Fluorite deposits at Encantada–Buenavista, Mexico: products of Mississippi Valley type processes

Petroleum and aqueous fluid inclusions from the Encantada–Buenavista fluorite mineralized zone in northern Mexico were analyzed by microthermometry, UV fluorescence, Raman Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR) and Confocal Scanning Laser Microscopy (CSLM) to evaluate the geochemical evolution of the mineralizing fluids. Two-phase (petroleum or brine+vapor) and three-phase (petroleum+brine+vapor) inclusions are described. Aqueous and petroleum-rich inclusions commonly occur in the same plane. Vapor-decrepitated and stretched fluid inclusions are present. A low-salinity methane-saturated fluid and a high salinity-fluid with highly variable methane contents are recognized. H₂S is not quantified but is always detected in close association with methane. Petroleum inclusions are of two types: a low methane petroleum fluid (20 mol%) with low T_h (60 °C) and a petroleum fluid with a methane of content near 30 mol% and a T_h of 90 °C.Pressure and temperature diagrams for the aqueous and petroleum inclusions show three main intersects that allow P–T–X reconstruction of fluid evolution at La Encantada–Buenavista. A CH₄- and H₂S-rich low-salinity brine was mixed with oil that migrated under hydrostatic conditions with a thermal gradient of 70 °C/km. The arrival and mixing of a high-salinity aqueous fluid produced overpressure to 300 bars. A return to hydrostatic conditions was accompanied by an increase in the thermal gradient.The brine related to the fluorite orebodies appears to have a genetic relationship with the brines reported from the Jurassic petroleum basins located west of the fluorite bodies and similarities with reported fluids from Mississippi Valley type deposits. It is interpreted that the fluorine-rich fluids migrated toward the platform margins during the mid-Tertiary (30 to 32 Ma) using extension zones related to Basin and Range tectonism. Mixing of two different brines was responsible for precipitation and mineralization. Heat from magmas, related to tectonic extension, caused decrepitation and changes in the shape of fluid inclusions near the contact zones.     

福建省地震局FTP服务器的建设与管理

本文介绍省局FTP服务器技术系统的构建和管理 ,以及如何在地震监测预报的业务处理工作中更有效地利用该系统进行数据和信息资源共享。     

河砂资源过度开采对水环境的破坏暨环境地质问题--以山东大汶河河砂开采为例

河砂既是矿产资源，也是宝贵的环境资源，具有涵养水分、保护环境的作用。河砂资源的过度开采，既引起了河岸坍塌地质灾害，又对沿河水环境特别是地下水环境造成破坏。大汶河河砂开采造成了河岸坍塌、河桥报废。使沿河第四系孔隙水和旧县水源地岩溶地下水水位下降，地下水开采资源减少，水质变差。分析结果表明，大汶河河砂的过度开采，不利于环境保护、不利于长远经济和社会效益，应予取缔或严格限制开采规模。     

地下开采条件下水资源流失机理与环境影响研究

通过剖析因地下采动造成阜新矿区自然村民井断水现象，对地下开采条件下水资源流失与恶化机理进行了分析研究。结果表明，即使采空区和受影响区处于不同的水文地质单元，因采动对隔水构造的破坏而形成地下水径流通道-空巷和裂隙，从而为水的流失创造了水文地质条件；地下水经过长时间聚集和物化作用发生水质恶化，失去使用价值。废弃关闭矿井水的资源化与利用问题，对水资源缺乏和煤炭资源枯竭、经济转型矿区具有现实的经济与社会意义。应该研究因抽取矿井水而引起的相关环境影响与灾害问题，防止出现二次破坏。     

GIS Predictive Model for Producing Hydrothermal Gold Potential Map Using Weights of Evidence Approach in Gengma Region, Sanjiang District, China

