METALLOGENIC CONDITIONS OF GOLD-BEARING SKARN DEPOSITS ALONG THE MIDDLE-LOW ER REACHES OF THE YANGTZE RIVER

ＭＥＴＡＬＬＯＧＥＮＩＣＣＯＮＤＩＴＩＯＮＳＯＦＧＯＬＤ－ＢＥＡＲＩＮＧＳＫＡＲＮＤＥＰＯＳＩＴＳＡＬＯＮＧＴＨＥＭＩＤＤＬＥ－ＬＯＷＥＲＲＥＡＣＨＥＳＯＦＴＨＥＹＡＮＧＴＺＥＲＩＶＥＲＺｈａｎｇＳｈｕｇｅｎＷａｎｇＤａｗｅｉ（Ｄｅｐａｒｔｍｅｎｔｏ...

Origin of Gold-Bearing Fluid and Its Initiative Localization Mechanism in Xiadian Gold Deposit,Shandong Province

The composition of quartz inclusions and trace elements in ore indicate that gold\|bearing fluid in the Xiadian gold deposit, Shandong Province, stemmed from both mantle and magma, belonging to a composite origin. Based on theoretical analysis and high temperature and high pressure experimental studies, gold\|bearing fluid initiative localization mechanism and the forming environment of ore\|host rocks are discussed in the present paper. The composite fluid extracted gold from rocks because of its expanding and injecting forces and flew through ore\|conducive structures, leading to the breakup of rocks. The generation of ore\|host faults and the precipitation of gold\|bearing fluid occurred almost simultaneously. This study provides further information about the relationships between gold ore veins and basic\|ultrabasic vein rocks and intermediate vein rocks, the spatial distribution of gold ore veins and the rules governing the migration of ore fluids.

Rb-Sr Isotopic Chronology of the Au-Bearing Quartz Veins in Gold Deposits in the Eastern Part of North China Platform

In the eastern part of China there had occurred large\|scale gold mineralization during the Mesozoic, resulting in a large number of important gold ore\|concentrated areas. In this paper we have selected some isotope data (including four gold deposits previously studied and two gold deposits in this work) of Au\|bearing quartz veins of the representative gold deposits in six important gold ore\|concentrated areas in the periphery of the North China Platform and calculated their metallogenic ages using the method of Ludwig (2.90 version). The results show that the representative gold deposits in the six gold ore\|concentrated areas were formed during the Mesozoic.

Chronology and Crust-Mantle Mixing of Ore-forming Porphyry of the Bangongco: Evidence from Zircon U-Pb Age and Hf Isotopes of the Naruo Porphyry Copper-Gold Deposit

The Naruo porphyry copper-gold deposit （hereinafter referred to as the Naruo deposit） in Tibet is a potentially ultra-large, typical gold-rich porphyry copper deposit, which was recently discovered in the Bangongco-Nujiang metallogenic belt. This study analyzed U-Ph chronology and Hf isotopes of the ore-bearing granodiorite porphyry in the Naruo deposit using the LA-ICPMS dating technique. The results show that the weighted average age is 124.03±0.94Ma （MSWD=1.7, n=20）, and 2±6pb/23SU isocbron age is 126.2±2.7 Ma （MSWD=1.02, n=20）, both of which are within the error. The weighted average age represents the crystallization age of the granodiorite porphyry, which indicates that the ore-bearing porphyry in the Naruo deposit area was formed in the Early Cretaceous and further implies that the Neo-tethys Ocean had not been closed before 124 Ma under a typical island-arc subduction environment. The εGr（t） of zircons from the granodiorite porphyry varies from 2.14 to 9.07, with an average of 5.18, and all zircons have εRf（t） values greater than 0; 176Hf/177Hf ratio is relatively high （0.282725-0.282986）. Combined with the zircon age--Hf isotope correlation diagram, the aforementioned data indicate that the source reservoir might be a region that is mixed with depleted mantle and ancient crust, which possibly contains more materials sourced from depleted mantle. Rock-forming ages and ore-forming ages of the Duolong ore concentrate area are 120-124 Ma and 118-119 Ma, respectively, which indicate 124-118 Ma represents the main rockforming and ore-forming stage within the area. The Naruo deposit is located in the north of the Bangongco-Nujiang suture, and it yielded a zircon LA-ICPMS age of 124.03 Ma. This indicates the Bangongco-Nujiang oceanic basin subducted towards the north at about 124 Ma, and the Neo-tethys Ocean had not been closed before the middle Early Cretaceous. It is possible that the crust-mantle mixing formed the series of large and giant porphyry copper-gold deposits in the Bangongco.

