黄铁矿型结构的晶体化学

本文根据特征离子坐标变化的特点，对黄铁矿型结构微变规律性进行了讨论，作了一些规律图，总结出：成分的变化控制着ｕ值的变化，ｕ值的变化影响着晶体结构微变化。ｕ值发生变化，ＭＸ６反三方柱的顶面和底面中３轴相向或相背移动，ｕ值增加愈接近正八面体，ｕ值发生变化，Ｘ（Ｍ３Ｘ）三方锥底面的方位不变，但锥顶（Ｘ７）和锥体内的（Ｘ１）的坐标要变化，它们会沿着锥的中轴线相向或相背移动，形成扁平型的三方锥，最后得出：当     

Pile driving by numerical cavity expansion

A cavity expansion procedure for the simulation of pile driving is presented and assessed in this paper. The analysis uses a non-linear finite-element model and the penetration of the pile into the soil is simulated by a radial opening of the soil around the pile. The case of a pile advanced by expansion will be compared to a similar pile subjected to computational driving (referred to, respectively, as ‘expanded’ and ‘driven’ piles for convenience). The state of stress and deformation, and the evolution of pore-water pressure in the soil will be monitored for the expanded and driven piles. Further computational driving will be applied to both cases and the pile response and soil resistance will be compared. The computational cost of advancing the pile by expansion will finally be investigated. Copyright © John Wiley & Sons, Ltd.     

新CT技术在恐龙蛋化石扫描中的应用与发现

恐龙蛋化石是探索恐龙起源和演化的重要研究材料, 由于恐龙蛋化石的珍贵性, 对其进行实体解剖的可行性较小, 应用医学界CT扫描技术于恐龙蛋化石的内部形态研究具有特别的意义。早期部分学者已应用CT扫描对恐龙蛋化石进行了有益尝试, 绝大多数均显示恐龙蛋化石内的胚胎结构由于成岩作用未被保存下来, 仅有少数报道保存了恐龙蛋胚胎结构, 但也因当时CT扫描技术不完善, 结果不明确、图像不清晰等可能存在着一定问题。本次研究利用第二代双源CT(SOMATOM Definition Flash CT)以1 mm层厚, 1 mm间距对长安大学地质博物馆馆藏18枚恐龙蛋化石内部结构进行研究, 测出恐龙蛋内部各部分的密度分布数据, 发现仅有一枚标本卵壳与原生质之间存在规则的空腔, 可能保存了恐龙蛋胚胎的原始结构。     

同位素填图与深部物质探测(Ⅱ)：揭示地壳三维架构与区域成矿规律

地球深部是大规模成矿作用的“驱动机”、“供应源”和“传输带”。深入揭示深部物质组成与分布、物质循环与能量转换、三维架构与动力过程,对理解成矿作用至关重要。岩浆岩“探针”及区域同位素(如全岩Nd、锆石Hf)填图是探索深部物质组成与演化过程的主要手段,可以探测地壳深部物质组成的三维架构,揭示新生地壳/古老地壳/再造地壳的空间分布与时空演变,从而为提升区域成矿规律认识提供深部物质制约证据,有助于成矿潜力的定量半定量评价及其区域成矿预测。文章重点总结和探讨了岩浆岩全岩Nd同位素和锆石Hf同位素区域填图在解决地壳三维架构与成矿规律方面的应用成果,深入探讨了巨量岩浆岩发育的深部驱动机制及其成矿制约,对比总结了不同类型造山带(如中亚增生造山带、青藏高原碰撞造山带、秦岭复合造山带等)和不同克拉通的地壳深部组成结构与成矿制约特色。研究显示：不论是什么造山带和克拉通,深部年轻地壳分布区制约了铜金、铜镍等矿床的形成分布;古老地壳控制了大型钼矿、铅锌矿、稀有金属等矿产;两者过渡地带常常发育铁矿等。这些研究不仅揭示了区域成矿规律,而且对成矿预测与成矿潜力评价有潜在的应用价值,有可能成为成矿规律研究特别是深部物质探测及成矿背景研究的新方向。     

东安牛头寨地区锑矿床控制因素及成因探讨

锑矿床严格受构造控制，表现出逐级控矿特征：区域性F1断裂、牛头寨复式背斜及北北东、北北西、北西向次级断裂，分别控制着锑矿带、锑矿床的空间展布及锑矿脉的形态、产状与规模。地层岩石建造对成矿的控制，主要表现在赋矿地层中的白云岩、硅质岩等易碎裂，为矿液的运移提供了有利的通道。部分含矿地层的Sb高丰度，还可能成为矿提供了矿源。已有的研究表明，锑矿床的硫同位素组成具有岩浆硫特征，并混入了部分围岩沉积硫。石英的氢氧同位素组成反映出岩浆流体与变质水混入溶液特征。矿物包裹体的爆裂温度平均为157℃。石英的包裹体成分测试结果，揭示了矿液为K－Na-Ca-Cl型富硅的弱碱性溶液。矿床成因厘定为岩浆期后中低温热液脉状充填矿床。     

SOURCE RADIATION AND RESPONSES OF WAVE PROPAGATION

Recordings of seismic waves propagating from earthquake source to a station at the earth's surface are a system response function.The convolution operator in time domain can be simplified as a multiplication operator in frequency domain.We discuss in frequency domain the separation of source,path and site effects for global scaling of earthquake source radiation.Also discussed are source scaling model,faulting mechanism,and the H/V inversion problems with crustal and near surface structures.Gross features of apparent source spectra appear to be not much region-dependent although there may be difference between tectonic styles within a region of tectonic mixture for which we need further study as data accumulate.Vertical spectra may be a better approach to approximate source radiation,as it has less crustal amplification effects than horizontal spectra.The H/V ratio is evidently a comprehensive indicator of amplification effects from near surface to deep structure.This gives it potential as an inversion tool to deduce site crustal structure.     

