Interaction in the water-rock system as a new basis for the development of hydrogeology

This paper addresses the main mechanisms controlling the continuous and geologically long evolution of the water-rock system, which produced diverse hydrogenous mineral complexes. The concept of such complexes was introduced by the author. It was shown that the water-rock system is a steady-state and equilibrium-disequilibrium one. Its development occurs in a far from equilibrium region and results in the formation of fundamentally new mineral associations and geochemical types of water. Taking into account that water is the main factor controlling the evolutionary trend of this system, it is argued that this system must be among the most important targets of hydrogeology.     

鄂尔多斯盆地陇东地区延长组的物源分析

笔者从区域沉积背景入手,对鄂尔多斯盆地陇东地区长3油层组泥岩稀土元素、碳酸盐岩岩屑、轻重矿物、砂岩粒度等进行综合分析研究,认为研究区内存在混合物源,物源方向主要有北东向和西南向,并初步判断,北东物源的边界大致在南梁-华池地区,西南物源的边界大约在悦乐地区。     

基于数字地质调查系统的矿产远景调查数据库建设——内蒙古达来庙矿产远景调查项目数据库的建设和体会

2007年5月由中国地质调查局主管部门建议．选定内蒙古达来庙地区的矿产远景调查项目作为矿产远景调查数据库系统应用的试点项目,全面开展了矿调数据库的建设。根据矿调工作的特点．项目利用数字地质调查系统完成了①地质填图野外数据PRB库;②实际材料图数据库;③地质矿产图空间数据库;④地球化学数据库;⑤地球物理数据库;⑥遥感数据库;⑦综合成果数据库和⑧大比例尺综合图数据库的建设,从而实现了将矿调工作原始资料、成果资料集于数字地质调查系统同一平台下的全部数字化。     

南图尔盖盆地储层成岩作用及孔隙演化

储层储集性能普遍良好是南图尔盖盆地油气资源丰富的主要原因.通过对该盆地储层的岩石学特征、成岩作用及孔隙类型演化分析研究发现,砂岩的成岩作用及孔隙演化对储层的储集性能有着重要影响.在对大量薄片和岩心进行分析的基础上,运用扫描电镜和X衍射粘土分析等手段,对南图尔盖盆地砂岩储层研究结果表明,该区机械压实和压溶作用、杂基充填作用、胶结作用和交代作用使砂岩孔隙度降低,不稳定矿物的溶蚀作用导致储层次生孔隙发育.根据有机质的演化及粘土矿物的变化序列,成岩作用和孔隙演化随埋深具有明显的阶段性:早成岩阶段,孔隙类型以原生孔隙粒间孔为主;中成岩阶段,孔隙类型以原生、次生混合型为主;晚成岩阶段,孔隙类型以次生型为主.综合评价南图尔盖盆地储层发现,阿雷斯库姆组、阿克萨布拉克组和库姆科尔组为Ⅰ类储层,可作为今后油气勘探的主要目的层.     

Experimental Investigation of the Upper Thermal Stability of Mg-rich Actinolite; Implications for Kiruna-Type Iron Deposits

The occurrence of actinolite in magnetite deposits of possiblemagmatic origin has prompted an experimental investigation ofthe upper thermal stability of Mg-rich actinolite to determinehow the stability of actinolite changes with increasing Fe content.Experiments were carried out primarily on the compositionalre-equilibration of natural tremolite [molar Fe/(Fe + Mg) =Fe-number = 0·014] in the presence of synthetic clinopyroxene(Ca_0·80Fe_0·67Mg_0·54Si_2·00O₆), syntheticpigeonite/orthopyroxene (Ca_0·08Fe_1·19Mg_0·70Si_2·02O₆),quartz, and water to a more Fe-rich actinolite over the rangeof 600–880°C, 1 and 4 kbar, at the Ni–NiO oxygenbuffer, for durations of 1–2 weeks. The bulk compositionof the mineral mixture is close to actinolite with Fe-number= 0·5. These experiments constitute a half-reversal ofthe amphibole composition, which, when approached from a Mg-richstarting composition, provides information on the minimum Fecontent of actinolite at a given temperature. Compositionalchanges were monitored by electron microprobe analysis of amphibolerim compositions and/or overgrowths on the original tremolite.At 4 kbar and 880–800°C, tremolite shows strong re-equilibrationwith overgrowths of an Fe-rich but low-Ca (1·7 > Ca> 1·4) actinolite; Fe-rich cummingtonite (Ca <0·7)begins to nucleate at 860°C. At 800–700°C, tremoliteshows weak compositional re-equilibration but strong nucleationof Fe-rich cummingtonite. Similar results were observed at 1kbar, with tremolite showing strong re-equilibration to low-Caactinolite at 790–600°C with cummingtonite nucleationat 800°C and below. The wide variation in Ca contents ofthe re-equilibrated amphiboles was unexpected. Additional univariantreversal experiments were carried out on the thermal decompositionof a natural actinolite (Fe-number = 0·22) from PleitoMelón, Chile, indicating the breakdown of actinoliteto clinopyroxene, orthopyroxene, quartz, and water at 780°Cand 1 kbar, and 850°C and 4 kbar. Considering only amphiboleswith Ca >1·7 a.p.f.u., the thermal stability of actinoliteis observed to decrease in a linear manner over the P–Trange investigated with a dT/dFe-number slope of –372°C/Fe-numberat 1 kbar and –546°C/Fe-number at 4 kbar. The highthermal stabilities (750–900°C) of actinolites withFe-numbers in the range of 0–0·4 overlap with therange of water-saturated melting for a typical andesite or tonalite.These conditions also overlap the field of experimental Fe–P-richmelt formation, suggesting that actinolite may have an igneousorigin in Kiruna-type ore deposits. KEY WORDS: actinolite; mineral stability; Kiruna deposits, thermodynamic values; cummingonite     

