The Ore-forming Fluid of the Gold Deposits of Muru Gold Belt in Eastern Shandong, China - a Case Study of Denggezhuang Gold Deposit

Abstract. Denggezhuang gold deposit is an epithermal gold‐quartz vein deposit in northern Muru gold belt, eastern Shandong, China. The deposit occurs in the NNE‐striking faults within the Mesozoic granite. The deposit consists of four major veins with a general NNE‐strike. Based on crosscutting relationships and mineral parageneses, the veins appear to have been formed during the same mineralization epochs, and are further divided into three stages: (1) massive barren quartz veins; (2) quartz‐sulfides veins; (3) late, pure quartz or calcite veinlets. Most gold mineralization is associated with the second stage. The early stage is characterized by quartz, and small amounts of ore minerals (pyrite), the second stage is characterized by large amounts of ore minerals. Fluid inclusions in vein quartz contain C‐H‐O fluids of variable compositions. Three main types of fluid inclusions are recognized at room temperature: type I, two‐phase, aqueous vapor and an aqueous liquid phase (L+V); type II, aqueous‐carbonic inclusions, a CC₂‐liquid with/without vapor and aqueous liquid (LCO₂+VCC₂+Laq.); type III, mono‐phase aqueous liquid (Laq.). Data from fluid inclusion distribution, microthermometry, and gas analysis indicate that fluids associated with Au mineralized quartz veins (stage 2) have moderate salinity ranging from 1.91 to 16.43 wt% NaCl equivalent (modeled salinity around 8–10 wt% NaCl equiv.). These veins formatted at temperatures from 80d? to 280d?C. Fluids associated with barren quartz veins (stage 3) have a low salinity of about 1.91 to 2.57 wt% NaCl equivalent and lower temperature. There is evidence of fluid immiscibility and boiling in ore‐forming stages. Stable isotope analyses of quartz indicate that the veins were deposited by waters with δ^O and δD values ranging from those of magmatic water to typical meteoric water. The gold metallogenesis of Muru gold belt has no relationship with the granite, and formed during the late stage of the crust thinning of North China.     

新疆东准噶尔绿源金矿床成因研究：流体包裹体及氢、氧同位素制约

东准噶尔绿源金矿是近年来新发现的矿床,位于野马泉-琼河坝古生代岛弧带东段的琼河坝矿集区。矿体主要产于上石炭统巴塔玛依内山组中酸性火山岩中,呈似层状、条带状、透镜状,多受断裂构造控制。流体成矿作用可分为4个阶段:石英-黄铁矿阶段、石英(玉髓)-金-黄铁矿阶段、石英-金-多金属硫化物阶段、石英-碳酸盐阶段,其中阶段2和阶段3为金主要成矿阶段。金属硫化物组合主要为黄铁矿-毒砂-闪锌矿-黄铜矿±银金矿组合。文章从流体包裹体和H、O同位素研究入手,对该矿床成矿流体和矿床成因进行探讨。流体包裹体岩相学特征显示,本矿床热液矿物中流体包裹体存在3种类型:富液相气液两相水溶液包裹体(V+L型)、富气相气液两相水溶液包裹体(V型)和纯液相水溶液包裹体(L型)。其中,V+L型包裹体数量最多,各阶段热液矿物中均有发育;V型包裹体数量最少;L型包裹体数量较少。显微测温结果显示:绿源金矿床石英中流体包裹体均一温度介于115~349℃之间,盐度集中于0.7%~8.8%NaCl eqv.之间,密度介于0.66~0.98g/cm~3之间;从阶段2至阶段4,流体均一温度从268~322℃,经181~300℃,降为115~176℃。这些都表明绿源金矿床成矿流体具有低温、低盐度、低密度的特征,与典型浅成低温热液型金矿成矿流体特征相似。对成矿压力和深度的估算表明,其成矿压力为(73~335)×10~5Pa(均值203×10~5Pa),成矿深度为0.24~1.12km(均值0.68km),显示出浅成热液矿床的特征。流体包裹体激光拉曼探针分析显示,各阶段包裹体成分类似,气相成分和液相成分主要为H_2O。成矿流体氢、氧同位素组成分别为δD_(H_2O)=-108.8‰~-129.0‰、δ~(18) O_(H_2O)=-7.2‰~4.6‰,表明成矿流体具有多来源,以大气降水为主的特征。综合矿床地质特征和成矿流体研究,认为流体不混溶作用可能是绿源金矿床的重要成矿机制,该矿床应属浅成低温热液型金矿床。     