复杂岩性储层渗透率-应力敏感性及其对气井产能的影响

采用变流压定围压试验方式,在高温、高压条件下模拟了气藏开发过程,研究了复杂火山岩气藏储层渗透率应力敏感性,对比了变流压定围压与常规的定流压变围压方式评价储层应力敏感性的异同。试验结果表明,火山岩储层渗透率随着孔隙压力的减小而减小,渗透率减小主要发生在孔隙压力从40 MPa下降至25 MPa的变化区间,渗透率损失率与其初始渗透率之间的相关性较差,这与常规沉积砂岩储层具有一定的差别。变流压定围压试验评价的应力敏感性强于定流压变围压评价结果,气藏储层有效应力变化范围内两种试验评价的应力敏感性结果差异更大。基于渗流力学理论,推导得到考虑应力敏感性的气井产能方程。计算结果表明,考虑应力敏感性时气井无阻流量约为不考虑应力敏感性时的63.28%,应力敏感性对气井产能的影响随着生产压差的增大而增大。     

Use of sparse iterative methods for the resolution of three-dimensional soil/structure interaction problems

In this paper we present a study of the performance of sparse iterative solvers regarding the resolution of three-dimensional and non-linear problems encountered in soil/structure interaction. It is composed of two parts. In the first one, we present briefly iterative methods and preconditioners used in this study, then we analyse their performance on three soil/structure interaction problems: a shallow foundation under a vertical loading, a single pile subjected to a lateral loading and the construction of a lined tunnel in a soft soil. Tests are performed assuming an elastic–perfectly plastic constitutive law for the soil material with a non-associated Mohr–Coulomb flow rule. Copyright © 1999 John Wiley & Sons, Ltd.     

Geology and geochemistry of fault-hosted hydrothermal and sedimentary manganese deposits in the Oakover Basin,east Pilbara,Western Australia

Manganese mineralisation in the Oakover Basin is associated with Mesoproterozoic extension, basin formation and deposition of the Manganese Group. The underlying basement architecture of the Oakover Basin (a local half-graben geometry), inherited from the Neoarchean rifting event, plays an important role on the distribution, style and timing of manganese deposits. Fault-hosted manganese deposits are dominant along the ‘active’ faulted eastern margin, whereas flat-lying sedimentary deposits are dominant along the western ‘passive’ margin reflecting differences in ore-forming processes. The large number of significant manganese deposits in the Oakover Basin, previously thought to reflect a spatial association with Carawine Dolomite, more likely reflects the restricted nature of the Mesoproterozoic basin and development of a large reservoir of Mn²⁺ and Fe²⁺ in an anoxic zone of a stratified basin. Low O₂ conditions in the basin were caused by a paleotopographic high forming a barrier to open ocean circulation. The western margin sedimentary deposits formed later than the fault-hosted hydrothermal deposits along the eastern margin, once a significant reservoir of Mn²⁺ and Fe²⁺ had developed, and when there was sufficient subsidence to allow migration of the redox front onto the shallow shelf, with Mn precipitation on and within the seafloor sediments. The sedimentary manganese deposits are not uniformly distributed along the western edge of the basin; instead they are concentrated into discrete areas (e.g. Mt Cooke–Utah–Mt Rove, Bee Hill, Skull Springs and the Ripon Hills districts), suggesting a degree of structural control on their distribution. Fault-hosted manganese is observed beneath and adjacent to many of the sedimentary deposits. Marked geochemical differences are observed between the Woodie Woodie hydrothermal deposits and the sedimentary deposits. Woodie Woodie deposits display higher Ba, U, Mo, As, Sn, Bi, Pb, S and Cu than the sedimentary deposits, reflecting the composition of the hydrothermal fluids. The Al₂O₃ values of the Ripon Hills and Mt Cooke deposits are much higher than the Woodie Woodie deposits, reflecting the composition of the dominant host rock, as Al₂O₃ is typically <5 wt% in the Carawine Dolomite, but is >10 wt% in basal shale units of the Manganese Group. Highly variable Mn:Fe ratios (?5:1) in the hydrothermal manganese at Woodie Woodie reflects rapid deposition of Mn in and around fault zones. In contrast, slower accumulation of Mn oxides on and within the seafloor to form the large sedimentary deposits results in Mn:Fe ratios closer to 1:1 and elevated Co + Ni and REE values.     

Centralized power and divided space: `Fractured regions' in the Israeli `ethnocracy'

This paper uses a critical political-geographical perspective to account for the high centrality of power found in Israel. It suggests that the concentration of power have not been solely caused by national solidarity and integration or by metropolitan development, as commonly explained, but also by the territorial `fracturing' of the main social and ethnic groups in Israel/Palestine. This has prevented the emergence of effective pressure for regional devolution. Israel's character as a settler and settling state, and its central project of Judaizing contested territories, enabled the Israeli `ethnocracy' and its (mainly Ashkenazi and secular) elites to create a political geography of `fractured ethnic and social regions'. Dispersing minorities and legitimizing segregation and inequality, all in the name of the `national interest', achieved this. The Israeli political landscape is therefore organized as `fractured regions', each representing a distinct and interconnected, yet geographically dispersed, set of localities, and resembling a `chain of beads'. The logic of dispersal and segregation, in turn, has also influenced patterns of development and residential separation within Israel's main urban areas. Thus, ethnic and social fragmentation and conflict, and not a putative process of national or metropolitan integration, can explain much of Israel's highly centralized power structure.