Stable isotope characteristics and origin of ore-forming fluids in copper-gold-polymetallic deposits within strike-slip pull-apart basin of Weishan-Yongping continental collision orogenic belt, Yunnan Province, China     

Wang Yong  Hou Zengqian  Mo Xuanxue  Dong Fangliu  Bi Xianmei  Zeng Pusheng 《Frontiers of Earth Science》2007,1(3):322-332

More than 140 middle-small sized deposits or minerals are present in the Weishan-Yongping ore concentration area which is located in the southern part of a typical Lanping strike-slip and pull-apart basin. It has plenty of mineral resources derived from the collision between the Indian and Asian plates. The ore-forming fluid system in the Weishan-Yongping ore concentration area can be divided into two subsystems, namely, the Zijinshan subsystem and Gonglang arc subsystem. The ore-forming fluids of Cu, Co deposits in the Gonglang arc fluid subsystem have δD values between −83.8‰ and −69‰, δ¹⁸O values between 4.17‰ and 10.45‰, and δ¹³C values between −13.6‰ and 3.7‰, suggesting that the ore-forming fluids of Cu, Co deposits were derived mainly from magmatic water and partly from formation water. The ore-forming fluids of Au, Pb, Zn, Fe deposits in the Zijinshan subsystem have δD values between −117.4‰ and −76‰, δ¹⁸O values between 5.32‰ and 9.56‰, and Δ¹³C values between −10.07‰ and −1.5‰. The ore-forming fluids of Sb deposits have δD values between −95‰ and −78‰, δ¹⁸O values between 4.5‰ and 32.3‰, and Δ¹³C values between −26.4‰ and −1.9‰. Hence, the ore-forming fluids of the Zijinshan subsystem must have been derived mainly from formation water and partly from magmatic water. Affected by the collision between the Indian and Asian plates, ore-forming fluids in Weishan-Yongping basin migrated considerably from southwest to northeast. At first, the Gonglang arc subsystem with high temperature and high salinity was formed. With the development of the ore-forming fluids, the Zijinshan subsystem with lower temperature and lower salinity was subsequently formed. Translated from Mineral Deposits, 2006, 25(1): 60–70 [译自: 矿床地质]  相似文献   

Study of galvanic interactions between pyrite and chalcopyrite in a flowing system: implications for the environment     

Liu Qing You  Li Heping  Zhou Li 《Environmental Geology》2007,52(1):11-18

When galvanic interactions between pyrite and chalcopyrite occur in solution, pyrite, with the higher rest potential, acts as a cathode and is protected whereas chalcopyrite, with the lower rest potential, acts as an anode and its oxidation is increased. In this work a three-electrode system was used to investigate the corrosion current density and mixed potential of a galvanic cell comprising a pyrite cathode and a chalcopyrite anode in a flowing system. The results showed that with increasing concentration of ferric ion in the solution, with increasing acidity, and with increasing flow rate of the solution, the corrosion current density increased and the mixed potential of the galvanic cell became more positive. These experimental results are of direct significance to the control of environmental pollution in mining activity. By using the galvanic model, mixed potential theory, and the Butler–Volmer equation, the experimental results were explained theoretically.  相似文献   

Simulation-optimization approach to assess groundwater availability in Refugio County, TX   总被引：10，自引：0，他引：10  

V. Uddameri  M. Kuchanur 《Environmental Geology》2007,51(6):921-929

Sustainable management of groundwater resources is critical for viable development of semi-arid regions. Refugio County, TX, is predominantly a rural community that is in close proximity to two large urban areas of Corpus Christi and San Antonio. Large-scale water supply projects are being planned to export surplus water available in Refugio County to nearby growing cities. Being a coastal county with several sensitive bays and estuaries, these projects have caused concerns with regard to decreases in freshwater inflows to coastal bodies and raised the possibility of saltwater intrusion. A simulation model characterizing groundwater flow in the shallower unconfined and the deeper semi-confined formations of the Gulf coast aquifer was calibrated and evaluated. The model results were used in conjunction with a mathematical programming scheme to estimate maximum available groundwater in the county. Stakeholder concerns were incorporated as constraints, which included prevention of saltwater intrusion in the aquifer, limiting the amount of allowable drawdown in shallow aquifers, as well as maintaining current flow gradients especially near baseflow-dependent streams and rivers. For the conditions assumed in this study, the model results indicate that roughly 4.93 × 10⁷ m³ of water can be extracted in a typical year. The management model was noted to be very sensitive to the imposed saltwater intrusion constraint.  相似文献   

国内生态环境遥感监测的内容与方法探讨     

陈文惠 《福建地理》2007,(2)

在总结大量实际工作的基础上,就区域生态环境遥感监测的指标与分类系统问题进行了探讨,提出了尽可能与现有的土地利用分类衔接,又较容易进行遥感判读和分类的土地利用分类系统;根据目前国内遥感数据获取和使用情况提出了遥感影像选择、处理以及合成的最佳方案,推荐了通过目视判读和自动分类获得土地利用状况的方法等,以期生态环境遥感监测能真正纳入环保部门常规的监测工作中.  相似文献   

