澳大利亚铀矿的成矿区划、矿床类型及找矿前景

澳大利亚蕴藏了丰富的铀矿资源,目前铀矿储量位居世界第二。在大地构造上,澳大利亚可划分为中西部前寒武纪克拉通和东部显生宙造山带。在区域地质构造背景和成矿条件研究的基础上,总结了铀矿在北澳、南澳、西澳、中澳和东澳五大成矿区带中的分布情况,勾勒了北澳的派恩克里克、南澳的奥林匹克坝、西澳的伊利列等15个矿集区中的34个类型迥异的矿区的总体地质环境与矿床特征。根据成矿地质作用、成因类型、矿物特征等因素,结合该国铀矿床的具体情况,归纳出8种典型的矿床类型。选取代表性铀矿进行地质环境、矿床地质的分析与总结,认为澳大利亚铀矿的成矿地质条件优越,矿床类型丰富,资源潜力巨大,并指出这些类型可作为今后找铀的靶向类型。     

Analysis of hydrogeolgical characteristics and water environmental impact pathway of typical shale gas exploration and development zones in Sichuan Basin,China

Studying the influence of shale gas exploration and development on groundwater environment is the basis of guiding water environment protection in the process of shale gas exploration and development. Groundwater environmental pollution is concealed, complex and persistent. Once it is difficult to control the pollution, the current commercial shale gas development zones in Sichuan Basin that are mostly located in karst areas and highly sensitive to groundwater will be vulnerable to the impact of shale gas exploration and development. Based on the hydrogeological conditions of shale gas exploration and development area and combined with engineering analysis of exploration and development, various risk pathways that may affect the groundwater environment during process of shale gas exploration, mining well construction, mining operations and other stages were identified in this paper. Some existing risk pathways were proved by verification of typical areas and should not be ignored. Based on the actual situation of typical areas, the countermeasures of groundwater environmental protection in the process of shale gas exploration and development in karst areas were discussed. It is believed that the ground-water environment can be better protected by strengthening administration, research and application of new technologies, precise design, hydrogeological conditions, and research and feedback of groundwater environmental protection.     

Paragenesis and geochemistry of ore minerals in the epizonal gold deposits of the Yangshan gold belt,West Qinling,China

Six epizonal gold deposits in the 30-km-long Yangshan gold belt, Gansu Province are estimated to contain more than 300 t of gold at an average grade of 4.76 g/t and thus define one of China's largest gold resources. Detailed paragenetic studies have recognized five stages of sulfide mineral precipitation in the deposits of the belt. Syngenetic/diagenetic pyrite (Py₀) has a framboidal or colloform texture and is disseminated in the metasedimentary host rocks. Early hydrothermal pyrite (Py₁) in quartz veins is disseminated in metasedimentary rocks and dikes and also occurs as semi-massive pyrite aggregates or bedding-parallel pyrite bands in phyllite. The main ore stage pyrite (Py₂) commonly overgrows Py₁ and is typically associated with main ore stage arsenopyrite (Apy₂). Late ore stage pyrite (Py₃), arsenopyrite (Apy₃), and stibnite occur in quartz ± calcite veins or are disseminated in country rocks. Post-ore stage pyrite (Py₄) occurs in quartz ± calcite veins that cut all earlier formed mineralization. Electron probe microanalyses and laser ablation-inductively coupled plasma mass spectrometry analyses reveal that different generations of sulfides have characteristic of major and trace element patterns, which can be used as a proxy for the distinct hydrothermal events. Syngenetic/diagenetic pyrite has high concentrations of As, Au, Bi, Co, Cu, Mn, Ni, Pb, Sb, and Zn. The Py₀ also retains a sedimentary Co/Ni ratio, which is distinct from hydrothermal ore-related pyrite. Early hydrothermal Py₁ has high contents of Ag, As, Au, Bi, Cu, Fe, Sb, and V, and it reflects elevated levels of these elements in the earliest mineralizing metamorphic fluids. The main ore stage Py₂ has a very high content of As (median value of 2.96 wt%) and Au (median value of 47.5 ppm) and slightly elevated Cu, but relatively low values for other trace elements. Arsenic in the main ore stage Py₂ occurs in solid solution. Late ore stage Py₃, formed coevally with stibnite, contains relatively high As (median value of 1.44 wt%), Au, Fe, Mn, Mo, Sb, and Zn and low Bi, Co, Ni, and Pb. The main ore stage Apy₂, compared to late ore stage arsenopyrite, is relatively enriched in As, whereas the later Apy₃ has high concentrations of S, Fe, and Sb, which is consistent with element patterns in associated main and late ore stage pyrite generations. Compared with pyrite from other stages, the post-ore stage Py₄ has relatively low concentrations of Fe and S, whereas As remains elevated (2.05～3.20 wt%), which could be interpreted by the substitution of As^? for S in the pyrite structure. These results suggest that syngenetic/diagenetic pyrite is the main metal source for the Yangshan gold deposits where such pyrite was metamorphosed at depth below presently exposed levels. The ore-forming elements were concentrated into the hydrothermal fluids during metamorphic devolatilization, and subsequently, during extensive fluid–rock interaction at shallower levels, these elements were precipitated via widespread sulfidation during the main ore stage.     

