Isotope geochemistry of the Tieluping silver-lead deposit, Henan, China: A case study of orogenic silver-dominated deposits and related tectonic setting

The Tieluping silver deposit, which is sited along NE-trending faults within the high-grade metamorphic basement of the Xionger Terrane in the Qinling orogenic belt, is part of an important, recently discovered Mesozoic orogenic-type Ag-Pb belt. Ore formation includes three stages: an early barren quartz-pyrite stage (E), an intermediate polymetallic sulfide ore stage (M), and a late barren carbonate stage (L). Carbon, sulfur and lead isotope systematics indicate that the E-stage fluids are deeply sourced; the L-stage fluids are shallow-sourced meteoric water; whereas the M-stage fluids are a mix of deep-sourced and shallow-sourced fluids. Sulfur and lead isotope data show that the ore-forming fluids must have originated from a source with elevated radiogenic lead and low ³⁴S values, that differs significantly from exposed geologic units in the Xionger Terrane, the lower crust and the mantle. This supports the view that the carbonate-shale-chert sequences of the Guandaokou and Luanchuan Groups south of the Machaoying fault might be the favorable sources, although little is known about their isotopic compositions. A tectonic model that combines collisional orogeny, metallogeny and hydrothermal fluid flow is proposed to explain the formation of the Tieluping silver deposit. During the Mesozoic collision between the North China Craton and South China Block (Early-Mid Triassic Indosinian Orogeny), crustal slabs containing the carbonate-shale-chert sequences of the Guandaokou and Luanchuan Groups, locally rich in organic matter (carbonaceous shale), were thrust northwards beneath the Xionger Terrane along the Machaoying fault. Metamorphic devolatilisation of this underthrust slab probably provided the ore-forming fluids to develop the Ag-Pb ore belt, which includes the Tieluping silver deposit. Fluids and magmas were emplaced during extensional stages related to the Jurassic-Cretaceous Yanshanian Orogeny.Editorial Handling: B. Lehmann     

广东省银矿成矿地质条件研究

通过对广东省银矿床的成矿大地构造环境以及矿床形成的“层”、“体”、“位”条件的综合分析认为：在银矿床形成过程中,构造位及矿源体对银矿床起着重要的控制作用。统计资料表明,产于不同规模的断裂破碎带中的银矿床(点)占矿床(点)总数的65．7％,而与火成岩体有关的银矿床(点)占总数的84．8％;银矿床的最佳成矿地质条件为有利的“层”、“体”、“位”复合部位。     

大宁岩体的基本特征及其与成矿作用的关系

大宁岩体由二长花岗岩、花岗闪长岩及石英二长闪长岩组成,侵入时代为晚志留世(K—A r法407、445M a)。通过对岩体的微量元素、稀土元素及硫、铅、氧等同位素研究,认为银、金矿的成矿物质来自深源岩浆,大量的暗色包体是主要的成矿物质之一,在深大断裂的切割影响下,经多次构造活动,使得不同阶段的成矿物质富集并叠加而形成矿体。最利于A u、A g成矿的部位是花岗闪长岩与石英二长闪长岩的接触界线附近以及花岗闪长岩与围岩接触带附近的断裂交汇处。     

新疆伊犁晚古生代裂谷陆相火山岩型铜(银)矿的成矿规律及其找矿前景--以阿吾拉勒地区为例

伊犁晚古生代裂谷陆相火山岩型铜银矿产于碱性火山岩中,在区域上表现出层控特点,即沿着上、下二叠统过渡界面分布,且多产于火山旋回顶部层位,明显受火山穹隆、火山洼地和火山机构及其派生构造的控制。具有准斑岩型、火山沉积型、火山热液型配套的矿床类型。多以火山构造为成矿基础而构成铜银成矿集中区。其中,托斯巴火山穹隆区、阿克吐别克火山向斜区和特提达坂火山穹隆区的多矿点火山构造类型区具有最佳的找矿前景。     