Experimental Study on Gold Dissolution from Hosting Minerals of the Hadamengou Gold Deposit and the Implications

The Hadamengou gold deposit is located in western part of the northern margin of the North China craton. It is a hydrothermal deposit related to alkaline magmatism. Dissolution of Au, Fe from pyrite and iron oxide （including magnetite and hematite） individual minerals in the three main types of ore shows： in iron oxides （magnetite and hematite）, Au and Fe were dissolved simultaneously and their solubilities are positively correlated, which means Au is mainly chemical-bonded （lattice gold） and/or colloidal-adsorbed in iron oxides; while in pyrite, on the contrary, Au dissolution obviously lags behind Fe and the solubility of Au shows negative relationship with that of Fe, which indicates Au is mainly hosted as grains of elemental gold （or native gold） within pyrite. Previous studies revealed that the Hadamengou gold deposit is characterized by intensive K-feldspathization and holds high content of iron oxides occasionally replaced by sulfides, which was caused by oxidizing K-enriched alkaline fluids under a stretching geodynamic setting. These geological features, together with the high Au-content in iron oxides, comparable with that of the Olympic Dam deposit in South Australia, suggest that this deposit is the first example of iron oxide-type gold deposits in China.

Mode of Occurrence of Gold in Micro-Disseminated Strata-Bound Sb-Au Deposits, Qinling Region, China

Optical studies, backscattered electron images, secondary ion spectrometry and highprecision transmission electron imaging demonstrate that gold is strongly correlated with arsenic on a microscopic scale in the sediment-hosted micro-disseminated gold deposits. The positive correlation between Au and As, despite varying Au/As ratio, is persistent in arsenian pyrite overgrowths and arsenopyrite. It is found that gold occurs in native state as submicro beads in association with arsenic-bearing sulfides. The extremely small grain size of gold may indicate a very rapid process of deposition.

Metallogenic Age and Genesis of Jinshan Gold Deposit, Jiangxi Province, China

The Jinshan gold deposit consists of gold\|bearing ultramylonite and gold\|bearing quartz vein ores. The Rb\|Sr isochron age of fluid inclusions in quartz from quartz veins is the same as that of the gold\|bearing ultramylonite, suggesting that both the types of orebodies were formed simultaneously in the Caledonian period, in the range 406-409 Ma. REE patterns and sulfur, lead, carbon, hydrogen and oxygen isotope data, as well as the composition of fluid inclusions, have shown that the ore\|forming fluids were derived from formation water, and the ore\|forming materials came from the gold\|hosted rocks. The Jinshan gold deposit occurring in a Caledonian brittle\|ductile zone in metamorphosed microclastic rocks owes its origin to Caledonian reworking processes.

