湖北省铜山口铜(钼)矿床成矿流体水岩反应数值模拟

湖北省铜山口铜(钼)矿床是一典型的夕卡岩 斑岩复合型矿床。通过对其流体包裹体的系统研究,确定了成矿流体的成分及温压条件;结合矿床学的研究,将成矿过程分解为两个平行的成矿阶段,即夕卡岩型矿化阶段和斑岩型矿化阶段。根据Johnson和Reed等人建立的水 岩反应模型,对该矿床的成矿流体与围岩的反应并析出金属沉淀的过程进行了数值模拟计算。结果表明:在斑岩型矿化阶段,成矿流体系统出现等焓减压沸腾过程并沉淀出大量的金属矿物,成矿流体分异为低盐度流体和高盐度流体;在夕卡岩型成矿阶段,沉淀出典型的夕卡岩矿物;在整个成矿过程中,成矿流体的pH值逐渐升高。模拟计算结果与实际地质现象非常吻合,说明所建立的水 岩反应模型可以为理解这一类复合型金属热液矿床的形成机制提供一个新的思路。     

Evaluation of distributed recharge in an upland semi-arid karst system: the West Bank Mountain Aquifer,Middle East

Assessment of recharge in a structurally complex upland karst limestone aquifer situated in a semi-arid environment is difficult. Resort to surrogate indicators such as measurement of spring outflow and borehole discharge, is a common alternative, and attempts to apply conventional soil moisture deficit analysis may not adequately account for the intermittent spate conditions that arise in such environments. A modelling approach has been made using the West Bank Mountain Aquifer system in the Middle East as a trial. The model uses object oriented software which allows various objects to be switched on and off. Each of the main recharge processes identified in the West Bank is incorporated. The model allows either conventional soil moisture deficit analysis calculations or wetting threshold calculations to be made as appropriate, and accommodates both direct recharge and secondary recharge. Daily time steps enable recharge and runoff routing to be calculated for each node. Model runs have enabled a series of simulations for each of the three aquifer basins in the West Bank and for the whole of the West Bank. These provide recharge estimates comparable to those prepared by earlier workers by conventional means. The model is adaptable and has been successfully used in other environments.     

FLAC数值模拟软件及其在地学中的应用

FLAC是以拉格朗日差分法为基础的一种数值模拟应用软件,主要用于岩土力学工程。近年地质学家将其应用到地质构造和块体运动学、动力学研究中,以证实或证伪地球学家们提出的相关地球动力学模型。本文初步介绍了FLAC应用软件的基本原理、使用方法以及它在国内外地质学上的几个应用实例。     

上新世中期中国气候的数值模拟分析

使用中国科学院大气物理研究所的全球大气环流模式,曾就上新世中期(距今约3百万年前)气候进行过数值模拟试验,在已有针对全球气候进行分析的工作基础上,集中研究了该地质时期我国气候的变化特征。数值试验结果表明,除了青藏高原地区由于地形海拔高度变化而引起的局地冷却现象以外,上新世中期我国约100°E以东地区地表气温上升4～8℃,升温中心位于江淮流域下游地区; 该经度线以西地区地表气温升幅相对要弱一些,在1～4℃之间。上新世中期年均降水在我国东部地区显著减少,平均减幅在0.5mm/天以上,特别是在长江中游地区; 新疆北部、青海和西藏大部年均降水略有增加,而新疆中部和南部年均降水略有减少。在对流层低层,上新世中期东亚冬季风系统减弱,夏季风系统总体上略有减弱; 在对流层中层,冬季东亚大槽显著减弱,夏季中高纬度地区500hPa位势高度升高。在以上结果中,上新世中期我国气候相对于现在偏暖、东亚冬季风强度减弱得到了代用资料的支持。     

一种基于面模型的巷道三维自动建模方法研究

研究了一种基于面模型的矿山巷道三维自动建模方法。巷道建模分解为网络建模、断面建模、巷道段建模以及空间交汇几个步骤。对建模过程涉及的各算法进行了分析,基采用C++编程实现整个建模过程,并总结了有待进一步研究的问题。     

Historical tsunami in the Makran Subduction Zone off the southern coasts of Iran and Pakistan and results of numerical modeling

