西秦岭金龙山卡林型金矿床地质-地球化学及矿床成因研究

金龙山金矿床位于南秦岭造山带的复理石褶冲带中,赋矿围岩为碎屑岩-碳酸盐建造,矿化明显受地层岩性与韧-脆性构造发育程度的控制。矿床稀土元素地球化学研究表明,地层岩石、矿石和热液矿物的轻重稀土分异程度和特征参数基本一致,表明成矿流体应主要来自于赋矿地层。铅同位素研究表明,地层岩石、矿石和热液矿物均具有较高的放射性成因的铅同位素组成,且均落入南秦岭造山带的泥盆系范围内,暗示铅也主要来自赋矿地层。对前人已有的碳-氧-硫-氢同位素组成和流体包裹体数据综合分析表明,碳和氧应主要来自海相碳酸盐的溶解作用,硫主要来自海相硫酸盐的热化学还原反应;从成矿早阶段到晚阶段,成矿流体的δ18O及δD值向大气降水线＂漂移＂,指示成矿流体以盆地建造水和变质水为主,在晚阶段有大气降水加入。金龙山金矿床与卡林型金矿床的矿床地质-地球化学特征相似,应属于卡林型金矿床,其形成于秦岭造山带陆内造山作用过程中,多层次陆壳叠置加厚的地球动力学背景,是陆内碰撞造山作用的产物。     

Ore Geology, Fluid Geochemistry and Genesis of the Shanggong Gold Deposit, Eastern Qinling Orogen, China

Abstract. The Shanggong Au deposit in the Xiong'er Terrane, East Qinling, has reserves of about 30 t Au, making it one of the largest orogenic‐type Au deposits hosted in volcanic rocks in China. The deposit is hosted in the andesitic assemblage of the Xiong'er Group of 1.85?1.4 Ga. Three stages of hydrothermal ore‐forming processes are recognized, Early (E), Middle (M) and Late (L), characterised by quartz‐pyrite, polymetallic sulfides and carbonate‐quartz, respectively. Homogenization temperatures of fluid inclusions are between 380‐320d?C for the E‐stage, 300‐220d?C for the M‐stage and 200‐120d?C for the L‐stage. The composition of fluid inclusions changed from CO₂‐rich in the E‐stage to CO₂‐poor L‐stage. The M‐stage fluid has the highest contents of cations and anions (e.g., SO₄^2‐, Cl¹, K+), the highest (K+Na)/(Mg+Ca) and lowest CO₂/H₂O ratios, which probably resulted from CO₂ phase separation. This, together with the alkaline and reducing conditions, as indicated by highest pH and lowest Eh values, is most conducive to the deposition of polymetallic sulfides and native elements such as Au, Ag and Te. H‐O isotope systematics indicate that ore fluids evolved from deep‐sourced through to shallow‐sourced, with the M‐stage being a mixing phase of these two fluid‐systems. Nineteen δ¹⁸O_W values, from 4.2 to 13.4 %o, averaging 8.1 %o, suggest that the E‐stage fluids derived from metamorphic devolatilization of sedimentary rocks at depth. Comparison of the H‐O 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 and metals for the Shanggong Au deposit. Instead, a source which meets the isotopic constraints, is a carbonaceous carbonate‐sandstone‐shale‐chert (CSC) sequence, which is present in the Guandaokou and Luanchuan Groups in the south of the Xiong'er Terrane. This conclusion is supported by thirteen high δ¹⁸O values of the Meso‐Neoproterozoic strata south of the Machaoying fault, and the high δ¹⁸O_W values calculated for their possibly metamorphic fluids. It can be also supported by previous observation that the Guandaokou and Luanchuan Groups were underthrust beneath the Xiong'er Terrane, during the Mesozoic collision between the Yangtze and Sinokorean continents. Available isotope ages, together with geological field data, constrain the timing of the Au metallogenesis between 250?110 Ma. This metallogenesis and associated granitic magmatism, can be related to the Yangtze‐Sinokorean continental collision that resulted in the formation of the Qinling Orogen. This collision event progressed from early compression (Triassic to Early Jurassic), through middle compression‐to‐extension transition (Late Jurassic to Early Cretaceous), to late extension (Cretaceous). These three stages in the evolution of the Qinling Orogen form the basis of an ore genesis model that combines collisional orogeny, metallogeny and fluid flow (CMF model). These three evolutionary stages correspond to the three‐stages of ore‐forming fluids of the Shanggong Au deposit. We conclude that the formation of the Shanggong Au deposit is a result of the Mesozoic northward intracontinental A‐type subduction along the Machaoying fault during Yangtze‐Sinokorean continental collision, which led to the metamorphic devolatilization of the CSC sequence, thereby providing both fluids and metals.     