Gold Grade and Tonnage Models of the Gold Deposits, China

Abstract: The gold grade and tonnage modelling is applied to some types of the gold deposits in China, including placer, Archaean lode, slate belt, Carlin, volcanogenic, skarn and Shandong Peninsula, among others. The Shandong Peninsula type denotes the gold deposit, which was formed in an intensely reshaped Archaean greenstone belt. The modelling results show: (1) the Archaean lode gold deposits of China are similar to the Homestake type in gold grades. (2) The Chinese slate belt type gold deposits are marked by moderately lower gold grades but considerably larger ore volumes than the similar type elsewhere. (3) The Carlin style gold deposits of China are identified by higher Au grades but evidently smaller sizes in comparison with their counterparts in western North America. (4) The volcanogenic (continental) style is similar to Sado epithermal veins in gold grade‐tonnage models and general characteristics while volcanogenic gold deposits of the oceanic subgroup contrast with Kuroko‐type deposits in the gold grade model. But the Chinese volcanogenic (oceanic) subtype (Palaeozoic age) shows similar higher gold grades to those of the Palaeozoic Kuroko‐type deposits elsewhere. (5) Porphyry and skarn gold deposits tend to have a large size but low grade. (6) Less than half of the Shandong Peninsula gold deposits are of ore volumes exceeding the 50th intercept of the relevant gold tonnage model, implying possible undiscovered gold deposits with a larger size in the peninsula. (7) In general, Chinese gold deposits of larger sizes tend to have lower gold grades in relation to gold grade models. (8) Gold grade‐tonnage models can be effectively influenced by how to include or exclude non‐economic gold resources in the modelling. Ore volumes of gold deposits actually to some extent depend on gold grades. Consequently, the way of including or excluding low‐grade values may effect a gold grade‐tonnage model and cause different interpretation of the modelling results. This is particularly true to the gold deposits, which generally show an inverse correlation between gold grade and tonnage.     

新疆东准噶尔绿源金矿床地质特征与金成矿物质来源分析

绿源浅成低温热液型金矿床位于野马泉-琼河坝古生代岛弧带东段的琼河坝矿集区。赋矿地层为一套中酸性火山熔岩夹火山碎屑岩建造。矿体呈似层状、条带状、透镜状,多受断裂构造控制。其热液成矿作用可分为4个阶段:石英-黄铁矿阶段(S1)、石英(玉髓)-金-黄铁矿阶段(S2)、石英-金-多金属硫化物阶段(S3)、石英-碳酸盐阶段(S4)。金主要赋存于S2和S3阶段。本文对该矿床开展S、Pb同位素及硫化物稀土元素研究,拟揭示其成矿物质来源。结果表明,绿源金矿床金属硫化物的硫同位素组成比较稳定,δ34S集中于+0.2‰~+2.8‰,均值为+1.35‰,显示出岩浆硫的组成特征。矿石与围岩中硫化物的硫同位素δ34S值一致,表明硫可能来源于矿区巴塔玛依内山组火山岩地层。S2和S3阶段硫化物的铅同位素~(206)Pb/~(204)Pb=16.457~18.084、~(207)Pb/~(204)Pb=15.267~15.635、208Pb/~(204)Pb=36.472~38.379,另一件长石的Pb铅同位素~(206)Pb/~(204)Pb=18.546、~(207)Pb/~(204)Pb=15.509、208Pb/~(204)Pb=38.183,μ值介于9.11~9.58之间,ω值介于33.97~38.61之间。上述各铅同位素比值变化范围较大,远远大于正常铅同位素组成的变化范围。结合同位素组成特征及特征参数法认为绿源金矿床矿石Pb为异常Pb,铅源为混合来源,一部分来源于上地壳物质,一部分来源于地幔物质。硫化物稀土元素特征与火山岩类似,暗示成矿物质可能来源于火山岩地层。H、O同位素特征显示,绿源金矿成矿流体以大气降水为主,有少量岩浆水的加入。综合S、Pb同位素、稀土元素等分析,本文认为绿源矿区岩浆活动和成矿作用具有壳幔混合源特征,成矿物质具深源特征,主要直接来自赋矿火山岩。     