Gengma region, Sanjiang district is known to have some large-scale gold deposits. GIS predictive model for hydroghermal gold potential was carried out in this region using weights of evidence modeling technique. Datasets used include large-scale hydroghermal gold deposit records, geological, geophysical and remote sensing imagery. Based on the geological and mineral characteristics of areas with known gold occurrences in Sanjiang, several geological features were thought to be indicative of areas with potential for the occurrence of hydroghtermal gold deposits. Indicative features were extracted from geoexploration datasets for use as input in the predictive model. The features include host rock lithology, geologic structures, wallrock alteration and associated (volcanic-plutonic) igneous rocks. To determine which of the indicative geological features are important spatial predictors of area with potential for gold deposits, spatial analysis was done through the modeling method. The input maps were buffered and the optimum distance of spatial association for each geological feature was determined by calculating the contrast and studentized contrast. Five feature maps were converted to binary predictor patterns and used as evidential layers for predictive modeling. The binary patterns were integrated in two combinations, each of which consists of four patterns in order to avoid over prediction due to the effect of duplicate features in the two structural evidences. The two produced potential maps define almost similar favorable zones. Areas of intersections between these zones in the two potential maps placed the highest predictive favorable zones in the region.     

网络环境下的极地科学信息资源探索

互联网的极地科学信息资源主要包括极地搜索引擎、组织机构和研究项目、科学研究成果 (各种数据库、电子期刊和网上出版物 )。通过对极地科学网站信息的查询探索 ,揭示网络环境下极地科学信息资源的现状 ,提出建立网络极地信息资源导航的意义及实现途径     

RS GIS与计算机技术在土地资源综合调查中的应用及效果评述

采用RS、GIS和计算机技术3者相结合的方法，对广东省土地资源进行了首次综合调查。结果表明：该方法速度快、费用少、数据准确可靠，成果资料实现了现代化管理模式，调查结果能满足我国社会主义经济建设快速发展的需要。     

Comparison of Two Probability Distributions Used to Model Sizes of Undiscovered Oil and Gas Accumulations: Does the Tail Wag the Assessment?

Undiscovered oil and gas assessments are commonly reported as aggregate estimates of hydrocarbon volumes. Potential commercial value and discovery costs are, however, determined by accumulation size, so engineers, economists, decision makers, and sometimes policy analysts are most interested in projected discovery sizes. The lognormal and Pareto distributions have been used to model exploration target sizes. This note contrasts the outcomes of applying these alternative distributions to the play level assessments of the U.S. Geological Survey's 1995 National Oil and Gas Assessment. Using the same numbers of undiscovered accumulations and the same minimum, medium, and maximum size estimates, substitution of the shifted truncated lognormal distribution for the shifted truncated Pareto distribution reduced assessed undiscovered oil by 16% and gas by 15%. Nearly all of the volume differences resulted because the lognormal had fewer larger fields relative to the Pareto. The lognormal also resulted in a smaller number of small fields relative to the Pareto. For the Permian Basin case study presented here, reserve addition costs were 20% higher with the lognormal size assumption.     

西部有色金属矿产资源潜力与矿业发展战略

通过近二十年来我国有色金属矿产资源与矿业生产态势的分析对比，发现我国西部有色金属矿产资源潜力较大，近期可利用资源多，蕴藏较集中，具有较好的资源优势和一定的有色金属工业基础。指出应着重采取资源的优化配置、生产要素的优化配置、技术创新型战略和资源节约型战略，以推动西部矿业发展。     

天然气水合物的资源环境效应

天然气水合物是一种具有巨大潜能的绿色能源 ,全世界储量接近 0 .84× 10 1 8m3。由于天然气水合物具有特殊亚稳定状态的成矿系统 ,,增温或减压会使捕获的气体释放 ,导致海底滑塌和滑坡等地质灾害 ,以及作为“温室气体”对人类生存环境的严峻挑战 ,因而其又具有环境效应。结合挪威的实例论述了天然气水合物的资源和环境双重效应