Two types of multiple solutions for microseismic source location based on arrival-time-difference approach

The arrival-time-difference approach is the dominant source location approach used in the microseismic source location area. Multiple solutions problem is one of the major concerns in microseismic source location, which is closely related to the microseismic network. This paper categorizes the multiple solutions into two types based on the origin times when using the arrival-time-difference approach. Type I multiple solutions are those which have the same origin time; type II multiple solutions are those with different origin times. The sufficient and necessary conditions to produce type I multiple solutions are that all sensors are located in a straight line for two-dimensional cases and on a plane for three-dimensional cases. The sufficient and necessary conditions to produce type II multiple solutions are that all sensors are located on a hyperbola for two-dimensional cases and on a hyperboloid for three-dimensional cases. Furthermore, the proofs indicate that type I multiple solutions are preventable, while a microseismic network consisting of the minimum number of sensors can never be free of type II multiple solutions. It means, besides the minimum number of sensors, at least one more sensor which is not on this hyperbola or hyperboloid is needed to uniquely determine a source. The results from field tests and applications indicate that when the sensors of a network lie on a hyperbola, the type II multiple solutions may not be the necessary outcome under the influence of errors in real data. However, the accuracy of the microseismic source location is affected significantly by this kind of networks. The results also show that not only the multiple solutions problem can be avoided effectively, but more importantly, the accuracy of the source location will be greatly improved by the optimization of network based on the characteristics of the microseismic network and field conditions.     

北冈底斯带日土县-拉梅拉山口花岗岩体的岩石地球化学特征、锆石U-Pb测年及Hf同位素组成

对西藏西部日土县城以南-拉梅拉山口一带的花岗岩体开展了详细的岩相学、岩石地球化学和锆石U-Pb年代学及Hf同位素研究。所有样品铝饱和指数A/CNK集中在0.76~1.0之间,为准铝质类型。CIPW标准矿物组合为Q+Or+Ab+An+Di（或C）+Hy。在稀土元素配分图中呈现出右倾缓倾斜型的特征,轻稀土元素富集并出现较强的分馏作用,重稀土元素无分馏-轻微分馏。δEu在0.56~0.99范围之间,属于铕亏损型。大离子亲石元素出现分化,富集Rb、Pb、Th而亏损K、Ba,高场强元素Nb、Ta、Ti等明显亏损。获得钾长花岗岩、二长花岗岩及花岗闪长岩中岩浆结晶锆石的LA-ICP-MS U-Pb年龄分别为：79.4±0.4Ma、 81.0±0.5Ma和81.3±0.5Ma,结合锆石稀土元素和岩浆振荡环带特征及Th/U比值,上述年龄结果可代表岩石的结晶年龄,表明该套岩体为晚白垩世侵位的大型岩基。两件样品的锆石均具有正的Hf同位素初始比值ε_Hf（t）,两阶段Hf模式年龄（t_DM2）分别介于547.5~658.0Ma、523.4~710.2Ma之间。分析认为该套岩体的物质来源应该为富角闪石的下地壳,可能为幔源岩浆首先侵入到地壳基底岩石中形成新生地壳,然后在温度约为700~800℃之间、压力<8kbar且富含流体的影响下,这种既有新生地壳又有古老基底地壳构成的混合地壳发生部分熔融而形成。这一结论与野外宏观露头上岩体中大量发育暗色微粒包体等直接岩石学证据相佐证。结合区域构造演化及岩体所处的大地构造位置,该套花岗岩体应该形成于洋壳闭合时的碰撞造山过程,其形成与侵位与北侧班公湖-怒江结合带的构造演化有成因上的联系,是班公湖-怒江特提斯洋向南的俯冲碰撞的产物。     

The Influence of Pan Evaporation Conditions on Na Cl crystallization

正1 Introduction Crystallization is one of important unit operations in the chemical production process,which requires not only the crystal product with high purity and yield,but also the available particle size of the crystal products to ensure product quality.Crystallization process is affected by     

Research of Recycled Salt and Glauber’ Salt Precipitation Rules of Yabulai Salt Lake Brine

正1 Introduction The main production of Yabulai salt lake was original salt and recycled salt many years ago.After decade’s production,the sale lake resource is more and more deficient.Glauber's salt and magnesium salt are concentrated in brine now.It could affect the quality of the salt.In recent years,research had done much work to     

Synthesis and Characterization of an Extractant [Bmim]PF_6 for Lithium Ion

正With the rapid increasing demand of metal lithium and its compounds in science and technology,studies on lithium recovery though lithium ion extraction from salt lake brines are blooming bacause more than 60 percent of     

松嫩平原(吉林省)地下水动态特征及类型的研究

根据松嫩平原(吉林省)地下水动态观测资料进行分析,对区内的主要供水含水层的动态特征进行了描述,并对其进行了动态类型的划分,结合地下水动态的主要影响因素将为研究区地下水动态预测及地下水资源管理提供了依据。     

基于FloodArea模型的暴雨洪涝灾害风险预评估技术及效果检验北大核心CSCD

利用陕西气象站点逐小时降水实况、精细化格点预报、数字高程、土地利用、灾情等资料,应用水动力模型FloodArea对暴雨洪涝进行淹没模拟,在淹没水深和范围的基础上叠置承灾体属性,引入承灾体的灾损曲线,建立暴雨洪涝灾害风险预评估模型,并从数量占比和灾情占比两个角度,以县为单元进行验证,利用格点降水量预报对陕西6次大范围暴雨过程灾害风险进行预评估以及效果检验。结果表明:暴雨洪涝气象风险预估结果与实际受灾地区分布基本吻合,正确预报率73.2%,模拟结果可信度高,对于降水区域集中暴雨的风险预评估性能较分散性暴雨较高,漏报率相对低,但是空报率较高;建立的暴雨洪涝灾害风险预评估及效果检验流程,提高了气象服务的针对性,可以用于洪涝风险预评估的实际业务中,对暴雨洪涝风险管理提供技术支撑。