还原性矽卡岩型金矿床基本特征、研究现状及在中国前景

还原性矽卡岩型金矿以独立金矿形式赋存于钙质沉积岩中,以金品位高(5~15 g/t)著称。目前,该类型金矿的总体研究程度较低,在成矿背景、还原性岩浆源区及成因、金高效富集机制等方面仍缺乏理解。笔者对该类型金矿的地质特征、时空分布规律、成矿机理、找矿标识等方面进行了系统梳理,探讨了该类金矿的研究难点及其在中国的成矿潜力和找矿前景。还原性矽卡岩型金矿具有以下特征:(1)独特的Au-Bi-Te-As±Co元素组合,缺乏Cu等贱金属;(2)矽卡岩以钙铁辉石为主,其次为石榴子石;(3)成矿岩体属于还原性钛铁矿系列,包括辉长闪长岩、闪长岩和花岗闪长岩等;(4)代表性低硫逸度的金属矿物,包括斜方砷铁矿、黑铋金矿、贫S的Te-Bi矿物。关键问题或薄弱环节主要有:(1)还原性岩浆存在温度、盐度、氧逸度、硫逸度、含水量、还原性组分类型及含量等多种属性,这些属性对还原性矽卡岩型金矿的形成有哪些影响?(2) Au可能以氯络合物、硫络合物、Bi-Te熔体、纳米絮状物等多种方式运移,还原性岩浆流体中Au的高效迁移及富集方式有哪些?(3)还原性成矿岩浆的氧化-还原性质有争议,部分学者认为岩浆始终为还原性,另一些学者认为母岩浆为氧化性,后期混入还原性物质;(4)存在深部W-Mo矿化、浅部Au-Sb-Bi矿化的金属元素分带现象,这种分带规律受哪些因素控制?总之,还原性矽卡岩型金矿在中国有着良好的成矿潜力和找矿前景,其中中国东部W/Sn成矿区(带)和Au成矿区(带)的叠加区域、西部还原性岩体分布区是该类金矿的有利勘探区。

Discovery of Cu-Ni-Zn-Sn-Fe intermetallic compounds and S-bearing alloys in the Zhaishang gold deposit, southern Gansu Province and its geological significance

Examination of ores by optical microscope and EPMA from the Zhaishang gold deposit, southern Gansu Province, has revealed an abundance of rare minerals. These include native metals, Cu-Ni-Zn-Sn-Fe polymetallic compounds and S-bearing alloys of Ni, Fe, Zn, Cu and Sn, occurring as native nickel, Zn-Cu alloy, Ni-Zn-Cu alloy, Sn-Zn-Ni-Cu alloy, Zn-Cu-Ni alloy, Zn-Fe-Cu-Sn-Ni alloy, Fe-Ni-S alloy, Sn-Fe-Ni-S alloy, Fe-Zn-Cu-Ni-S alloy, Zn-Ni-Cu-Fe-S alloy and others. Compared with the Zn-Cu alloy minerals discovered previously, these Zn-Cu minerals fall in the α or α+β portion in Zn-Cu alloy phase diagram, and the α portion has higher Cu content. Cu-Ni-Zn-Sn-Fe intermetallic compounds and S-bearing alloy minerals have not been previously reported in the literature. These rare alloys formed in a strongly reducing environment with absent oxygen and low sulfur activities.

Study on the carbonate ocelli-bearing lamprophyre dykes in the Ailaoshan gold deposit zone,Yunnan Province

Three carbonate ocelli-bearing lamprophyre dykes have been found in the Laowangzhai and Beiya gold orefields in the northern sector of the Ailaoshan gold deposit zone, Yunnan Province. Ocelli in the lamprophyre dykes are carbonates composed mainly of dolomite and calcite. Their trace elements, REE and C isotopic compositions are characteristic of carbonatite and the main mineral assemblages, major elements, trace elements and REE in the matrix are similar to those in the carbonate ocelli-barren lamprophyre dykes in the orefields, which are calc-alkaline lamprophyres that derived from the fertile mantle. The results indicate that the carbonate ocelli-bearing lamprophyre dykes in this area were produced at the time when the Himalayan lamprophyre magma evolved to a relatively late stage of silicate-carbonate liquid immiscibility. In the process of magmatic evolution there took place magmatic degassing with CO2 and H2O as the dominant released gases.

