陕西大石沟碳酸岩脉型钼(铅)矿床围岩蚀变探讨

东秦岭金堆城—南泥湖以钼为主的多金届成矿带是我国主要的钼成矿带之一。它不仅拥有驰名中外的金堆城斑岩型钼矿床,而且有南泥湖斑岩—矽卡岩型钼(钨)矿床、大石沟碳酸岩脉型钼(铅)矿床,以及石家湾斑岩型钼矿床等。其中大石沟碳酸岩脉型钼(铅)矿床是本区一种新的成因类型钼矿床。本文仅对其围岩蚀变特征进行探讨,有错之处,望批评指正。一、矿床地质概况矿床位于中朝准地台南缘的豫陕断隆区内。该断隆区内前寒武纪地层经历了多次复杂     

陕西省洛南县莲花沟岩体地质、物化特征及含矿性分析

位于华北地台南缘的东秦岭钼矿带是中国重要的大型钼矿分布区之一(图1),钼矿带西起陕西省的金堆城地区,东至河南省栾川南泥湖-三道庄-上房沟、嵩县雷门沟地区,该矿带产出了金堆城、南泥湖、三道庄、上房沟等超大型钼矿床和雷门沟等10余个钼(钨)多金属矿床,钼储量约占全国总储量的52%.此外,斑岩钼矿床内还伴有钨、铅、稀土、金、铀等元素的矿化,如南泥湖钼矿中伴生的钨达到超大型规模,其储量位居中国第二.同样位于该带的东段河南境内的栾川一带在找矿方面都有很大的突破,而位于该带的西段陕西境内的洛南一带除了金堆城、黄龙铺在找矿方面取得突破外,在其他地方几乎没什么大的进展.同一个成矿带、同样的成矿条件和构造地质背景,为什么会存在这么大的差别呢?按成矿理论不可能到洛南莲花沟一带就突然尖灭.着眼于区域地质背景,寻找成矿有利地段,可望取得找矿新突破.     

陕西黄龙铺—河南栾川地区钼矿床地质特征及控矿因素

本文对陕西省黄龙铺—河南省栾川钼矿带区域成矿背景作了简述。在矿带内分出了金堆城—黄龙铺、夜长坪—银家沟、南泥湖—栾川三个钼矿集中区。将钼矿分为两个成矿系列（碱基性碳酸岩岩浆成矿系列,中酸性岩浆—热液成矿系列）,三种成因类型（碳酸岩脉型、斑岩型、矽卡岩型或斑岩—矽卡岩型）,四个成矿期次（海西—印支期碳酸岩脉型钼成矿期,燕山早期第一阶段矽卡岩型钼成矿期,燕山早期第二阶段—燕山晚期斑岩型钼成矿期,燕山晚期岩浆期后热液脉型成矿期）。以典型矿床（点）为例,配以大量的图、表,对不同类型的矿床特征作了介绍。总结了6条成矿规律,6条找矿标志,指出了10个找矿有利区。认为华北地台南缘地壳深部存在一个以钼为主的成矿元素“流体库”及岩浆源,成矿物质来源于地壳深部及上地幔。     

金堆城-黄龙铺钼矿田地球化学特征及成矿条件的初步分析

金堆城-黄龙铺钼矿田面积约120公里~2,区内分布有金堆城钼矿,规模极大.石家湾、黄龙铺钼矿,尚处于详查阶段,储量也较大.宋家沟等处都是有找矿前景的矿(化)点.总之,矿田内钼矿总资源储量可观. 金堆城为斑岩型钼矿床.对黄龙铺目前有两种意见:①认为与斑岩型同源,属广义的斑岩型钼矿床;②认为与斑岩型不同源,属非岩浆热液石英脉型钼矿床. 矿床、矿(化)点分布于长城系熊耳群和蓟县系高山河组岩层中.曾有人提出“矿源层”问题. 本文在已有工作基础上,初步总结了矿田地球化学特征,并对成矿条件作初步分析.     

