东秦岭上宫金矿流体成矿作用:矿物学研究

通过对上宫金矿矿物学资料的研究，确定其成矿过程具有3阶段演化特征。早阶段以粗粒乳白色石英脉为标志，矿物破碎、变形明显，金和杂质成分含量低，形成于挤压构造背景下静岩压力的变质流体。中阶段发育细粒多金属硫化物-碲化物-自然元素组合，呈微细网脉浸染于共轭节理或裂隙，没有遭受变形，金和杂质成分含量高，自然金与其他矿物属共沉淀关系，由变质流体沸腾导致，而流体沸腾则由造山过程的地壳快速隆升剥蚀引起。晚阶段发育具梳状构造的石英-碳酸盐网脉，含金性较低，由静水压力的大气降水热液在伸展构造背景下贯入张性裂隙形成。矿床地质地球化学特征与造山型金矿一致，成矿过程同步于陆陆碰撞造山作用，属于典型的断控脉状造山型金矿，成因适合于CMF模式。     

熊耳山上宫金矿稀土元素特征及对金矿物质来源的指示意义

上宫金矿矿化样品与熊耳群安山岩、燕山期花岗岩有着相似的稀土元素特征, 其物源关系更为密切。不同类型矿石的稀土总质量分数存在较大差别, 总体呈现出矿化程度越强稀土总量越低的特征。大部分金矿石与铅锌(银金)矿石均表现出弱的Eu、Ce异常, 其中δEu金矿石(均值0.84)＞δEu铅锌矿石(均值0.75), δCe金矿石(均值0.88)＞δCe铅锌矿石(均值0.96), 造成这种现象的原因可能是热液交代或成矿热液为富Cl–的还原性流体。 (Sm/Eu)样品/(Sm/Eu)球粒陨石-(Sm/Eu)样品图解显示, 上宫金矿各类样品能近似拟合成一条直线, 说明了岩浆热液为成矿提供了最初的热源和物源, 而安山岩和片麻岩的接触交代可能对成矿提供了部分物源。矿石样品和蚀变岩样品中均出现不同程度的Tb、Tm元素正异常, 说明成矿物质来源可能受到了地壳岩石的影响。上宫金矿田δEu-Au相关图解显示, 成矿过程中, 随着Au元素的富集, Eu元素也出现相对富集。     

The Shanggong gold deposit, Eastern Qinling Orogen, China: Isotope geochemistry and implications for ore genesis

The Shanggong Au deposit in the Xiong’er Terrane, East Qinling, China, has resources of about 30 ton Au, making it one of the largest orogenic-mesothermal Au deposits hosted in volcanic rocks of the Mesoproterozoic Xiong’er Group. Three stages of hydrothermal activity are recognized (early, middle and late), of which two (early and middle) were ore producing and characterized by quartz–pyrite and polymetallic sulfides, respectively. The third and late stage is represented by a carbonate–quartz assemblage. Hydrogen, oxygen and carbon isotope systematics of the Shanggong deposit from a previous work suggest that the early stage fluids were derived from magmatic and/or metamorphic devolatilization of sedimentary rocks at depth. This is supported by new C, S and published Sr and Pb isotopic data, presented in this paper. These new data, δ¹³C values ranging from 1.5 ‰ for early stage ankerite to −2.2 ‰ for late stage ankerite, negative δ³⁴S values for sulfides from the middle stage (–19.2 to –6.3 ‰), suggest a contribution from organic matter and that the ore fluid evolved from deeply sourced to shallowly sourced, with those of the middle stage representing a mixture of these two fluid systems. The comparison of the hydrogen–oxygen–carbon–sulfur–lead–strontium isotope systematics between the Shanggong deposit and the main lithologies in the Xiong’er Terrane, shows that neither these nor the underlying lower crust and mantle, or combinations thereof, could be considered as the source of ore fluids for the Shanggong Au deposit. A likely source was a carbonaceous carbonate, sandstone, shale, chert sequence in the underthrusted Guandaokou and Luanchuan Groups, exposed south of the Xiong’er Terrane.Ar–Ar and Rb–Sr isochron ages for mineral phases of the early, middle and late stages, together with geological field data, constrain the timing of the hydrothermal activity and Au metallogenesis at 242 ± 10, 167 ± 7 and 112 ± 7 Ma, respectively. This metallogenesis and associated granitic magmatism, can be related to the continental collision between the Yangtze and North China Cratons that resulted in the formation of the Qinling Orogen, led to the different hydrothermal systems that were responsible for the three stages that formed the Shanggong Au deposit, over a period of about 130 Myrs.     