新疆哈密天宇北金钨矿地质特征及找矿预测

新疆天宇北金钨矿地处沙泉子断裂以南的中天山地块,为近年新发现的钨矿点,产于新太古界-古元古界天湖岩群碳酸盐岩与晚元古代斜长片麻状花岗岩、晚石炭世-早二叠世二长花岗岩接触带,且与以钨为主的1∶5万岩屑测量综合异常对应,与北山地区钨钼矿为同一成矿带,金钨矿具有多期岩浆活动及成矿作用特点。该矿点矿床类型属矽卡岩型钨矿,矿化以白钨矿化为主,伴生金,含矿二长花岗岩成矿时代为华力西期。槽探工程控制矿体长大于220 m,平均厚2.70 m,WO_(3)平均品位0.46%。钻探工程和物探异常激电测深双验证表明:钨矿化带在深部有一定的延伸。在该区及外围,围绕前寒武纪碳酸盐岩地层与中酸性岩浆岩的接触带,开展钨多金属地质找矿工作,找矿潜力大。

甘南阳山金矿床控矿构造的思考

阳山金矿床位于甘肃省陇南市文县境内,其大地构造位置处于西秦岭构造带的玛曲-略阳深大断裂南侧,是西秦岭地区为数有限的大型金矿床之一。该区控矿构造复杂,经过20多年的研究仍然存在很大争议。本文通过对矿区含矿构造的调查结合区域构造环境,重新厘定了含矿构造的特征,并对该矿床控矿构造的相关问题进行了讨论。研究结果显示,阳山金矿床控矿构造是以走向NEE,倾向NNW为主的偏脆性逆冲推覆构造系统,形成于俯冲-碰撞早期的韧性变形之后。含矿构造与千枚岩的千枚理没有直接的关系,可以与千枚理近于平行,或小角度斜交,或大角度斜交,主要以倾向北的断裂为主,少量为主逆冲断层上盘的倾向南的次级反向逆冲断裂,局部为顺千枚理的层间破裂。含矿构造对岩性没有选择性,但是不同岩性岩石的不同力学性质影响了含矿构造的发育与否和发育程度。阳山金矿区进一步工作中值得思考和关注的问题:(1)矿区构造格架上葛条湾-草坪梁复背斜可能不存在,也未起控矿作用;(2)成矿后断裂对矿体空间展布的影响;(3)在勘查编录中对各种构造破碎带需要详细的描述,以明确区分含矿构造与成矿后构造,为构建控矿构造体系准备素材,为进一步找矿预测和勘查工程部署提供技术支撑。

东昆仑东段中-晚三叠世区域岩浆-热液成矿系统

东昆仑成矿带在早中生代发生了大规模的成矿作用,形成了一系列脉状金矿床、脉状银铅锌矿床、斑岩型铜钼矿床和矽卡岩型铁多金属矿床,但这些矿床之间的成因联系尚不清楚。东昆仑东段以其多样的矿床类型为这一科学问题的研究提供了理想场所。在总结归纳东昆仑东段主要类型矿床时空分布和地质特征的基础上,通过系统分析各类矿床的成矿时代、成矿构造背景及成矿流体与物质来源,探讨它们之间的成因联系。研究结果显示,东昆仑东段各类矿床主要形成于中-晚三叠世(240~220 Ma),均是东昆仑古特提斯陆陆碰撞及后碰撞伸展作用的产物。此外,区内及外围东昆北地体中的各类矿床均具有相似的成矿流体与成矿物质来源,且与该时期广泛发育的深部岩浆作用密切相关,共同组成了一个巨型的岩浆-热液成矿系统,不同类型的矿化可能是该岩浆-热液系统不同演化阶段的产物。巴颜喀拉板块深俯冲及板块断离诱发软流圈地幔的上涌及随后的大规模岩浆-流体活动,富含金属挥发分的岩浆热液与上地壳的岩石和流体发生交代和流体混合,最终形成区内巨型的岩浆-热液成矿系统。基于该成矿系统,东昆仑东段具有寻找多类型共生矿床的潜力。