河南省肖畈钼矿地质特征及动力学背景

肖畈钼矿床是东秦岭-大别山地区典型的斑岩型钼矿床.与矿床有关的小侵入岩为肖畈岩体.岩体分两期侵入,第一期为花岗斑岩,第二期为斑状花岗岩.矿石中金属矿物以辉钼矿、黄铁矿为主,脉石矿物以石英为主,矿石构造有细脉状、浸染状及团块状.矿床成矿年龄为142 Ma.其与金堆城钼矿、南泥湖钼矿等斑岩型钼矿均形成于早白垩世,可归为东秦岭-大别山钼矿带第2成矿期,是印支期后大别造山带构造体制从挤压收缩向区域性伸展的成矿事件.     

就若干矿床的类型、成矿物质来源及辉钼矿含铼量的地质意义等与毛景文研究员商榷

毛景文研究员等多年来将陕西洛南黄龙铺碳酸岩脉型钼(铅)矿床分别更改为碳酸盐(岩)型、热液碳酸盐脉型或脉型,把河南栾川南泥湖斑岩体形成复合的南泥湖—三道庄斑岩—夕卡岩型钼(钨)矿床,分解为南泥湖斑岩钼钨矿床和三道庄夕卡岩型钼钨矿床,和把长江中下游地区的绝大多数夕卡岩型铜(铝)矿床和少数斑岩—夕卡岩型铜(钼)矿床更改为斑岩—夕卡岩—层控铜—金—钼矿床等。本文对毛景文等更改这些矿床的矿床类型,以及毛景文等认为"辉钼矿的Re含量可指示成矿物质来源","大水沟热液型碲(金)矿床的成矿流体及其他物质主要来自于地幔"和"温泉钼矿是与S-型花岗岩有关的斑岩钼矿床是一种新类型和新发现"等所存在的问题进行探讨。希能理清某些矿床学问题,进一步促进矿床学的发展。     

东秦岭南泥湖钼（钨）矿床和秋树湾铜（钼）矿床成岩成矿特征对比研究

东秦岭钼矿带内的南泥湖钼（钨）矿床和秋树湾铜（钼）矿床同为斑岩型矿床,地理位置相近,却在成矿类型和规模上差异显著。通过对两个矿床的矿床地质特征、成矿斑岩体的地球化学特征、成矿时代及其成矿物质来源（S同位素、流体包裹体和Re含量）进行对比分析,确定南泥湖钼（钨）矿床和秋树湾铜（钼）矿床类型均为壳幔混源型,后者成岩成矿过程有更多的幔源物质参与,并且两个矿床同时形成于秦岭造山带中生代燕山期伸展减薄的机制下,但所处构造单元（华北陆块南缘和北秦岭）不同,以上这些都导致了成矿的差异性,并为日后在东秦岭钼矿带中钼铜两类矿床的找矿工作提供参考。     

东秦岭木龙沟夕卡岩型铁多金属矿床含矿岩体的成因研究

东秦岭地区是世界上最大的钼矿带,已发现东沟、金堆城、南泥湖、上房沟等5个世界级钼矿床,探明钼金属量达500万t以上(李诺等,2007;Mao et al.,2008;陈衍景等,2009)。除斑岩型钼矿外,本地区还发育众多夕卡岩型铁铜多金属矿床(如木龙沟铁矿床、黑山铁铜矿床、八宝山铁     

东秦岭斑岩型钼矿床的地质特征及成因探讨

东秦岭钼成矿带是我国14个大型钼成矿带中最重要的成矿带[1],其规模可与北美的科罗拉多地区钼矿带相媲美.世界上六大钼矿就有两个在东秦岭地区,分别为河南栾川(储量为130万t)和陕西金堆城(储量为97万t).该钼矿带西起陕西省金堆城,东至河南省栾川南泥湖、嵩县雷门沟一带.成矿带中所发现的钼矿床,其成因类型主要为斑岩型(包括矽卡岩型-斑岩型和斑岩型).     