Tsunami hazard in the Makran Subduction Zone (MSZ), off the southern coasts of Iran and Pakistan, was studied by numerical modeling of historical tsunami in this region. Although the MSZ triggered the second deadliest tsunami in the Indian Ocean, among those known, the tsunami hazard in this region has yet to be analyzed in detail. This paper reports the results of a risk analysis using five scenario events based on the historic records, and identifies a seismic gap area in western Makran off the southern coast of Iran. This is a possible site for a future large earthquake and tsunami. In addition, we performed numerical modeling to explain some ambiguities in the historical reports. Based on the modeling results, we conclude that either the extreme run-up of 12–15 m assigned for the 1945 Makran tsunami in the historical record was produced by a submarine landslide triggered by the parent earthquake, or that these reports are exaggerated. The other possibility could be the generation of the huge run-up heights by large displacements on splay faults. The results of run-up modeling reveal that a large earthquake and tsunami in the MSZ is capable of producing considerable run-up heights in the far field. Therefore, it is possible that the MSZ was the source of the tsunami encountered by a Portuguese fleet in Dabhul in 1524.     

SELFE: A semi-implicit Eulerian–Lagrangian finite-element model for cross-scale ocean circulation

Unstructured-grid models grounded on semi-implicit, finite-volume, Eulerian–Lagrangian algorithms, such as UnTRIM and ELCIRC, have enjoyed considerable success recently in simulating 3D estuarine and coastal circulation. However, opportunities for improving the accuracy of this type of models were identified during extensive simulations of a tightly coupled estuary–plume–shelf system in the Columbia River system. Efforts to improve numerical accuracy resulted in SELFE, a new finite-element model for cross-scale ocean modeling. SELFE retains key benefits, including computational efficiency of existing semi-implicit Eulerian–Lagrangian finite-volume models, but relaxes restrictions on grids, uses higher-order shape functions for elevation, and enables superior flexibility in representing the bathymetry. Better representation of the bathymetry is enabled by a novel, “localized” vertical grid that resembles unstructured grids. At a particular horizontal location, SELFE uses either S coordinates or SZ coordinates, but the equations are consistently solved in Z space. SELFE also performs well relative to volume conservation and spurious oscillations, two problems that plague some finite-element models. This paper introduces SELFE as an open-source code available for community use and enhancement. The main focus here is on describing the formulation of the model and on showing results for a range of progressively demanding benchmark tests. While leaving details to separate publications, we also briefly illustrate the superior performance of SELFE over ELCIRC in a field application to the Columbia River estuary and plume.     

A control-volume finite-element method for three-dimensional multiphase basin modeling

In this paper we describe a 3D control-volume finite-element method to solve numerically the coupled partial differential equations (PDEs) governing geological processes involved in the evolution of sedimentary basins. These processes include sediment deposition and deformation, hydrocarbon generation, multiphase fluid flow, and heat transfer in deforming porous media.     

苏皖下扬子区晚白垩世以来的构造-热历史：浦口组砂岩磷灰石裂变径迹证据

对苏皖下扬子区上白垩统浦口组（K2P）的三个砂岩样品进行了磷灰石裂变径迹（AFT）研究。结果显示：2个样品的AFT合并年龄为（88．8±4．4）Ma（径迹长度为（12．0±0．3）μm）和（82．1±6．8）Ma（径迹长度为（14．4±0．3）μm）与浦口组沉积年龄相近,说明它们沉降的幅度达到但没有超过AFT部分退火区间,1个样品的AFT合并年龄（117．3±5．9）Ma（径迹长度为（13．3±0．3）μm）大于浦口组沉积年龄,代表物源区抬升、剥露的冷却年龄。根据热历史模拟结果,识别出黄桥事件（110～90Ma）、仪征事件（70～60Ma）和三垛事件（35～22Ma）三期重要的构造事件,并将下扬子区晚白垩世以来的盆地演化划分为四个阶段：110～70Ma断坳复合型伸展盆地、70～35Ma拉张断陷盆地、35～22Ma挤压抬升阶段和22Ma至今坳陷盆地。     

The Structure of A Turbulent Jet in A Crossflow-Effect of Jet-Crossflow Velocity

A comprehensive numerical study on the three-dimensional structure of a turbulent jet in crossflow is performed. The jet-to-crossflow velocity ratio (R) varies in the range of 2 - 16; both vertical jets and inclined jets without excess streamwise momentum are considered. The numerical results of the Standard two-equation k-ε model show that the turbulent structure can be broadly categorised according to the jet-to-crossflow velocity ratio. For strong to moderate jet discharges, i.e. R> 4, the jet is characterized by a longitudinal transition through a bent-over phase during which the jet becomes almost parallel with the main freestream, to a sectional vortex-pair flow with double concentration maxima; the computed flow details and scalar mixing characteristics can be described by self-similar relations beyond a dimensionless distance of around 20-60. The similarity coefficients are only weakly dependent on R. The cross-section scalar field is kidney-shaped and bifurcated, vvith distinct double concentr