Wall Rock Alteration Zoning Characteristics of the Shanggong Gold Deposit,Eastern Qinling Orogen, China

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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.     

Geochemistry of Pyrite from the Gangcha Gold Deposit, West Qinling Orogen, China: Implications for Ore Genesis

The Gangcha gold deposit was discovered in 2011 in the Xiahe-Hezuo region, West Qinling Orogen, China. Five types of pyrite have been identified in the ore according to the detailed mineral paragenetic studies. Geochemical data are presented for type I pyrite (py1) rim-core zonation and for the different types of pyrite based on in-situ laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and electron probe microanalysis (EPMA). The results show that pyrites are characterized with heterogeneous Au concentrations, which indicate that Au occurs mainly as micro- or nano-particle native inclusions. Time-resolved depth profiles demonstrate that As, Co and Ni occur as solid solutions in pyrite, whereas Cu, Pb, Zn and Ag occur mainly as inclusions. Trace element concentrations differ between rims and cores in py1, and the differences also exist within different pyrite types. These differences indicate complex chemical evolution of the ore-forming fluids, and the overall geology, geochronology, and stable isotope and pyrite data suggest that the ore-forming fluids were closely linked to magmatic activity during the Triassic Period in West Qinling orogenic belt.     

Characteristics of the Spotted Structure and Its Implication For Gold Mineralization in the Baguamiao Gold Deposit, Western Qinling, China

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A Magmatic Related Gold System in the Xiahe-Hezuo District,Western Qinling Orogen, China

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粤西黄泥坑金矿床地质特征及成因浅析

粤西一桂东毗邻区是重要的剪切带型金矿成矿带。广宁县黄泥坑金矿床是近年来新发现的产于寒武纪黑色浅变质岩系,且受构造与岩体双重控制的金矿床。该矿床的发现是广东省继河台金矿发现后的又一找矿突破。本文阐述了黄泥坑金矿床成矿地质背景、矿床地质特征,同时从宏观地质现象角度,对矿床成因进行了初步的分析,认为该矿床是受剪切作用控制的浅成中一低温热液矿床。     

西秦岭大店沟金矿成矿流体演化及矿床成因

大店沟金矿是西秦岭成矿带近年来新发现的中型金矿床,金矿体赋存在下古生界丹凤群木其滩组绢云绿泥石英片岩中,叠加在北东东向脆韧性剪切带中的脆性构造为成矿结构面。在总结控矿地质特征的基础上,通过开展系统的流体包裹体、稳定同位素地球化学研究及成矿流体演化、矿床成因探讨,认为成矿期共分半自形黄铁矿、它形粒状黄铁矿、石英多金属硫化物和碳酸盐-黄铁矿4个成矿阶段,其中它形黄铁矿阶段和石英多金属硫化物阶段为最主要成矿阶段。流体包裹体类型以水溶液包裹体、CO₂三相包裹体和纯CO₂包裹体为主,成矿温度集中在120~256 ℃之间,成矿流体盐度为4.03%~15.27%。H-O同位素研究显示成矿热液主要为变质水混合大气降水,S同位素组成特征表明成矿物质来自深源;流体不混溶和沸腾作用是金沉淀的主要机制,矿床成因类型为造山型金矿。通过成矿结构面舒缓波状特征规律总结,判断成矿流体沿成矿结构面自南西深部向北东浅部运移、沉淀,形成分段富集矿化。     

邛莫金矿床中块硫锑铜矿含硒性及其特征

硒的块硫锑铜矿产于西秦岭邛莫金矿床中,与其伴生的矿物有硒汞矿、硒铅矿、硒锑矿、斜方硒镍矿、硒铜镍矿、硒质辉锑矿、自然金以及石英、重晶石等。 含硒的块硫锑铜矿平均显微硬度VHN50=247.5kg/mm2,相当于摩氏硬度4.2。电子探 针分析结果(w,％)为：Sb 25.79,Cu 38.20,S 21.12,Se 1 2.76,Hg 0.0 0～1.49(平均0.58),Ag 0.00～0.33(平均0.09),As 0.00～2.01(平均0.76)。根据成分中S e/(S+Se)比值(原子比)＜0.2抑≥0.2,可将所测矿物划分为含硒质块硫锑铜矿与硒质块硫锑 铜矿。它们的化学分子式分别为: (Cu2.84Hg0.01)2.85(Sb1.00A s0.07)1.07(S3.54Se0.46) 4.00和(Cu3.05Hg0.03)3.08(Sb1.07As0.03) 1.10(S2.77Se1.23)4.00。代表性的反射率(％): (470nm) Rγ'=22.84～22.50, Rα'= 27.92～27.99; (550 nm) Rγ'= 22.63～22.76, Rα'=2 7. 79～28.11; (590nm) Rγ'=22.92～22.08, R α'=28.27～28. 72; (650nm) Rγ'=23.08～23.76, Rα'=28.79～29.13。     