陕西华县八里坡钼矿床锆石U-Pb和辉钼矿Re-Os年龄及其地质意义

八里坡钼矿是在金堆城钼矿床外围找矿中新发现的斑岩型钼矿床,对其含矿斑岩和矿石进行了成岩成矿年龄精测。采用LA-ICP-MS方法对八里坡斑岩体进行单颗粒锆石U-Pb测年,获得成岩年为155.9±2.3 Ma;采用ICP-MS法测定八里坡钼矿中辉钼矿Re-Os同位素年龄,获得模式年龄为156.3±2.2 Ma;两种方法获得的年龄一致,表明成岩与成矿同时形成。八里坡斑岩体与东秦岭南泥湖、上房沟等斑岩体成岩年龄一致,早于金堆城钼矿床成矿年龄,表明八里坡斑岩体可能是新一期成岩成矿作用,形成于燕山运动的A幕,产出于东亚构造体制转变初期的地球动力学背景,具有重要成岩成矿意义。     

对北洺河铁矿水文地质条件的再认识

通过对北洺河铁矿长期疏干排水条件下,水文地质条件现状的研究,更为准确地指导矿山防治水,并为矿山安全生产提出合理的建议。     

Conditions Of The Present-Day Hydrothermal Metamorphism Of Volcanic Rocks

Hydrothermal metamorphism in volcanic areas causes intense leaching of wall rocks with the development of secondary quartzites and rocks rich in alunite, dickite, and sericite. Three zones of different chemical activity, because of differences in P-T conditions, are evident: 1) zone of liquid hydrotherms (300m – 800m); 2) vaporization zone (10 m – 300m); and 3) condensation zone. Propylitization is common at greatest depth. In the vaporization zone, cooling and increase in pH lead to potassic metasomatism and development of zeolites and orthoclase. Argillization occurs at the surface. The change in the hot waters from acid solutions at depth to alkaline solutions at shallow depths is caused largely by vaporization of dissolved gases such as CO₂ and H₂S at lower pressures. Analyses of the deep circulating thermal waters in the Pauzhetka trough and of altered rocks in the discharge area are given as well as analyses of thermal waters and altered rocks in active volcanoes. Analyses of altered rocks from Wairakei are also compared.- -J. A. Redden.     

Contribution Of Spray Irrigation Of Wastewater To Groundwater Contamination In The Karst Of Southeastern Minnesota,USA

A vegetable- and meat-canning facility located in the karst of southeastern Minnesota disposes ≈2.85×10⁵ m³ yr^?1 of wastewater by spray irrigation of an 83.7-ha field located atop the local groundwater divide. Cannery effluent contains high levels of chloride and nitrogen (organic and ammonia), in excess of 7000 mg/l and 400 mg/l, respectively. Nitrate-nitrogen concentrations are generally < 5 mg/l. Agricultural, domestic, and municipal sources of chloride and nitrate are common in the region, and water supplies frequently exceed the drinking-water limit for nitrate-nitrogen of 10 mg/l. Fifty-two area wells and thirteen surface-water locations were sampled and analyzed for five ionic species, including: chloride (Cl), nitrate-nitrogen (NO₃-N), sulfate (SO₄), nitrite-nitrogen (NO₂-N), and phosphate (PO₄). Two distinct chloride plumes flowing outward from the groundwater divide were identified, and 65% of the wells sampled had nitrate-nitrogen concentrations in excess of 10 mg/l. The data were divided into two groups: one group of samples from wells located near the canning facility and another group from outside that area. A correlation coefficient of R²= 0.004 for Cl vs. NO₃-N in the vicinity of the irrigation fields indicates essentially no relationship between the source of Cl and NO₃. In areas of agricultural and domestic activities located away from the cannery, an R² of 0.54 suggests that Cl and NO₃ have common sources in these areas.     

