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81.
Abstract: Two adjacent volcanogenic massive sulfide (VMS) deposits, the Main Malusok and the Malusok Southeast, are delineated within Barangay Tabayo, Siocon, Zamboanga del Norte, Mindanao, Philippines. These deposits comprise massive to semi-massive sulfide lenses representing the down-dip equivalent of oxidized gossans. The massive sulfides have a primary mineral assemblage of pyrite-chalcopyrite-sphalerite with significant amounts of supergene copper in the form of chal-cocite. Owing to structural and metamorphic overprinting combined with intense alteration, primary textures are generally obliterated. Rock types are classified according to dominant mineral assemblages whereas the main lithologic units comprising the Malusok volcanic package are divided based on the position of each unit relative to the mineralized zone. The main lithologic units are designated as the hanging wall, the host, and the footwall sequences. In correlating the stratigraphy of the Main Malusok zone with that of the Malusok Southeast zone, a chlorite/epidote-rich interval located at the base of the hanging wall sequence serves as a distinct stratigraphic marker from which all lithologies are referred to. Comparisons between the stratigraphy of the two areas show that massive to semi-massive sulfide lenses are confined within a single stratigraphic interval representing the favorable horizon for the entire Malusok area. However, differences exist relative to style of mineralization and configuration of the altered interval between the Main Malusok and the Malusok Southeast VMS deposits. Based on characteristics exhibited by each individual deposit, it is inferred that the Main Malusok VMS deposit overlies a feeder zone whereas the Malusok Southeast sulfide lenses represent satellite deposits and transported blocks. 相似文献
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83.
Claudio Chiaruttini Stefano Grimaz Enrico Priolo 《Soil Dynamics and Earthquake Engineering》1996,15(2):75
A two-dimensional elastic Chebyshev spectral element method (SPEM) is used to model the seismic wavefield within a massive structure and in its vicinity. We consider 2-D models where a linear elastic structure, with quadrangular cross-section, resting on an elastic homogeneous half-space, is impinged upon by the waves generated by a surface impulse at some distance. The scattering of Rayleigh waves and the response of the structure are extensively analysed in a parametric way, varying size, mechanical parameters and shape of the load. Some of the models considered are representative of embankments and earth dams. The simulation shows that some models resonate, storing part of the incoming energy. With realistic parameters, the lowest resonance frequency is due to pure shear deformation and is controlled by the shear velocity and height of the load. Flexural modes are excited only at higher frequencies. The acceleration at the top of the structure may be five/seven times higher than at the base, depending on the mass of the structure. The gradual release of trapped energy produces a ground roll lasting several seconds after the wave front has passed. The ground-roll amplitude depends on the sturcture's mass and can be as large as 30% of the peak acceleration. Outside resonance conditions, the ground motion is almost unaffected by the presence of the artefact; the horizontal motion on top of it is nearly twice the motion at ground level. Similar results should be expected when the incident field is an upcoming shear wave. A qualitative discussion shows that the presence of anelastic attenuation in the embankment does not significantly alter the preceding conclusions, unless it is of very low values (e.g. Q < 15).The modelling results that we discuss indicate that the soil-structure interaction may substantially alter the ‘free-field’ ground motion. From a practical point of view, the main conclusions are: (1) careful analysis is necessary when interpreting seismic records collected in the vicinity of large artefacts; (2) seismic hazard at a site may depend on the presence of man-made structures such as embankments, dams, tall and massive buildings. 相似文献
84.