内蒙古北山老硐沟金矿石榴子石地球化学特征

老硐沟金矿是北山成矿带东段发现的中型金矿床,是多期次多阶段成矿作用叠加的产物,矿床成因类型复杂。矿床共分为5个矿段,其中Ⅲ矿段以矽卡岩矿体为主。矽卡岩矿物以石榴子石为主,可分为早、晚两期,早期石榴子石更具震荡环带。通过详细的镜下观察和电子探针对两期石榴子石进行了系统研究,早期石榴子石核部以钙铝榴石组分为主,向边部为钙铁-钙铝过渡组分;晚期石榴子石以钙铁榴石为主。石榴子石化学成分特征表明,早期矽卡岩化阶段,热液环境为中酸性、弱氧化—弱还原环境;后期铁质含量增多,氧逸度增加,热液环境碱性、氧化性增强。老硐沟金矿Ⅲ矿段石榴子石为钙铁-钙铝榴石系列,属热液交代成因,早期多形成钙铝-钙铁榴石,伴随铜矿化,晚期热液环境变化,钙铁榴石增多,黄铁矿化、毒砂矿化增多,造成金富集成矿。

铜陵天马山硫金矿床矽卡岩矿物学特征及矿石硫同位素地球化学研究

天马山硫金矿是铜陵矿集区典型的层控热液叠加改造型矿床,层状矿体中发育大量的矽卡岩矿物。为查明该矿床中矽卡岩矿物的类型及形成环境,探讨矽卡岩与硫、金成矿之间的关系,对主要的矽卡岩矿物开展了矿物学及矿物化学研究,并对矿石进行了硫同位素地球化学研究。研究表明:矿区内的矽卡岩矿物以石榴子石和辉石为主,其中石榴子石以钙铁榴石为主,属于钙铁榴石-钙铝榴石固熔体系列(Gro 0~18.73 And 80.54~99.00 Spe+Pyr+Alm 0.54~1.47);辉石以透辉石为主,其次为钙铁辉石,属于透辉石-钙铁辉石系列(Di 62.35~97.65 Hd 1.89~36.27 Jo 0.31~1.55)。天马山硫金矿的矿物组合(钙铁辉石+透辉石)属于氧化型矽卡岩,表明矽卡岩形成于相对高温和高氧逸度的条件。石榴子石和辉石端元组分特征及辉石Mn/Fe值(0.02~0.07)具有典型的矽卡岩型铜、金矿床特征。矿石硫同位素具有岩浆源的特征,与区内燕山期岩浆-成矿作用形成的矿石一致,而明显区别于喷流-沉积作用形成的矿石,显示成矿作用与燕山期岩浆活动具有密切的成因联系。燕山期中酸性岩浆交代碳酸盐岩围岩形成大量矽卡岩,矽卡岩矿物的形成增加了岩石的孔隙度和渗透率,为晚期硫、金矿床的形成提供了有利条件。

夹皮沟成矿带三道岔金矿区深部找矿发现及认识

三道岔金矿床是夹皮沟成矿带内的典型金矿床。针对以往提交的浅部资源开采殆尽,矿山面临资源危机的现状,亟须开展深部找矿工作,并取得实质性的找矿突破。通过梳理地质资料和科研成果,总结矿床地质特征和控矿规律,提出深部找矿新方向,通过工程验证,成功在3号含金断裂深部探获了矿体的第二富集段,总结找矿经验和认识,为同类矿床找矿提供借鉴。