气化-热液矿床的侧向分带及其成因机制

通过对个旧锡多金属、银山贵金属-多金属、冷水坑银-多金属和东坡钨-锡-多金属矿田的研究,揭示了从下行板块、板片和下盘的不同深度衍生出来的不同的成矿流体,沿着它们上升的通道,在化学、温度和压力上发生有规律的变化,结果导致不同矿物或矿石建造在花岗岩类和有关的主干断裂之间沉淀,并形成侧向分布和侧向分带。     

Some Deep-Seated Features Of Platform Provinces Of The Soviet Union

Geophysical and deep-drilling data disclose the block nature of the faulting in both folded and platform provinces of the crust. System and morphology of deep-seated structures embraces two types of major elements: large angular crustal blocks bordered by intense crush zones on one or more sides,and narrow elongated graben rifts. On platforms, the sedimentary cover conceals the true identity of the deep-seated structures which reveal themselves as gentle flexures but seldom by thickening or thinning of the beds as a whole. Deep rifts of the Russian platforms (Russian, Scythian-Turanian, West Siberian, and East Siberian) are interpreted as parts of a planetary system of rifts. Associated with these major features are sub-systems of more localized faults and fold belts. The deep Russian rifts and structures of the platforms are analyzed by depth to basement measurements which collectively show the enormous amount of absolute crustal subsidence even on relatively elevated platforms. Combinations of platform and geosynclinal tectonic provinces are discussed with some interesting variations on the general pattern of geosynclinal evolution. - -B. N. Cooper.     

Hydrogeologic Evaluation Of Fracture Permeability In Crystalline Basement Aquifers Of Uganda

Throughout Africa, many communities rely on fractured crystalline basement rocks of Precambrian age as the primary source of water supply. The hydrogeology of these aquifers is often poorly understood, and boreholes are frequently sited and designed with little appreciation of the local fracture system. This is especially true in Uganda, where the role of fractures in determining well yield and relative importance of deep and shallow fracture zones have been a continous source of debate since a major national well drilling program was initiated over ten years ago. Recent studies in Uganda have attempted to resolve outstanding hydrogeological questions through the implementation of one of the most comprehensive borehole fracture studies ever undertaken in continental Africa. During the study, 233 packer tests were carried out at 22 sites. Six of the sites, together with a further 16, were subjected to constant yield recovery tests. One well was tested before and after the deployment of yield-enhancing hydraulic fracturing techniques to investigate its effectiveness. Study results reveal the presence of an extremely poor aquifer with little transmissive capability. Across the study area, the hydraulic conductivity of the bedrock average <10^-7 m/s; the majority of transmissivity values are less than 1 m²/d. Packer tests show that fractures occur throughout the depth of well, but are usually very few in number and often exhibit a relatively low permeability. Most wells relied on a single permeable zone for most of their water. In approximately half of the boreholes tested, the most permeable zone was found to occur at the top of the uncased section, just below the regolith. No relationship was found between the distribution of boreholes with shallow, intermediate or deep, high yielding fracture zones and physiographic features. Neither was any relationship observed between hydraulic conductivity and depth within the upper 60 meters of rock tested. Notably, however, no fracture zones more permeable than 10^-5 m/s were found below a depth 57m, and it is suggested that a depth of approximately 60m below ground level may represent the effective base of aquifer. Packer tests performed in a hydraulically fractured borehole confirmed increases in borehole transmissivity by a factor of about 3. The tests were also able to show where improvement in hydraulic conductivity was being achieved. Résumé. Estimation de la perméabilité de fractures dans les aquifères du socle cristallin en Ouganda. Partout en Afrique, les ressources en eau de nombreuses communautés proviennent pour l'essentiel des roches cristallines fracturées d'âge précambrien. L'hydrogéologie de ces aquifères est souvent mal connue; fréquemment, l'implantation des forages s'appuie sur une connaissance bien faible du dispositif local de fracturation. C'est particulièrement vrai en Ouganda, où le rôle de la fracturation dans la détermination du débit des puits et l'importance relative des zones de fractures superficielle et profonde sont le sujet de discussions permanentes depuis le lancement, il y a 10 ans, du programme de forages. Les études récentes en Ouganda ont tenté de répondre aux principales questions concernant l'hydrogéologie en réalisant l'une des études les plus complètes sur la fracturation dans les forages jamais entreprises en Afrique centrale. Cette étude s'appuie sur 233 tests avec packer menés sur 22 sites. Six de ces sites, puis 16 autres ont été soumis à des tests de rabattement à débit constant, puis à l'étude de la remontée. Un puits a été testé avant et après un développement par fracturation hydraulique pour déterminer l'efficacité de la méthode. Les résultats obtenus montrent l'existence d'un aquifère très rédiut à faible transmissivité. Dans la région étudiée, la conductivité hydraulique du socle est en moyenne infériur à 10^щ m/s; la majorité des valeurs de transmissivité sont inférieures à 1 m²/j. Les tests avec packers montrent que les fractures sont présentes tout au long du puits, mais qu'elles sont en général très peu nombreuses et présentent une faible perméabilité. L'essentiel de la ressource de la plupart des puits provient d'une zone perméable unique. Dans près de la moitié des puits testés, la zone la plus perméable a été recoupée au sommet de la partie non tubée, juste sous le régolite. Il n'existe aucune relation entre la physiographie et la répartition des puits selon la position superficielle, intermédiaire ou profonde des fractures productrices. Il n'a pas été non plus observé de relation entre la conductivité hydraulique et la profondeur, dans la tranche de roche testée des 60 m supérieurs. Toutefois, aucune zone fracturée présentant une perméabilité meilleure que 10^ч m/s n'a été trouvée au-dessous de 57 m, ce qui permet de supposer que la base réelle de l'aquifère est à environ 60 m sous la surface du sol. Les tests avec packers effectués dans le forage développé par fracturation hydraulique montrent une amélioration de la transmissivité d'un facteur 3. Les tests ont aussi montré où s'était produite l'amélioration de la conductivité hydraulique.     

