湘西合仁坪金矿床硫、铅同位素地球化学

湘西柳林汊一带广泛分布钠长石_石英脉型金矿,合仁坪金矿床是其典型代表。文章对合仁坪金矿床的硫、铅同位素进行了研究,并与区域石英脉型金矿床进行对比,探讨了该矿的成矿物质来源,并初步确定了其矿床成因。研究表明,合仁坪金矿床硫化物的δ34S值范围较窄(-4.8‰~4.4‰),平均为-0.6‰,该矿床的硫为深源硫,由深部变质流体带入;铅的同位素组成较均一,并表现出明显的造山带铅的特点。结合区域成矿作用,进一步研究揭示,合仁坪金矿床为一典型的造山型金矿,其成矿可能与湘西雪峰山地区加里东期的造山作用有关。     

Fluid evolution in the Rushan lode gold deposit of Jiaodong Peninsula, eastern China

The Rushan gold deposit in the Jiaodong Peninsula is currently the largest lode gold in China. Gold occurs mainly in pyrite- and polymetallic sulfide–quartz vein/veinlet stockworks. Fluid inclusions in the deposit are divided into three main types, namely CO₂–H₂O, H₂O–CO₂ ± CH₄ and aqueous ones. Microthermometric data show that the pre-gold fluids were CO₂-dominant (X_CO2 up to 0.53), and the total homogenization temperatures fall in the range of 298377 °C. These fluids, modified by fluid/wallrock reactions, gradually evolved into fluids with less CO₂ (X_CO2 = 0.010.19) in the main ore-forming stage, and the total homogenization temperatures range from 170 to 324 °C. Hydrogen and oxygen stable isotope data suggest that ore-forming fluids were mixture of magmatic and meteoritic origin. Co-occurrence of gold and sulfides implies that gold was most likely transported in the form of gold–sulfide complexes. The wide distribution of CO₂ inclusions means that the pH variation during gold transportation was controlled by CO₂ buffering.     

重新认识和划分矿床类型——隐伏岩金矿体定位预测的一个重要前提

目前流行的岩金矿床分类方案是依据地表已遭受一定剥蚀的矿床地质特征和成因理论而建立的 ,为了有效地开展隐伏岩金矿体定位预测工作 ,必需重新认识和划分矿床类型 ,弄清哪些特征真正具有可比性。文中分析了现有分类方案中几个亟待解决的问题 ,结合金矿的“特殊性” ,提出应简化矿床类型、将成矿区带作为分类的目标 ,将成矿系统作为分类的基础。     

乌拉山岩金矿田微斜长石成因成矿信息研究及其意义

乌拉山含金矿脉赋存于新太古代乌拉山群高级变质岩区（变质程度以角闪岩为主，可达麻粒岩相），受控于乌拉山断裂构造带。区内出露了大桦背花岗岩体以及大量不同成因的长英质体，含金矿脉主要由中等一最大微斜长石，石英，黄铁矿和微晶自然金等矿物组成。对矿脉微斜长石有关信息作了Ｉ值信息量，对应－聚类及成因判别的分析，研究表明成矿作用可分为两个阶段，矿脉系岩浆热液成因。矿脉微斜长石钾长石组分的摩尔分数，有序度（Ｚ）和     

太古代脉状金矿研究的某些新进展

主要介绍了近几年来关于太古代脉状金矿的产出环境、成矿物理化学条件等方面研究取得的一些新进展，加会聚构造成矿和地壳连续成矿模式的提出等；初步讨论了我国在太古代高级变质区寻找高温脉状金矿时应注意的问题。     

胶东脉型金矿成矿深度与矿体延深的模型研究

主体与岩浆成矿热液有关的、产于矿脉中的金矿体,称脉型金矿。本文以成矿深度作为脉型金矿的分类依据,胶东地区可分为中深和浅成两类脉型金矿。从成矿深度模型中,获得中深脉型金矿成矿深度的理论值主要为２．４６～３．８ｋｍ,浅成的为０．２２～２．４９ｋｍ。从矿体延深模型中,获得中深脉型金矿的延深理论值主要为０．４０２～１．００２ｋｍ,浅成的为０．１６４～０．５５８ｋｍ。论述了成矿深度与矿体延深模型的理论值为正相关,说明成矿深度的研究有重要意义。     

高密度电阻率法在东安岩金矿床勘探中的应用

利用高密度电阻率法对东安岩金矿床地表覆盖层下的矿体进行了测量，着重阐述了该方法在确定浅层覆盖、陡立、大脉状金矿体产状的技术手段。认为在该矿区矿体勘探阶段应用高密度电阻率测量方法探寻矿体，具有效率高，成本低的特点。     

平面应变条件下M-C材料屈服时的中主应力公式

基于Mohr-Coulomb准则,通过引入罗德角参数及Mohr-Coulomb准则平面应变等效广义Mises准则,推导了平面应变条件下材料屈服时的中主应力公式,并给出其与基于SMP准则（Spatial Mobiliaztion Piane）的平面应变中主应力公式之间的关系式。对平面应变条件下的条形地基进行了有限元数值模拟,计算结果验证了所推导的平面应变条件下M-C材料屈服时的中主应力公式的正确性,其公式为岩土体的强度和变形分析、中主应力的强度效应的进一步研究,以及Mohr-Coulomb准则的修正提供了有力的基础。     

平行矿体投影方法在矿体空间特征研究中的应用——以小秦岭地区60号金矿脉为例

脉状金矿为非水平或非垂直(即倾斜,尤其是中度倾斜)状态时,垂直或水平投影均会产生较大的投影畸变,导致矿体的几何形态失真和矿体间的展布规律不明显.对产状相对稳定的脉状金矿建立以平均倾向和平均倾角为参数的平行矿体的投影面,借助这个投影面研究金矿体的空间特征和矿脉顶板构造面的起伏规律,实例说明平行矿体的投影方法与常规投影方法...     

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.