中国东部中生代浅成热液金矿的类型、特征及其地球动力学背景

中国东部中生代浅成热液金矿可以划分为与花岗岩和与碱性岩有关的两种类型；也可以分为高硫型和低硫型两大类，而且以后一种为主。这些金矿的形成和分布受区域构造制约，具体地说是受破火山口、火山角砾岩筒以及与火山机构有关的断裂控制。成矿围岩为火山岩类及同源花岗质岩石和周围地层。主要的蚀变组合为冰长石一玉髓一绢云母或明矾石一高岭石一石英(玉髓)。成矿年龄分布在180～188Ma，135～144Ma，127～115Ma和94～105Ma四个区间，前三组年龄分别响应于中生代华北板块与扬子克拉通的造山碰撞后陆内造山的伸展过程、构造体制大转折以及岩石圈大减薄，后一组为华南地区岩石圈再一次强烈伸展期间的产物。虽然这些矿床的形成时间有差异，但都是发育于大陆伸展环境中。     

Dating and Fluid Geochemistry of the Sarkobu Gold Deposit in Altay, Xinjiang, China

The dating of fluid inclusions of quartz yields an Ar-Ar isochrone age of 320.4±6 Ma. Three types of fluid inclusions have been identified with the homogenization temperature ranging from 157℃ to 362℃. The homogenization temperature consists of two groups. The first group varies from 157℃ to 166℃, and the second from 232℃ to 362℃. Their chemical composition is dominated by Na+-Ca2+-Mg2+ and Cl-. The relative concentration of ions is characteristic by Na+>Ca2+>K+>Mg2+ and C1->SO42-> F-. The δD and δ18O values indicate that the ore-forming fluid originates from mixing of multi-source water. The Sarkobu gold deposit has experienced two mineralization stages: gold was enriched during the volcanic-exhalative-sedimentary process in the early stage, while the gold deposit was finally formed under compression-shearing during the orogenic period.     

新疆托库孜巴依金矿床地质特征及成因

新疆托库孜巴依金矿床的地质、地球化学特征以及同位素年龄,氢、氧、硫等同位素测试和流体包裹体研究表明,该矿床经历了热液成矿期和地表氧化期2个成矿期,工业矿体主要富集在热液期的金-硫化物-碲化物-石英阶段。含矿石英脉中黄铁矿的δ(34S)值与围岩硫特征基本相符,具上地幔源δ(34S)分布特征。石英中包裹体氢氧同位素组成落于大气降水线之下,在变质水、岩浆水下部边缘,具混源特征。铅同位素组成落在上地幔和造山带增长线之间偏造山带侧。成矿流体气相成分以水为主,CO2、CO成分很少,液相离子成分以Ca2+,Na+,K+,HCO3-,SO24-为主。流体包裹体的盐度为6.00%～9.44%,密度为0.763～0.922g/cm3。均一温度为275～324,207～273,207～218,191～222℃。托库孜巴依金矿床属于韧性剪切带型金矿床。构造变形作用促使流体萃取了阿勒泰组上亚组第二岩性段变质火山岩或火山沉积岩中的成矿元素,导致金元素在有利的空间形成含金石英脉,后期岩浆侵入活动为金的进一步富集提供了热源和流体。     