基于矿物光谱指数的蚀变信息提取——以西藏多龙铜金矿集区ASTER数据为例

矿物光谱指数是利用比值的方法增强Fe和含OH矿物在可见光、短波红外区间的吸收特征,进而提取蚀变矿物信息的一种方法。由于斑岩型矿床的蚀变分带特征明显,西藏多龙矿集区中集中了斑岩型、浅成低温热液型等铜、金矿床,通过矿物光谱指数的计算提取相关蚀变信息,对该区域的下一步找矿具有指导意义。本文采用矿物光谱指数(5+7)/6、(6+9)/8等方法提取了镁、铝两类羟基及铝羟基类下的高岭石等蚀变信息,采用5/4、2/1的方法提取了二价铁、三价铁的蚀变信息。经过与OLI影像采用PCA方法及野外实地勘查采样,证实了利用本文方法所提取的蚀变信息有效。     

环境矿物界面反应动力学

环境矿物界面反应动力学主要探讨地表中各种有毒、有害离子或分子与矿物表面之间的反应速率与反应机制。矿物表面存在一组化学活性很强的表面功能基，当它们与环境中毒害物质发生作用时，会因其极性、荷电性和Lewis酸碱性不同而表现出不同的作用力和反应速率，进而控制有毒、有害物质在大气、水体和沉积物中的赋存形态，稳定性及迁移转化速率。本文简要介绍了环境矿物界面反应动力学理论，并给出几个应用实例。     

吐哈盆地侏罗系砂岩储层中粘土矿物组成和分布的控制因素

在大量分析数据基础上，总结了吐哈盆地侏罗系砂岩储层中粘土矿物组成及其在纵横向上的分布特征，重点对吐哈盆地侏罗系岩储层中粘土矿物组成和分布的主控因素进行了分析，笔者认为吐哈盆地的成岩过程中砂岩孔隙介质条件，不同沉只环境砂体渗滤条件的差异，盆地的大地构造背景和构造发育史以及盆地演化过程中的古气候变化等是影响盆地砂岩粘放物组成和分布的主控因素。由此可以为寻找有利储层和设计酸化采油方案提供重要的依据。     

Quantitative Analysis of Mineral Resources for Strategic Planning: Implications for Australian Geological Surveys

A quantitative valuation study has been made of Australian state surveys with the specific goals of (1) establishing the 'worth' of current programs upgrading state government geoscientific information infrastructure, and (2) considering the results of the valuation in terms of strategic planning. The study has been done from the perspective of the community as a whole and has been undertaken in two phases reflecting the different objectives of Australian state surveys in terms of the exploration industry and government policy-making. This paper reports on the second part of this valuation process, measuring the impact of upgraded survey data on government mineral policy decision processes. The valuation methodology developed is a comparative approach used to determine net benefit foregone by not upgrading information infrastructure. The underlying premise for the geological survey study is that existing and upgraded data sets will have a different probability that a deposit will be detected. The approach used in the valuation of geoscientific data introduces a significant technical component with the requirement to model both favorability of mineral occurrence and probability of deposit occurrence for two different generations of government data. The estimation of mineral potential uses modern quantitative methods, including the U.S. Geological Survey three-part resource-assessment process and computer-based prospectivity modeling. To test the methodology mineral potential was assessed for porphyry copper type deposits in part of the Yarrol Province, central Queensland. Results of the Yarrol case study supports the strategy of the state surveys to facilitate effective exploration by improving accuracy and acquiring new data, as part of resource management. It was determined in the Yarrol Province case study that in going from existing to upgraded data sets the area that would be considered permissible for the occurrence of porphyry type deposits almost doubled. The implication of this result is that large tracts of potentially mineralized land would not be identified using existing data. Results of the prospectivity modeling showed a marked increase in the number of exploration targets and in target rankings using the upgraded data set. A significant reduction in discovery risk also is associated with the upgraded data set, a conclusion supported by the fact that known mines with surface exposure are not identified in prospectivity modeling using the existing data sets. These results highlight the absence in the existing data sets of information critical for the identification of prospective ground.Quantitative resource assessment and computer-based prospectivity modeling are seen as complementary processes that provide the support for the increasingly sophisticated needs of Australian survey clients. Significant additional gains to the current value of geoscientific data can be achieved through the in-house analysis and characterization of individual data sets, the integration and interpretation of data sets, and the incorporation of information on geological uncertainty.