青藏高原东缘缅萨洼金矿成矿流体地质地球化学特征

缅萨洼金矿位于中国中轴构造带的中南段,青藏高原的东缘,赋存于金河-箐河断裂带次级断裂羊坪子韧性剪切带中本文根据对该矿床硫化物流体包裹体的氦氩同位素、硫化物的硫同位素以及与硫化物共生的石英的流体包裹体特征、成分以及氢氧同位素组成的测定,讨论了缅萨洼金矿的成矿流体来源及其矿床成因。结果显示,该矿床硫化物流体包裹体中的3He/4He变化较小,为0.69-0.82,显示了地幔流体参与成矿作用的可能性。而4He的含量变化范围较大,一般在2.19-10.62×10-6cm3STP/g(方铅矿除外)与3He/4He相比,40Ar/36Ar的比值则变化较小,一般为251-509。而硫化物的δ34S同位素变化范围在-1.8-2.2‰,平均值为0.5‰,说明硫的地幔来源。与硫化物共生的石英的流体包裹体的类型主要有富液相的盐水溶液包裹体、富气相的盐水溶液包裹体、三相CO2包裹体、纯液相CO2包裹体以及有机流体包裹体。成矿流体的氢氧同位素则显示成矿流体来源于岩浆水(或地幔流体)与大气降水的混合流体,本文认为,缅萨洼金矿的成矿流体为地幔流体与大气降水的混合流体,是渐新世印度大陆与亚洲大陆碰撞之后,该地区大规模走滑与剪切作用过程中,局部伸展作用的产物。     

新疆东昆仑木孜塔格蛇绿混杂岩中发现富Nb玄武岩

富Nb 玄武岩以相对高的TiO2 含量、低的LILE/HFSE和LREE/HFSE比值以及(La/Nb)MN＜2为特征,是岛弧环境的典型产物。首次报道发现于新疆东昆仑木孜塔格蛇绿混杂岩中的富Nb玄武岩,并分析了它们的典型地球化学特征和构造环境,表明了它们形成在岛弧环境。     

The Migif–Hafafit gneissic complex of the Egyptian Eastern Desert: fold interference patterns involving multiply deformed sheath folds

The Wadi Hafafit Complex (WHC) is an arcuate belt of orthogneisses, migmatites and other high-grade metamorphic rocks, which marks the boundary between the Central Eastern and the South Eastern Deserts of Egypt. In the WHC, gneissic meta-gabbro outlines macroscopic fold interference patterns characterized by elliptical to irregular culminations cored by gneissic meta-tonalite to meta-trondhjemite. The five main culminations of the WHC have previously been labeled A (most northerly), B, C, D and E (most southerly). A detailed structural investigation of B, C, D and E reveals that these structures are a result of the interference of four macroscopic fold phases, the first three of which may represent a single deformation event. The first folding involved sheath-like fold nappes, which were transported to the N or NW, assisted by translation on gently dipping mylonite zones. The regional gneissosity and mineral extension lineations formed during this folding event. The fold nappes were deformed by mainly open upright small macroscopic and mesocopic folds with approximately NE-trending hinges. As a probable continuation of the latter folding, the sheaths were buckled into large macroscopic folds and monoclines with the same NE-trends. The fourth macroscopic folding resulted from shortening along the NE–SW direction, producing mainly NW–SE-trending upright gently plunging folds. Gravitative uplift is disputed as a component of the deformation history of the WHC. The peculiarities of the fold interference pattern result from the interesting behaviour of sheath folds during their refolding.     

Analyzing CO2 emissions mitigation by technology improvement in Central and Eastern Europe

As a legacy of the centrally planned economy, the economies in transition of Central and Eastern Europe (CEE) have a unique potential to reduce their greenhouse gas emissions through the improvement in their high energy intensities. Since much of this `low-hanging fruit' in energy-efficiency improvements can be highly cost-effective, many developed countries facing difficulties in meeting their greenhouse gas (GHG) emission targets domestically are eager to find such opportunities in the CEE region. Therefore, studies analysing the potentials and costs of carbon dioxide reduction through technology improvement in the region have come into the limelight. While there are a few excellent studies in the region aimed at analysing climate change abatement potentials, they all embark on different assumptions, methodologies and boundary conditions. It is hence difficult, if not impossible, to compare and analyse the results of these studies across different authors, countries or time horizons. Consequently, the purpose of this paper is to place four leading studies on GHG mitigation through technology improvement from the CEE region into an internationally comparable framework. Four studies were selected from three countries, Poland, Hungary and Estonia, which are all the results of major national and international efforts to assess costs and potentials of GHG reduction. The paper places their assumptions, methods and final results into a framework which enables policy-makers and project designers to compare these across geographical and technological boundaries. Since other studies from around the globe have been analysed in this framework in the literature, this paper provides a vehicle for the findings of these four studies to be compared to others worldwide. In addition, the paper highlights a few areas where similar studies to be completed in the future in the region may be enhanced by incorporating features used in GHG mitigation research in other parts of the world. This revised version was published online in July 2006 with corrections to the Cover Date.     