新疆阿希低硫型金矿床流体地球化学特征与成矿机制

位于新疆西天山的阿希金矿为一赋存于古生代陆相火山岩中的冰长石—绢云母型（低硫型）浅成低温热液金矿床,其围岩为下石炭统安山质火山岩和火山碎屑岩。矿体呈脉状产出,严格受古火山机构外围的环形断裂带控制。成矿作用分为石英—玉髓状石英脉阶段、石英脉阶段、石英碳酸盐脉阶段、硫化物脉阶段、碳酸盐脉阶段,形成的矿石有石英脉型和蚀变岩型两类。成矿作用阶段形成的流体包裹体主要有三类：液相水溶液包裹体、富液相气液两相水溶液包裹体和富气相的气液两相水溶液包裹体,其中以前两类为主。三类流体包裹体在矿石中同时出现,说明它们形成于非均一的流体介质条件,矿床形成时流体发生了沸腾作用。成矿流体冰点温度一般为-0.3--2.3℃,相应盐度为0.48%-3.75%NaCleq,平均1.85%NaCleq;冰点峰值温度位于-0.4--1.6℃,相应盐度为0.66%-2.63%NaCleq。流体包裹体均一温度为121-335℃,平均209℃;均一温度峰值为140-240℃,计算得到流体密度为0.73-0.96,成矿深度小于700m。成矿流体的氢、氧同位素变化范围小,δDSMOW,H2O=-98‰--116‰,δ18OSMOW,H2O=-0.55‰-1.65‰;碳同位素δ13CPDB,方解石=2.6‰-4.9‰,δ34SCDT=-4.0‰-3.1‰,平均值为δ34SCDT=-0.45‰,表明成矿流体主要为循环的大气降水,成矿物质主要来自赋矿围岩火山岩及基底岩石。含金石英脉中冰长石、叶片状石英和硫化物集合体的出现,以及气相比例和均一温度变化很大的液相、富液相和富气相的水溶液包裹体的共生,说明流体的沸腾作用是引起成矿流体中矿质发生沉淀富集的主要成矿机制;对于蚀变岩型矿石,其成矿以水岩交代反应为主,成矿作用过程中流体处于近中性pH值环境。     

新疆北部布尔克斯岱金矿床40Ar-39Ar同位素年代学研究

布尔克斯岱金矿床是新疆北部萨吾尔山东段重要的金矿床之一,对该金矿床成矿阶段两个石英样品进行快中子活化法测年,谱线特征均为马鞍型,其坪年龄分别为(335.5±0.3) Ma、(336.2±0.4) Ma,最小视年龄分别为(334.9±8.3) Ma、(334.6±10.3) Ma,等时线年龄分别为(335.5±1.2) Ma、(336.8±0.5) Ma.坪年龄代表了含金石英脉的形成时代,相当于晚海西期.新疆北部金矿形成可能与碰撞造山作用有关.     

西秦岭地区造山型与卡林型金矿床

西秦岭金矿床分为卡林型和造山型两类。卡林型金矿床麇集于南秦岭和松潘—甘孜造山带的东北部。三叠纪和早侏罗世的同构造花岗闪长岩广泛分布于西秦岭中部和南部、松潘—甘孜盆地以及扬子克拉通边缘。造山型脉状金矿床主要分布于西秦岭造山带中的脆韧性剪切带内。大部分粗粒金主要赋存在网格状石英细脉和角砾状围岩中的黄铁矿、磁黄铁矿、毒砂和少量贱金属硫化物中和以分散状分布在蚀变围岩中。同位素资料表明晚三叠世 -中侏罗世与扬子克拉通俯冲有关的作用控制了造山型金矿床的形成。     

质疑新疆阿希、石英滩浅成低温热液金矿床“高钾”流体

一些文献列举了新疆阿希和石英滩金矿床群体包裹体成分分析结果，其阳离子中Na^ /K^ 比值(原子比)＜l，并存在大量过剩阳离子等与矿床地质特征相悖的特点。文章利用群体包裹体分析方法，对阿希金矿含金石英脉进行了专门的实验，结果证实上述分析结果与分析样品不纯和非包裹体来源的污染有关。文中还讨论了有关包裹体成分分析和结果应用中值得注意的一些问题。     

Geochemistry, Geochronology and Genesis of Gold Mineralization in Nurt of Northern Altay,Xinjiang： A Case Study of the Aketishikan Gold Deposit

Gold deposits such as the Aketishikan, Togetobie, Tasbig-Kokeydlas, Kums and Hongshanzui gold deposits in the Nurt area in Altay of Xinjiang were found in Member 3 rhyolite tufflava, fragmental lava and ignimbrite of the Carboniferous Hongshanzui Group. Trace and rare earth elements, sulfur, lead, oxygen and hydrogen isotopes, and geochronological studies indicate that the ore-forming material was mostly supplied by the Carboniferous volcanic rocks through water-rock interaction under a low-to-moderate temperature, and the hydrothermal ore-forming fluid came from meteoric water with some magmatic water input evolved from the granitic magmas. Gold deposits in the Nurt area as well as in the northern Altay might form in multiple stages, and the Yanshanian mineralization period should be paid more attention besides the Variscan mineralization period.     