甘肃花牛山金矿床成矿流体性质及矿床成因

花牛山金矿位于北山造山带南部,矿体产出于印支期钾长花岗岩脉与大理岩的接触部位,成矿期次可划分为早期矽卡岩期和晚期石英硫化物期(主成矿期)。主成矿期中石英和方解石的流体包裹体性质表明,Ⅰ、Ⅱ阶段成矿流体均具有中低温、中盐、中高密度以及含CO_(2)和CH_(4)的特征,属H2O-CO_(2)-NaCl体系;温度—盐度特征指示成矿流体主要为岩浆水和大气降水混合来源;方解石δ^(13)CV-PDB平均值为1.7‰,δ^(18)OV-PDB平均值为-22.5‰,δ^(18)OV-SMOW平均值为7.69‰,O同位素呈强烈分异特征,暗示着成矿流体为岩浆水和大气降水混合来源。矿石中黄铁矿S同位素δ^(34)S平均值为-9.73‰,其较大的负值或与围岩地层有关,指示该矿床硫源或为岩浆与地层的混合来源。成矿深度及压力特征表明花牛山金矿属于浅成型矿床。综合分析认为,花牛山金矿床为中低温热液交代型(矽卡岩型)金矿床,可能是晚三叠世时期花牛山地区多期次的后造山岩石圈伸展和幔源岩浆底侵作用导致来自深处的成矿流体沿着裂隙断裂向上移动,与围岩发生反应并与大气降水混合,随着压力降低,成矿物质沉淀富集,随之发生金成矿作用。

吉尔吉斯斯坦基奇桑德克金铜矿地质特征及找矿标志

基奇桑德克金铜矿为典型的矽卡岩型矿床,该区位于中天山多金属成矿带上,成矿条件优越。在总结以往地质成果的基础上,并结合新的勘查成果,对成矿条件进行了研究和分析,认为围岩地层与中酸性侵入岩体、构造、围岩蚀变是影响形矽卡岩型成金铜矿的主要因素;系统总结了矿床的找矿的标志,并对成矿有利部位进行了分析,为下一步勘查工作提供帮助。研究该区成矿地质条件及找矿标志,为寻找同类型金铜矿床提供了重要的借鉴意义。

Analyzing the Characteristics and Available Attributes of Skarn Gold Deposit Tailings

Skarn gold deposit tailings is a kind of tailings which is difficult to be utilized effectively. Taking a skarn gold deposit tailings from Hubei province, in China, as an example, the paper has tested and analyzed the tailings, and studied the characteristics and available attributes of the tailings, and provided scientific and efficient utilization approaches of tailings in the area of building materials further. The results showed that major mineral phases in the tailings is quartz, particle sizes of the tailings mainly exist in 10–100 μm, and the tailings has no pozzolanic activity. As a result, this kind of tailings can be used for building sand, and can be used as supplementary cementing material of concrete based on

中国含金夕卡岩矿床的分布和主要地质特征

夕卡岩金矿床主要分布于中国东部，特别是在长江中下游地区，并常和夕卡岩铜（铁或多金属）矿床共生。它们产生的有利构造环境为地台边缘的拗陷和褶皱带以及地台内部的深大断裂附近地区。主要控矿地层为石炭－二叠纪和三叠纪碳酸盐岩。有关侵入岩为钙－碱性闪长岩、石英闪长岩、石英二长闪长岩、花岗闪长岩、二长花岗岩及其浅成相，大多属燕山期。含金夕卡岩以钙夕卡岩为主，镁夕卡岩次之。在夕卡岩及其邻近的围岩中叠加有较强的退化热液蚀变，并常伴有Ｃｕ、Ａｕ、Ｆｅ、Ｍｏ、Ｐｂ、Ｚｎ、Ａｇ等矿化，显示明显的交代分带。总的矿化分带序列为：Ｆｅ（Ｃｕ）→Ｃｕ（Ｍｏ）→Ｃｕ、Ａｕ→Ａｕ→Ａｕ、Ｐｂ、Ｚｎ。在许多矿床中，发现有碲化物、铋化物和硒化物。因此，Ｃｕ、Ａｕ、Ｔｅ、Ａｓ、Ｂｉ、Ｐｂ、Ｚｎ、Ａｇ、Ｓｅ等元素在夕卡岩金矿床中相对富集。