. Relic gas hydrates and free gas may survive in the interval between BSR‐1 and BSR‐2, and below BSR‐2, respectively. Direct measurements of the formation temperature for the top 170 m interval yield a geothermal gradient of ～4.3d?C/ 100 m. Extrapolation of this gradient down to the base of gas hydrate stability yields a theoretical BGHS at～230 mbsf, surprisingly ～35 m shallower than the base of gas hydrate‐bearing sands (zone C) and BSR‐1. As with the double BSRs, another tectonic uplift may explain the BGHS at unreasonably shallow depths. Alternatively, linear extrapolation of the geothermal gradient down to the hydrate‐bearing zones may not be appropriate if the gradient changes below the depths that were measured. Recognition of double BSRs (263 and 289 mbsf) and probable new BGHS (～230 mbsf) in the exploration wells implies that the BGHS has gradually migrated upward. Tectonically induced processes are thought to have enhanced dense and massive accumulation of gas hydrate deposits through effective methane recycling and condensation. To test the hypothetical models for the accumulation of gas hydrates in Nankai accretionary prism, we strongly propose to measure the equilibrium temperatures for the entire depth range down to the free gas zone below predicted BGHS and to reconstruct the water depths and uplift history of hydrate‐bearing area.  相似文献   

Mechanical stratigraphy as a factor controlling the development of a sandbox transfer zone: a three-dimensional analysis   总被引：3，自引：0，他引：3  

Antonio Ravaglia  Claudio Turrini  Silvio Seno 《Journal of Structural Geology》2004,26(12):2269-2283

In thrust belts, fold–fault terminations are common features of the structural architecture and can pose complicated problems to unravel, in particular when two or more terminations are in close proximity. Such terminations usually reflect pre-existing attributes. Amongst the many factors, lateral variations in the mechanical stratigraphy can control along-strike geometry and kinematics of fault-related folds.A displacement transfer zone was produced in a compressional sandbox model by means of two adjacent, mechanically different stratigraphic domains. The experiment allowed two discrete chains to develop in the different domains, so that a complex structural setting occurred in the connecting area. Periclinal folds, oblique thrust fronts and oblique ramps developed in the resulting transfer zone. The interaction between periclines in the transfer zone produced lateral culminations in the folded structures. The analysis of displacement across the structural domains revealed that a significant loss of slip along the faults occurred in the relay zone. In this area, imbricate faulting was partially replaced by layer-parallel shortening. A linear relationship appears to exist between the bed length of the thrust sheet and the related fault slip.  相似文献