南秦岭青山金矿床地质特征、控矿因素及其成因探讨

青山金矿床位于南秦岭镇安盆地。矿体呈脉状、囊状、透镜状、似层状等产出,主要赋存在上泥盆统九里坪组与下石炭统界河街组假整合面之上的界河街组的黑色碳质板岩和碳酸盐岩中。在燕山早中期的陆内造山过程中,该区区域构造继承了泥盆纪奠定的棋盘构造格局,控制了矿床的定位,而矿区棋盘构造控制了矿段的分布和矿体产出。矿石分为原生的含金黄铁矿-菱铁矿型及铁帽型。矿石中主要金属矿物为菱铁矿、黄铁矿、褐铁矿．成矿元素以Au—Ag—AS—Sb—Ba组合为特征,与区域低温矿床的元素组合相一致。矿床成矿温度介于160～220℃,成矿流体为重碳酸盐一氯化钠型地下热卤水。初步研究表明．该矿床是地热驱动热卤水循环萃取矿源层中的矿质而形成的热泉型金矿床。     

新疆红十井金矿床特征及成因

文章通过K_Ar同位素年龄 ,氢、氧、硫、铅等同位素测试和流体包裹研究 ,结合红十井金矿床的地质、矿区岩石化学、微量元素及稀土元素地球化学特征 ,探讨了红十井金矿床含金建造与金矿关系及矿床成因。研究表明红十井金矿床为晚古生代裂谷带火山岩区受韧性剪切带控制的中_低温热液矿床 ,矿体赋存于中石炭统玄武 (玢 )岩及凝灰质砂岩组成的含金建造内 ,成矿物质主要来源于含金建造 ,矿化以蚀变岩型和石英脉型为主。成矿年龄为2 0 9～ 2 6 7Ma。成矿流体为岩浆水、玄武 (玢 )岩和凝灰质砂岩的变质水、建造水和大气降水的混合溶液 ,δD为 - 114.6‰～ - 6 8.8‰ ,δ18OH2 O变化为 - 2 .47‰～ 5 .91‰。成矿温度为 115～ 381℃ ,成矿压力为 471.8× 10 5～ 6 75 .9× 10 5Pa ;流体盐度w(NaCleq)为 2 .18%～ 16 .77% ,平均 7.79% ,流体属中_低盐度、H2 O_CO2 体系。     

内蒙古长山壕金矿矿床地球化学特征与成因研究

长山壕金矿是近年来在内蒙古中部发现的一个大型浅变质碎屑岩型金矿,产于中—新元古代白云鄂博群比鲁特组碳质板岩和千枚岩中,矿体与围岩呈渐变关系。矿石呈硫化物细脉和石英硫化物细脉状,产于地层层理、节理和破碎带中,与地层同步褶皱变形。矿石的微量元素特征与围岩一致,矿石铅同位素为208Pb/204Pb为37.430 8～38.9792,207Pb/204Pb为15.452 2～15.674 1,206Pb/204Pb为17.109～18.921 7,与地层铅同位素接近。流体包裹体以液相包裹体为主,均一温度230～370℃,平均286.8℃;盐度w(NaCl)为6.01%～20.52%,平均10.84%;包裹体水的δD为-108‰～-112‰,δ18O为6.4‰～9.4‰。地质地球化学特征表明成矿物质来自地层,成矿热液主要来自地层水。研究认为长山壕金矿为沉积-变质型金矿,后期的岩浆活动对成矿作用影响较小。     

吉林延边五凤、五星山金矿床地球化学特征及其成因

五凤和五星山金矿为延边地区中生代火山岩金、铜成矿带中典型的金矿床.通过岩石化学、成矿元素、流体包裹体和同位素组成等方面的分析,提出五凤和五星山金矿床属于典型的冰长石-绢云母型浅成低温热液型金矿床,其形成是深部火山-热液流体系统与浅成大气流体的混合.成矿构造环境与陆内造山带后期垮塌机制有关,造山带的垮塌与古太平洋板块斜向俯冲导致的大型走滑剪切有密切的成因联系.     