大青山东段九龙湾银-多金属矿床的次火山热液成因——流体包裹体证据

九龙湾银矿床位于内蒙古大青山东段，是近年来发现的有潜力的银多金属矿床。流体包裹体的岩相学、显微测温、激光拉曼探针及扫描电钐能谱分析研究表明，主成矿阶段的成矿流体以中低温（150-310℃）、中低盐度（3-17wt％NaCl）、较低密度（0．75～1．0g／cm^3）的盐水体系为特征，与造山型金矿床的富CO2流体有很大的差别。蚀变硅化阶段的流体相对富CO2、CH4、N2等挥发分，但在银铅锌主成矿阶段演化成贫CO2的盐水流体。九龙湾成矿流体的这种性质与国内外陆相火山一次火山热液型银矿床的成矿流体特征非常相似。矿床地质特征（与石英斑岩的关系、断裂控矿、围岩蚀变、矿石矿物共生组合）、稳定同位素地球化学特征均说明九龙湾银-多金属矿床应属与陆相次火山岩有关的中低温浅成热液矿床。     

岩浆岩型伴生金矿床的时空分布特征及区域控矿作用

从伴生金的角度对岩浆岩型矿床的时空分布特征及区域控矿作用进行了总结：划分了吉中、北阴山、富蕴、金川、玛沁、略阳、康滇、哀牢山八个成矿带;指出岩浆岩型伴生金矿床最主要的成矿期为元古代和晚古生代;强调台褶过渡区及褶皱过渡区、深大断裂、基性超基性岩的区域控矿作用。     

云南拱丁金矿中富银黄铜矿的初步研究

富银黄铜矿发现于云南省沧源佤族自治县斑洪乡拱丁金矿石英脉内,该矿是以金(银)为主的多金属硫化物矿床。共生矿物有自然金、银金矿、自然银、银黝铜矿及辉锑铅银矿等。     

双波长分光光度法测定微量银的研究

本文用双波长分光光度法研究了Ag-5-Br-PADAP-柠檬酸-十二烷基硫酸钠多元显示体系。实验表明,该体系的显色适宜酸度为pH5.5,测量波长为532nm,参比波长为356nm。表观摩尔吸光系数为1.26×10~5l·mol~(-1)·cm~(-1),灵敏度比单波长提高近两倍。银量在0～20μg/25ml内符合比耳定律。方法简便快速,灵敏度高,适用于地质样品中微量银的测定。     

Geochemical and mineralogical anomalies of the late Permian coal in the Zhijin coalfield of southwest China and their volcanic origin

This paper describes the influence of volcanic ash on the concentrations and occurrences of associated elements in coal in the Zhijin Coalfield in western Guizhou Province, China. Our studies reveal that the No. 9 coal seam in the Zhijin Coalfield has very high content of Fe (4.34%), Cu (369.90 μg/g), U (49.6 μg/g), Mo (63.10 μg/g), Zn (33.97 μg/g), and Zr (841.80 μg/g). The studies have also found that elements, such as Fe and Cu, do not occur as sulfides in this coal seam, in sharp contrast to many other coal seams in China. The geochemical and mineralogical anomalies of the coal seam are attributed to synsedimentary volcanic ash. In addition to normal macerals and minerals in coal, a volcanic-influenced material (VIM) derived from volcanic ash, detrital material of terrigenous origin and organic matter was identified under polarized-light reflectance microscopy and scanning electron microscopy equipped with energy-dispersive X-ray (EDX) analyzer. The volcanic-influenced material is the main carrier of the above elements in this coal. Six types of the volcanic-influenced material (VIM-1, VIM-2, VIM-3, VIM-4, VIM-5, and VIM-6) are further distinguished on the basis of their structures and compositions. To the best of our knowledge, this is the first report that presents a detailed classification of coal components with a high content of volcanic ash.     

新桥硫铁矿伴生金银赋存状态及分布规律

系统阐述了新桥矿伴生金银的赋存状态和分布规律 ,对综合利用矿产资源 ,提高金银的回收率 ,以及深部资源预测、外围找矿均具有一定的指导意义