Geochemistry, Geochronology and Genesis of Gold Mineralization in Nurt of Northern Altay, Xinjiang: A Case Study on the Aketishikan Gold Deposit

Gold deposits such as the Aketishikan, Togetobie, Tasbig-Kokeydlas, Kums and Hongshanzui gold deposits in the Nurt area in Altay of Xinjiang were found in Member 3 rhyolite tufflava, fragmental lava and ignimbrite of the Carboniferous Hongshanzui Group. Trace and rare earth elements, sulfur, lead, oxygen and hydrogen isotopes, and geochronological studies indicate that the ore-forming material was mostly supplied by the Carboniferous volcanic rocks through water-rock interaction under a low-to-moderate temperature, and the hydrothermal ore-forming fluid came from meteoric water with some magmatic water input evolved from the granitic magmas. Gold deposits in the Nurt area as well as in the northern Altay might form in multiple stages, and the Yanshanian mineralization period should be paid more attention besides the Variscan mineralization period.     

北山中南带海西-印支期岩浆活动与金的成矿作用

北山中南带地处哈萨克斯坦和塔里木板块交汇处,区内深大断裂纵横交错,各类海西期-印支期岩浆岩发育,金矿床(点)星罗棋布,是中国西北地区最重要的金成矿带之一.该区金矿床(点)大体可划分为:①火山岩型;②侵入岩型;③夕卡岩型;④变质岩型;⑤沉积岩型.尽管各类金矿床(点)的容矿围岩不同,但均与海西期或印支期火成岩具密切的时空分布关系.受海西期和印支期各板块空间分布位置、运动机制和构造应力变化的影响,强烈的构造-岩浆活动不仅可形成大面积分布的高钾钙-碱性火成岩,而且导致贵重金属元素"爆发式"堆积.研究结果表明,各金矿床(点)成矿流体大都是深源岩浆流体与大气降水相混合的产物,属混源型中温热液金矿床(点).     

Geology,Pb Isotope Geochemistry and Ore Genesis of the Liziyuan Gold Deposit,West Qinling Orogen,Central China

The Liziyuan gold deposit, situated on the south side of the Shangdan suture zone, West Qinling Orogen, occurs in metamorphic volcanic rocks(greenschist facies) of the early Paleozoic Liziyuan Group and in Indosinian Tianzishan monzogranite. Orebodies in the Liziyuan gold field are controlled by the ductile-brittle shear zone, and by thrusting nappe faults related to the Indosinian orogeny. In detail, this paper analyzed the geological characteristics of the Liziyuan gold field, and the Pb isotopes of the Lziyuan host rocks, granitoids(Tianzishan monzogranite and Jiancaowan syenite porphyry), sulfides, and auriferous quartz veins by multiple-collector inductively coupled plasma mass spectrometry(MC-ICPMS). In addition, previous data on the sulfur, hydrogen, and oxygen isotopes were employed to discuss the possible sources of the ore-forming fluids and materials, and to further understand the tectonic setting of the Liziyuan gold deposit. The sulfides and their host rocks(Lziyuan Group), Tianzishan monzogranite and Jiancaowan syenite porphyry, and auriferous quartz veins have similar Pb isotopic compositions.Zartman's plumbotectonic model diagram shows that most of the data for the deposit fall near the orogenic Pb evolutionary curve or within the area between the orogenic and mantle Pb evolutionary curves. In the△β-△γ diagram, which genetically classifies the lead isotopes, most of the data fall within the range of the subduction-zone lead mixed with upper crust and mantle. This indicates that a complex source of the ore lead formed in the orogenic environment. The δ~(34)S values of the sulfides range from 3.90 to 8.50‰(average6.80‰), with a pronounced mode at 5.00‰-8.00‰. These values are consistent with that of orogenic gold deposits worldwide, indicating that the sulfur sourced mainly from reduced metamorphic fluids. The isotopic hydrogen and oxygen compositions support a predominantly metamorphic origin of the oreforming fluids, with possible mixing of minor magmatic fluids, but the late stage was dominated by meteoric water. The characteristics of the Liziyuan gold deposit formed in the Indosinian orogenic environment of the Qinling Orogen are consistent with those of orogenic gold deposits found worldwide.     