Metallogeny,Minerogenic Series,and Gold Mineralization of the Qinling Orogen,China

The Qinling orogen extends 1650 km E-W and has a width of 95-255 km. It has a long evolutionary history of ～3.02 Ga and a mineralization history of approximately 2.5 Ga. There are more than 400 mineral deposits of Au, Ag, Pb, Zn, Sb, Hg, Mo, W, Fe, Ni, Mn, rare elements, REE, U, V, P, As, Ba, Sr, Ti, Al, pyrite, gypsum, trona, halite, glauberite, mirabilite, blue asbestos, fluorite, rock crystal, mica, vermiculite, graphite, kyanite, andalusite, talc, fireclay, and K-feldspar in the Qinling orogen and adjacent areas. The deposits were formed in six tectono-minerogenic cycles and have been grouped into 21 regional minerogenic series.

The metallogeny of the Qinling orogen is closely associated with the tectonic evolution of the orogen, and most of the ore deposits were formed in two important metallogenic periods: (1) Middle Proterozoic to Early Paleozoic, which was characterized by spreading and rifting-related minerogenetic processes; during this period, the minerogenic series are directly associated with basic-ultrabasic magmatism and marine volcanism resulting from spreading-rifting and deep faulting; (2) Mesozoic, when mineralization was controlled by intracontinental subduction and postorogenic relaxational taphrogenesis or extension; the minerogenetic series are associated with intermediate-acid magmatism and terrestrial volcanism.

Gold is one of the most important ore-forming commodities in the Qinling orogen. Over 80% of those gold deposits were formed in the Mesozoic and Cenozoic and are related genetically to magmatism, terrestrial volcanism, and alluvial sedimentation. Most gold deposits in the Qinling orogenic belt are of hydrothermal origin. The Dashui-type gold deposits may be a new category of high-sulfi-dation epithermal gold deposits hosted by carbonate rocks of the Upper Paleozoic and Triassic in the southwestern part of the Qinling orogen. Shuangwangtype gold deposits in the middle of the Qinling orogen are characterized by low-grade (but large in terms of tonnage) ores hosted by brecciated and banded albitites, which are thought to have been formed by Yanshanian (late Mesozoic) magmatic-hydrothermal fluids injected into the Devonian sedimentary rocks. Carlin-type, quartz vein-type, and placer-type deposits also are important in this continental orogenic belt and adjacent areas.     

西秦岭大桥金矿硅质岩硅氧同位素特征及成因探讨

西秦岭大桥金矿床位于岷县-宕昌和舟曲-成县大断裂之间,金矿体赋存于三叠系下部灰岩、泥质板岩岩性不整合界面处的硅质角砾岩中。硅质角砾岩呈似层状、板状和透镜状产出,倾向于断裂带分布两侧,矿石构造以角砾状、被膜状、皮壳状、细脉-网脉状、孔隙状构造为主。矿石矿物主要为黄铁矿、白铁矿、磁黄铁矿、毒砂、闪锌矿、方铅矿、黄铜矿,蚀变以硅化、绢云母、方解石为主,矿化元素组合为Au、Sb、Ag、As、Hg、W。利用氧同位素地质温度计估算的硅质岩形成温度为142~218℃,硅质岩δ30Si值为-0.7‰~0.4‰,δ18O为12.8‰~17.9‰,与热水-热泉华型金矿床地质特征及同位素特征一致。综合研究认为,大桥金矿硅质岩为热水-热泉形成,硅质角砾岩是在断裂带的周期性破裂-自封闭条件下,由流体超压引发的岩石破裂形成。     

天柱主山冲金矿地质特征及成因浅析

主山冲金矿民采历史悠久。本文在前人工作的基础上,主要结合地质现象,从地层、构造、石英脉地质特征、矿石组分、金的富集和产出特征、成矿温度、矿床成因等方面对该金矿的地质特征进行了较全面的探讨,为以后对该区金矿研究提供一定的参考。     

南秦岭柞水-山阳矿集区王家坪金矿床地质特征及矿床成因探讨

王家坪矿床位于南秦岭柞水-山阳矿集区东部,金矿体主要产于上泥盆统星红铺组沉积地层中;金属矿物以黄铁矿为主,与金成矿关系密切的矿物为黄铁矿和雌黄.笔者利用LA-ICPMS和LA-MC-ICPMS对成矿期不同阶段硫化物进行微量元素及硫同位素研究,结果表明,该矿床成矿中阶段黄铁矿Co/Ni值为0.003～1.1,均小于1,暗...     

金厂沟梁金矿床地质特征及成因

详细叙述了金厂沟梁金矿围岩和岩浆岩的含金性、构造控矿条件、围岩蚀变与矿化的关系、矿石类型和结构构造。指出该矿为岩浆热液型金矿。     

Geological Characteristics and Genesis of Xiayingfang Gold Deposit in Pingquan,Hebei Province, China

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