上海城市功能的转型:从全球生产系统角度的透视     

宁越敏  李健 《世界地理研究》2007,16(4):47-54

本文首先回顾了价值链与全球生产系统的研究进展，结合跨国公司最新发展趋势对全球生产系统特征进行了总结；其次以改革开放以来上海对外贸易结构的改变，描述了90年代以来上海在全球生产系统分工中的变化，认为出口产品结构的转型并没有真正改变上海在国际劳动分工中处于低端环节的地位；最后就上海建设世界城市的差距与优势进行了总结，提出全球化发展的外部力量和地方化响应的内部力量将是上海发展世界城市的两个重要驱动力。  相似文献   

福建港口体系结构研究   总被引：2，自引：0，他引：2  

陈斓  伍世代  陈培健 《热带地理》2007,27(3):249-253,283

阐述了福建港湾自然条件和港口开发现状,采用赫希曼-赫芬达尔指数分析近20年来港口体系空间结构的动态演变规律,结果表明,福建港口体系空间结构演变总趋势呈分散化。这说明了港口间的竞争大于合作,职能结构趋同,因而形成合理分工与协作的福建港口群是当务之急。鉴于此,运用模糊聚类、货种区位商等分析技术,对其体系内的港口等级层次、职能结构的基本特征进行探讨,并在此基础上提出了各港口职能分工的发展方向。  相似文献   

国外灾害风险管理对我国城市洪水保险的启示   总被引：3，自引：0，他引：3  

尚志海 《世界地理研究》2007,16(2):107-111

全球变化和城市化的共同作用将导致城市洪涝灾害加剧，在这一新背景下，结合国外灾害风险管理的研究，对洪水保险进行了有益的探索，针对以前我国洪水保险试点在农村地区失败的原因，提议我国应该从城市开始实施洪水保险计划，认为实施城市洪水保险有必要性和可行性，可以进一步拓展城市洪涝灾害风险管理的渠道。  相似文献   

全球城市理论与中国的国际城市建设   总被引：2，自引：0，他引：2  

吕拉昌 《地理科学》2007,27(4):449-456

全球城市是多因素作用的结果,研究范式由20世纪70年代的马克思主义政治经济学向全球与地区相互作用的范式转换。全球城市体系的划分从单一指标向经济与文化结合的多指标方向发展。但如何选取指标,如何进行指标的测量,如何确定各指标的权重分配以及如何采集城市间相互作用的数据与资料,都是全球城市研究要面对的重要问题。中国的全球城市建设要从全球城市体系的等级、位序规律出发,根据社会经济发展的实际,要有步骤、有目标、分阶段,稳步推进,逐步提升城市发展的层次,促进城市国际化的步伐,建设中国的国际城市。  相似文献   

土地节约与集约利用评价研究——以湖南省为例   总被引：1，自引：0，他引：1  

沈彦  刘明亮  雷志刚 《云南地理环境研究》2007,19(4):33-38

土地节约与集约利用是发展循环经济和建设节约型社会的必然要求。首先明确提出土地节约和集约利用评价方法与指标选取原则，完善节约和集约用地的评价指标结构层，特别是农用地和农村宅基地等土地利用类型的评价指标，建立区域和土地利用分区的节约与集约利用土地评价指标体系，以湖南省为例，运用层次分析法，得出湖南省土地节约与集约利用水平的动态变化发展趋势以及农用地集约利用的效益，最后利用加权求和的综合方法，计算出湖南省农用地集约利用水平的综合评价值。  相似文献   

STRUCTURE AND COMPOSITION OF A WATERSHED-SCALE SEDIMENT INFORMATION NETWORK     

W. R. OSTERKAMP J. R. GRAY J. B. LARONNE J. R. MARTIN 《国际泥沙研究》2007,22(3):238-246

A "Watershed-Scale Sediment Information Network" (WaSSIN), designed to complement UNESCO’s International Sedimentation Initiative, was endorsed as an initial project by the World Association for Sedimentation and Erosion Research. WaSSIN is to address global fluvial-sediment information needs through a network approach based on consistent protocols for the collection, analysis, and storage of fluvial-sediment and ancillary information at smaller spatial scales than those of the International Sedimentation Initiative. As a second step of implementation, it is proposed herein that the WaSSIN have a general structure of two components, (1) monitoring and data acquisition and (2) research. Monitoring is to be conducted in small watersheds, each of which has an established database for discharge of water and suspended sediment and possibly for bed load, bed material, and bed topography. Ideally, documented protocols have been used for collecting, analyzing, storing, and sharing the derivative data. The research component is to continue the collection and interpretation of data, to compare those data among candidate watersheds, and to determine gradients of fluxes and processes among the selected watersheds. To define gradients and evaluate processes, the initial watersheds will have several common attributes. Watersheds of the first group will be: (1) six to ten in number, (2) less than 1000 km2 in area, (3) generally in mid-latitudes of continents, and (4) of semiarid climate. Potential candidate watersheds presently include the Weany Creek Basin, northeastern Australia, the Zhi Fanggou catchment, northern China, the Eshtemoa Watershed, southern Israel, the Metsemotlhaba River Basin, Botswana, the Aiuaba Experimental Basin, Brazil, and the Walnut Gulch Experimental Watershed, southwestern United States.  相似文献