东秦岭上宫金矿流体成矿作用:放射成因同位素地球化学研究

赋存于东秦岭熊耳地体熊耳群陆相火山岩中的上宫金矿,是典型的断控脉状造山型金矿床,其成矿物质长期被认为来自结晶基底太华超群(所谓原生矿源层)、盖层熊耳群(所谓衍生矿源层)或燕山期花岗岩,或者下伏地壳或地幔。但是,这些观点与放射成因同位素研究结果相矛盾,因此可以认为成矿物质侧向来源于熊耳地体以南的管道口群栾川群沉积地层,后者沿马超营断裂向北陆内俯冲到熊耳地体之下,通过变质脱水导致上宫金矿成矿流体系统的发育和矿床形成。此外,成矿早阶段石英40Ar/39Ar年龄为222.8Ma±24.9Ma;成矿早、中、晚阶段矿物或岩石的Rb-Sr等时线年龄分别为242Ma±10Ma,165Ma±7Ma和113Ma±6Ma,表明成矿发生在250Ma～100Ma之间,同步于华北与扬子板块的陆陆碰撞造山作用。     

豫西上宫构造蚀变岩型金矿成矿过程中的流体—岩石反应

上宫金矿赋存在中元古界熊耳群安山岩和玄武岩中,矿体受断裂破碎带控制。含矿热液在迁移过程中,与围岩发生了强烈的流体－岩石反应,造成Ａｕ、Ａｇ、Ａｓ、Ｓｂ等成矿及其相关微量元素和Ａｌ２Ｏ３、ＴｉＯ２、Ｎａ２Ｏ等常量元素含量增加,稀土元素及其总量急剧减少。流体－岩石反应第一阶段发生的温度和压力条件为３６５℃～３００℃和２８５～２００ＭＰａ,而大量金沉淀成矿时的温度和压力范围则分别为３２５℃～２４０℃和１６０～１００ＭＰａ。成矿热液类型及其演化比较简单,从初始的低盐度（９．５％～６．３％ＮａＣｌ）、ＸＣＯ２为０．１８～０．２４的含ＣＯ２流体演化为低盐度（５．９％～１．６％ＮａＣｌ）的水溶液流体。流体－岩石反应是造成上宫金矿金沉淀成矿最主要的原因     

河南省洛宁上宫金矿复杂地层钻探施工技术

河南省洛宁上宫金矿区地质条件复杂,地层破碎,特别是中下部蚀变绿泥石化严重,遇水分散剥落坍塌,易造成下钻困难、埋钻等事故,施工难度大。针对矿区地层特点,从设备材料选型、钻孔结构、钻头选用等方面采取措施,重点应用成膜冲洗液解决蚀变破碎绿泥石化地层孔壁失稳取心钻进困难问题,取得了显著效果,为今后复杂地层施工积累了一定的经验。     

东秦岭上宫金矿成矿流体与成矿物质来源新认识

上宫金矿床位于华北克拉通南缘的熊耳地体之中,是典型的构造蚀变岩型金矿.本文对上宫金矿的同位素地球化学资料进行了系统分析和综合研究,对其成矿物质和成矿流体的来源取得了一些新的认识.氢-氧-碳同位素体系研究表明,成矿流体并非来自燕山期岩浆热液,也不是来自于太华群或者官道口群和栾川群的变质脱水作用,而主要来自深部地幔或者由幔源岩浆派生,并在成矿的过程中逐渐向大气降水演化.硫-铅-锶同位素体系指示成矿物质为壳幔混合来源,地幔和太华群可能均提供了部分成矿物质.印支期华北与扬子板块发生碰撞对接时导致了强烈的壳幔相互作用,并驱动深部流体向上运移,上官金矿正是在这种构造背景下形成的.