陇东地区水土流失与地质作用初步分析

陇东地区是黄河上游水土流失严重区 ,也是国家重点治理的地区之一。由于特殊的岩土体的存在 ,加重了这一地区水土流失作用的危害性。本文通过水土流失现象与地质作用的关系进行偿试性探讨 ,旨在从中找到防治水土流失的有效措施 ,开展治理工作     

华北地台和秦岭—大别—苏鲁造山带的中生代花岗岩与深部地球动力学过程

近年来的研究证实 ,华北地台和大别—苏鲁造山带的中生代花岗岩与同时代的镁铁质超镁铁质岩有类似的Sr、Nd同位素特点 ,许多花岗岩和火山岩还具有类似埃达克岩的地球化学性质。在此基础上 ,根据现已积累的大量Sr、Nd同位素资料 ,从整个华北地台岩石圈的角度论证了中生代岩石圈地幔富集的性质、富集地幔发生的时代及其形成机制 ,进而探讨了岩浆活动的动力学机制 ,指出本区岩石圈富集地幔的形成是在Pangea超大陆裂解时岩石圈大规模拆沉减薄 ,被拆沉的太古宙古老地壳重循环进入地幔改变了地幔成分所致 ,说明超大陆裂解、岩石圈大规模拆沉减薄和富集地幔形成之间有密切的成因联系 ,超大陆裂解伴随着大陆地壳生长和消亡 (重循环 )的大体平衡。结合全球地震层析资料 ,进一步探讨了由俯冲大洋残片转化的下地壳同古老克拉通地壳物质在花岗岩源区中的重要意义。     

新疆东天山地区土屋、延东铜矿地球化学特征与异常查证方法

对土屋地区干旱荒漠景观地球化学条件和勘查地球化学方法进行了分析，对比研究了不同比例尺地球化学异常特征及对矿床的反映能力，指出了该区铜元素是预测铜矿的最重要的指示元素，论证了在区域铜高背景区和异常区开展1：5万化探是进一步定性、定位预测矿区、矿床的重要环节，提出了东天山地区经济、有效的地球化学勘查和异常查证方法技术组合。     

Study of Aeromagnetic Data Over Part of Eastern Ghat Mobile Belt and Bastar Craton

A portion of the aeromagnetic anomaly map of India, from 17⁰ to 20⁰ N and 78^o to 84^o E has been analysed to understand the tectonics of the region. The distribution of magnetic sources in the study region are clearly brought out in the analytic signal map and found to be associated with charnockitic rocks, iron formation and trap flows. The Godavari Graben is devoid of any magnetic sources. High-grade charnockitic rocks on surface and sub-surface, flank the shoulders of the Godavari Graben on either side. From the analysis of magnetic data, Sileru Shear Zone (SSZ) is identified as the contact of the Bastar craton and the Eastern Ghat Mobile Belt (EGMB). The Eastern Ghat is divided into two blocks: Block-N north of Srikakulam is devoid of magnetic sources while the charnockitic rocks are the main magnetic carriers in Block-S. The difference in magnetic characteristics of the two blocks has been attributed to the difference in metamorphic history. Block-N has an over print of amphibolite facies metamorphism while Block-S to the south depicts granulite facies metamorphism. The Euler solutions within the EGMB shows that the magnetic sources along SSZ is shallower than the south east implying that the exhumation process in the EGMB has a differential rate.     

Stability analysis of the Vallcebre translational slide,Eastern Pyrenees (Spain) by means of a GIS

The stability of the landslide of Vallcebre has been evaluated by means of a GIS. The landslide mechanism is a translational failure which has been analysed as an infinite slope. Soil strength parameters and groundwater conditions are obtained from laboratory tests and monitoring devices. Geometric parameters necessary to compute the factor of safety at each individual cell are generated by interpolation from the boreholes present in the landslide. The results have been checked with the actual behaviour of the landslide and are consistent. The comparison between a conventional slope stability analysis and the GIS-based approach gives similar results, showing the feasibility of the latter.