中国卡林型金矿床金的赋存状态研究

卡林型金矿的载金矿物主要为黄铁矿和粘土矿物，其次是毒砂和石英。金主要以包裹金形式存在，秦岭地区存在有单体金。金主要赋存在含砷的铁硫化物相中。氧化矿石以游离金大量出现为特征。     

新疆东天山垅西金矿床地质和地球化学特征

垅西金矿是东天山地区较为典型的石英脉型金矿床，文章对该矿床进行了流体包裹体的温度测定、气液相成分分析、稀土元素分析和氢氧同位素分析。研究结果表明，垅西金矿的成矿温度为222～313℃，成矿深度为2～3．2km，属中成中温热液矿床；流体包裹体中H2O和CO2为主要气相成分，Na^ 、K^ 和Cl^-为主要液相成分，成矿流体主要来自岩浆水，晚期混入少量大气降水；成矿金属物质主要来自下石炭统企鹅山群中基性火山岩。     

南天山萨恨托亥—大山口—带穆龙套型金矿地质及地球化学特征

南天山中段萨恨托亥大山口成矿带内的金矿赋存在浅变质浊积岩系碎屑岩内。本文以该带内2个典型金矿———大山口金矿和萨恨托亥金矿为例,对其成矿特征进行了初步研究。研究表明,金矿体受韧脆性剪切带控制,产状稳定,矿石类型简单,硫化物种类单一且含量较低。成矿可分为糜棱岩阶段和石英脉阶段,与控矿的韧脆性剪切带的发展演化各阶段相对应。成矿发生于中低温条件下弱酸性向中性环境过渡阶段,成矿流体是以深源流体(含岩浆热液)为主的多源混合热液(构造热液)。成矿作用为构造成岩成矿(韧性剪切带成矿),矿床成因类型为(构造)热液型金矿,     

Fluid Geochemistry and Metallogenesis of the Hatu Gold Deposit in the Junggar Basin, Xinjiang

The Hatu large gold deposit is located on the western margin of the Junggar basin, Xinjiang. Its mineralization is characterized by auriferous quartz veins and Au-bearing altered fracturing zones. Studies on mineralogy, inclusions and decrepitation temperature indicate that the gold deposit was formed by overlapping of two kinds of fluid of different origins, instead of gradual evolution of a single fluid. The auriferous quartz veins are related to magmatism-originated fluid, but the Au-bearing altered fracturing zones to deep-derived fluid. Bonanzas in quartz veins were formed and localized at overlapping positions of two types of fluid under intensive compression.     

新疆伽师砂岩型铜矿床地质及S、Pb同位素地球化学

西南天山新生代山前盆地中的伽师铜矿是新疆近年发现和开发的一个重要的砂岩型铜矿,矿体产于古近系灰白色含岩屑钙质细砂岩中,呈与地层整合的板状、层状。矿石中硫化物主要为辉铜矿,矿体深部出现斑铜矿,极少量黄铁矿、闪锌矿等,硫化物多交代砂岩中胶结物或碎屑颗粒形成胶结结构,矿石发育稀疏浸染状、团块状、结核状等多种构造。矿石的硫同位素δ³⁴S_V-CDT在-33.4‰~-24.6‰之间。矿石的铅同位素组成²⁰⁶Pb/²⁰⁴Pb=18.376~18.607、²⁰⁷Pb/²⁰⁴Pb=15.612~15.655、 ²⁰⁸Pb/²⁰⁴Pb=38.475~38.747。铜的硫化物矿化表现为含铜盆地流体(地下水)交代砂岩而沉淀,铜矿体形成于古近系细砂岩成岩晚期,矿石硫来源于细菌还原硫酸盐,矿石铅同位素组成指示成矿金属元素来自沉积盆地周围的蚀源区。