我国主要汞矿床的辰砂硫同位素组成

汞矿是我国重要有色金属矿产之一,和世界相比,有其独特之处。据26个汞矿床(点)229件辰砂硫同位素测定值统计,绝大部分辰砂的δ~(34)S都是正值,且与含矿地层中硫酸盐δ~((?)4)S的差值,大致有一个确定的变化范围。辰砂的δ~(34)S比含矿地层中硫酸盐的δ~(34)S平均低9.35‰。从时间的总体上看,各时代地层中辰砂的δ~(34)S变化曲线与海洋硫酸盐的δ~(34)S时间变化曲线,几乎具有相同的演化趋势。因而,在一般情况下,辰砂中的硫都是来自含矿地层中的海洋硫酸盐。     

秦岭凤太矿田层控铅锌(铜)矿床的氧化硅产出特征及其硅质来源

秦岭凤太矿田的所有铅锌(铜)矿床中都含有大量的氧化硅，前人资料中往往以沉积或蚀变单一形成方式论其成因，非此即彼。本文提出氧化硅有三种产出类型，以同生沉积型为主，其次为成岩后生阶段交代灰岩者，第三类为造山期形成的脉体。三类氧化硅的产出特征有许多不同，但硅质来源一致，即均来自深部地层和岩石中循环的含矿热液。对矿床中氧化硅的研究不仅有助于深入探讨矿床的成因，而且对于该类矿床的勘查有较重要的意义。     

沉积矿床成因亚类的划分及沉积菱铁矿的成因

沉积矿床的形成过程,可明确地划分为同生作用、成岩作用与后生作用等三个矿化阶段。现在所见到的沉积矿床,主要是最后矿化阶段改造的结果。根据沉积矿床所经历矿化阶段的不同和表现强度的不同,作者将沉积矿床划分为四种成因亚类:(1)沉积同生矿床;(2)沉积成岩矿床;(3)沉积成岩-后生矿床;(4)沉积后生矿床。产于沉积岩和沉积矿床中的青灰色微细均粒菱铁矿系成岩作用形成,米黄色或淡黄色的粗至巨粒的成分较纯的菱铁矿系后生作用形成。它们都不是同生作用形成的。