笔者在该文中着重表达了3方面研究成果:在陈述清水沟-白柳沟地区成矿地质背景基础上,描述了已知工业矿床的基本特征,并将其类比为两类矿床,其一为Zn-Pb-Cu型小铁山式矿床,以展布于郭密寺北火山穹隆北东和南西两侧的下柳沟、弯阳河、下沟及郭密寺矿床为代表;其二为Cu(-Zn)型白银厂式矿床,以出露在黑河古火山穹隆北翼近核部的香子沟矿床为实例。成矿前期、成矿时期,以及成矿后期地质条件的分析与概括表明,该地区与白银厂地区在海相火山岩的成岩环境─—裂谷岛弧、火山岩组合──双峰式、古火山机构类型──古火山穹隆,以及成矿机制──海底热液对流循环成矿等诸多方面都具相似性,是寻找铜多金属硫化物矿床的良好地段。提出了该区此类矿床的综合成矿模式,相信它在本地区扩大寻找小铁山式矿床和突破性寻找白银厂式矿床中具有重要指导意义和实际操作意义. 相似文献
85.
Nans Addor Hong X. Do Camila Alvarez-Garreton Gemma Coxon Keirnan Fowler Pablo A. Mendoza 《水文科学杂志》2020,65(5):712-725
ABSTRACTLarge-sample hydrology (LSH) relies on data from large sets (tens to thousands) of catchments to go beyond individual case studies and derive robust conclusions on hydrological processes and models. Numerous LSH datasets have recently been released, covering a wide range of regions and relying on increasingly diverse data sources to characterize catchment behaviour. These datasets offer novel opportunities, yet they are also limited by their lack of comparability, uncertainty estimates and characterization of human impacts. This article (i) underscores the key role of LSH datasets in hydrological studies, (ii) provides a review of currently available LSH datasets, (iii) highlights current limitations of LSH datasets and (iv) proposes guidelines and coordinated actions to overcome these limitations. These guidelines and actions aim to standardize and automatize the creation of LSH datasets worldwide, and to enhance the reproducibility and comparability of hydrological studies. 相似文献
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87.
Interactions between surface and groundwater are a key component of the hydrologic budget on the watershed scale. Models that honor these interactions are commonly based on the conductance concept that presumes a distinct interface at the land surface, separating the surface from the subsurface domain. These types of models link the subsurface and surface domains via an exchange flux that depends upon the magnitude and direction of the hydraulic gradient across the interface and a proportionality constant (a measure of the hydraulic connectivity). Because experimental evidence of such a distinct interface is often lacking in field systems, there is a need for a more general coupled modeling approach. 相似文献
88.
波动方程叠前深度偏移在地震勘探成像处理方面起着不可替代的作用。随着高性能大规模并行计算机技术的发展,波动方程叠前深度偏移计算在地震勘探中的应用有了很大进步。在波动方程叠前深度偏移处理中,庞大的数据规模与海量计算对计算性能提出了很高的要求。曙光4000A超级计算机系统是我国目前峰值速度最快的商用超级计算机系统,无论是硬件平台建设还是应用软件的配置方面,都具有良好的应用性能。基于该系统设计的三维波动方程叠前深度偏移(炮域)PSDM软件,采用动态负载平衡并行计算模式,具有较高的计算效率,高度的可扩展性和可靠性。 相似文献
89.
自适应神经模糊推理系统(ANFIS)在水文模型综合中的应用 总被引:1,自引:0,他引:1
由于目前已有很多比较成熟的流域水文模型,因此我们可以选用几个流域水文模型进行并行运算,来同时模拟流域降雨—径流关系。在相同的降雨输入情况下,不同模型得到的模拟流量必然会有所不同,模型效率系数和模拟精度也会不同。因此,如何将不同模型的模拟结果进行综合以进一步提高流量模拟精度是一个关键问题。本文选用自适应神经模糊推理系统(ANFIS)作为水文模型综合平台,以牧马河流域为试验区域,对两个并行运算水文模型(三水源新安江模型和总径流响应模型)的结果进行综合处理,得到了更稳健的流量模拟结果,大大提高了模型效率和模拟精度。该方法值得在实践中借鉴。 相似文献
90.
介绍了分布式计算环境和网络地理信息系统的概念,探讨了分布式计算环境下网络地理信息系统的几种实现方法,最后对未来的分布式网络地理信息系统发展进行了展望。 相似文献