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131.
132.
内蒙古东部闹牛山铜矿成矿地质背景分析 总被引:4,自引:0,他引:4
通过对闹牛山铜矿区与成矿有关的次火山岩岩石化学分析,以及对矿区火山一次火山岩微量元素、稀土元素的分析,结合相关的铅同位素分析,综合分析了该矿床的成矿地质背景。认为:闹牛山铜矿床构造环境属于大陆边缘裂陷带的局部隆起区,成矿火山岩浆为钙碱性,其来源于地壳深部或上地慢,并有上部地壳物质混染。 相似文献
133.
湘中南二叠系孤峰组硅质岩的成因属性及其地球动力学指示意义 总被引:5,自引:0,他引:5
华南二叠系底部的硅质岩及同一层位对应于华南重要的地幔强活动期和成矿期,有非常重要的动力学指示意义。研究表明,孤峰组剖面的岩性可划分为三段:泥页岩段、厚层状硅质岩段和薄层状硅质岩段。沿剖面自下而上,Al2O3、K2O和TiO2含量逐渐降低,MnO、TFe等组分逐渐升高;稀土元素显示出一定的铈负异常,∑REE偏低,且向上∑REE逐渐减少而HREE/LREE逐渐增高;一些热水沉积诊断性微量元素如As、Sb、Hg等也显示出一定程度的异常。这些特征均表明硅质岩的成岩过程中包含有正常沉积和热水沉积的共同作用,且自下而上热水沉积作用逐渐增强的趋势。这种成岩作用的演化特征,代表了下扬子地台拉张裂陷盆地对晚古生代伸展背景的沉积响应,对于探讨裂谷盆地阶段性发育的动力学特征有一定的指示意义。 相似文献
134.
Abstract Spatial and temporal variations in radiative fluxes influence glacier mass‐balance in mountain areas. The primary goal of this study was to assess differences in solar radiation on three glacial cirques located in the Maladeta Mountain massif (Central Spanish Pyrenees), and analyse their implications on glacier development and morphology. A quantitative approach is adopted to obtain the values of solar radiation (direct, diffuse and global radiation), combining several field data parameters (measured at 55 control‐points) with the solar radiation modelling package Ecosim. The data obtained confirm that the morphologies of the glacial bodies developed in the three cirques have a good correlation with the spatial variation on solar radiation inputs, favouring also the conservation (Aneto and Coronas cirques) or total vanishing (Llosás cirque) of the glacial remnants analysed here. The study shows how strongly in this Alpine‐Mediterranean context solar radiation — firstly as a function of latitude and time of year, and locally as a function of topographic slope, aspect and shadowing — controls the mass‐balance and the spatial distribution of melting in small glaciers, having an effect on the development of their morphologies. 相似文献
135.
136.
A new efficient method is developed for the analysis of pile-group effects on the seismic stiffness and strength design of buildings with pile foundations. An efficient continuum model consisting of a dynamic Winkler-type soil element and a pile is used to express the dynamic behavior of the structure-pile-soil system with only a small numerical error. The pile-group effect is taken into account through the influence coefficients among piles which are defined for interstory drifts and pile-head bending moments. It is shown that, while the pile-group effect reduces the interstory drift of buildings in general, it may increase the bending moment of piles at the head. This means that the treatment without the pile-group effect results in the conservative design for super-structures and requires a revised member design for piles. 相似文献
137.
Timing and amount of solar radiation were examined as factors influencing the distribution of seven perennial plants on a small mountain located in the Chihuahuan Desert. Average direct beam solar radiation fluxes at differing times throughout the day and year were estimated with computer calculations. Principal components analysis was used to reduce the number of solar radiation parameters and include the maximum available information with a manageable number of variables. The remaining solar radiation parameters were compared to plant distributions using redundancy analysis and generalized additive models. Unimodal, bimodal, and monotonic responses were all found depending upon the species and solar radiation parameter. Niche separation at this location depends upon the timing as well as the amount of solar radiation. 相似文献
138.
根据中国东部各省(区、市)区域地质志、1∶50万地质图和中国东部地壳与岩石元素丰度研究成果首次编制的中国东部60种元素的岩石地球化学图,基本反映了与特定岩性有关的区域岩石地球化学元素含量分布特征和与大地构造单元有关的区域地球化学元素含量分布特征,直观表达了中国东部空间地理上元素背景含量的宏观分布与变化,以及不同大地构造单元元素背景含量的变化趋势。这一成果为勘查地球化学、环境地球化学,特别是区域化探扫面水系沉积物资料的定量解释提供了基本依据,为基础地质、大地构造、区域成矿研究提供了重要资料,也为地球化学块体理论及其形成机制的研究提供了强有力的支持。 相似文献
139.
M. Koch-Müller P. Dera Y. Fei H. Hellwig Z. Liu J. Van Orman R. Wirth 《Physics and Chemistry of Minerals》2005,32(5-6):349-361
We synthesized superhydrous phase B (shy-B) at 22 GPa and two different temperatures: 1200°C (LT) and 1400°C (HT) using a
multi-anvil apparatus. The samples were investigated by transmission electron microscopy (TEM), single crystal X-ray diffraction,
Raman and IR spectroscopy. The IR spectra were collected on polycrystalline thin-films and single crystals using synchrotron
radiation, as well as a conventional IR source at ambient conditions and in situ at various pressures (up to 15 GPa) and temperatures
(down to −180°C). Our studies show that shy-B exists in two polymorphic forms. As expected from crystal chemistry, the LT
polymorph crystallizes in a lower symmetry space group (Pnn2), whereas the HT polymorph assumes a higher symmetry space group (Pnnm). TEM shows that both modifications consist of nearly perfect crystals with almost no lattice defects or inclusions of additional
phases. IR spectra taken on polycrystalline thin films exhibit just one symmetric OH band and 29 lattice modes for the HT
polymorph in contrast to two intense but asymmetric OH stretching bands and at least 48 lattice modes for the LT sample. The
IR spectra differ not only in the number of bands, but also in the response of the bands to changes in pressure. The pressure
derivatives for the IR bands are higher for the HT polymorph indicating that the high symmetry form is more compressible than
the low symmetry form. Polarized, low-temperature single-crystal IR spectra indicate that in the LT-polymorph extensive ordering
occurs not only at the Mg sites but also at the hydrogen sites. 相似文献
140.
Three dimensional numerical simulation of residential building on shrink–swell soils in response to climatic conditions 下载免费PDF全文
Shrink–swell soils can cause distresses in buildings, and every year, the economic loss associated with this problem is huge. This paper presents a comprehensive system for simulating the soil–foundation–building system and its response to daily weather conditions. Weather data include rainfall, solar radiation, air temperature, relative humidity, and wind speed, all of which are readily available from a local weather station or the Internet. These data are used to determine simulation flux boundary conditions. Different methods are proposed to simulate different boundary conditions: bare soil, trees, and vegetation. A coupled hydro‐mechanical stress analysis is used to simulate the volume change of shrink–swell soils due to both mechanical stress and water content variations. Coupled hydro‐mechanical stress‐jointed elements are used to simulate the interaction between the soil and the slab, and general shell elements are used to simulate structural behavior. All the models are combined into one finite element program to predict the entire system's behavior. This paper first described the theory for the simulations. A site in Arlington, Texas, is then selected to demonstrate the application of the proposed system. Simulation results are shown, and a comparison between measured and predicted movements for four footings in Arlington, Texas, over a 2‐year period is presented. Finally, a three‐dimensional simulation is made for a virtual residential building on shrink–swell soils to identify the influence of various factors. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献