Archean Mass-independent Fractionation of Sulfur Isotope:New Evidence of Bedded Sulfide Deposits in the Yanlingguan-Shihezhuang area of Xintai, Shandong Province

Multiple sulfur isotope ratios （^34S/^33S/^32S） of Archean bedded sulfides deposits were measured in the Yanlingguan Formation of the Taishan Group in Xintai, Shandong Province, East of China; 633S = -0.7%o to 3.8‰,δ^34S = 0.1‰-8.8‰, △^33S = -2.3‰ to -0.7‰. The sulfur isotope compositions show obvious mass-independent fractionation （MIF） signatures. The presence of MIF of sulfur isotope in Archean sulfides indicates that the sulfur was from products of photochemical reactions of volcanic SO2 induced by solar UV radiation, implying that the ozone shield was not formed in atmosphere at that time, and the oxygen level was less than 10-5 PAL （the present atmosphere level）. The sulfate produced by photolysis of SO2 with negative △^33S precipitated near the volcanic activity center; and the product of element S with positive △^33S precipitated far away from the volcanic activity center. The lower △^33S values of sulfide （-2.30‰ to --0.25‰） show that Shihezhuang was near the volcanic center, and sulfur was mostly from sulfate produced by photolysis. The higher △^33S values （-0.5‰ to -‰） indicate that Yanlingguan was far away from the volcanic center and that some of sulfur were from sulfate, another from element S produced by photolysis. The data points of sulfur isotope from Yanlingguan are in a line parallel to MFL （mass dependent fractionation line） on the plot of δ^34S--δ^33S, showing that the volcanic sulfur species went through the atmospheric cycle into the ocean, and then mass dependent fractionation occurred during deposition of sulfide. The data points of sulfur isotope from Shihezhuang represent a mix of different sulfur source.     

非质量硫同位素分馏效应研究进展

非质量硫同位素分馏效应是目前国际上最前沿的稳定同位素地球化学研究领域之一。在简要介绍非质量分馏理论的基础上,对近几年非质量硫同位素分馏效应的最新研究成果进行总结和分析。关于非质量硫同位素分馏的微观来源机制存在较多争议,有待于进一步探索;采用SF6为工作气体是现有硫同位素高精度测定的主要制样技术;非质量硫同位素分馏效应研究为火星大气演化及火星生命痕迹探询、古代大气氧化条件、地球早期硫循环、火山活动对气候的影响等重大地质科学问题的解释开辟了一条独特的新途径。最后对非质量硫同位素分馏领域研究趋势进行了探讨。     

相山西部牛头山铅锌矿化体成矿物质来源:原位硫同位素的制约

近年来,在相山铀矿田的西部牛头山地区深部发现了铅锌矿化体,其成因机制不明.为探讨牛头山铅锌矿化体物质来源,开展了硫化物原位硫同位素分析研究.根据硫化物矿物之间的充填和包裹关系判断,铅锌矿化体金属硫化物形成的先后顺序是:黄铁矿形成最早,方铅矿和闪锌矿次之,细脉状黄铜矿形成最晚.利用LA-MC-ICP-MS技术对矿化体中几种金属硫化物分别进行了系统的原位硫同位素分析.结果显示:黄铁矿、闪锌矿、方铅矿、细脉状黄铜矿的δ34S值介于-4.8‰~+5.4‰之间,各硫化物矿物之间硫同位素未达到完全平衡分馏,利用黄铁矿δ34S值得到的矿化流体δ34S_ΣS值（总硫同位素组成）近似为+3.7‰,与共生矿物对（闪锌矿-方铅矿）图解法得到的闪锌矿和方铅矿沉淀时矿化流体的δ34S_ΣS值（+3.2‰）相近,表明形成牛头山铅锌矿化体的矿化流体δ34S_ΣS值大约为+3.7‰,为岩浆硫.结合前人的岩浆岩年龄数据,我们判断该铅锌矿化体金属硫化物的硫可能主要来自次火山岩相花岗斑岩岩浆热液.同一薄片中闪锌矿δ34S值高于共生的方铅矿,表明两者硫同位素基本平衡,利用共生矿物对（闪锌矿-方铅矿）硫同位素温度计计算得出平衡温度为197~476℃,与前人通过脉石矿物流体包裹体得到的铅锌矿化流体温度基本一致.相山火山盆地与相邻的北武夷黄岗山、梨子坑等产铅锌矿的火山盆地具有相似的成矿条件及成矿物质来源,使相山火山盆地具有良好的铅锌多金属找矿前景.      

Sulfur isotope distribution in Late Silurian volcanic‐hosted massive sulfide deposits of the Hill End Trough,eastern Lachlan Fold Belt,New South Wales

Volcanic‐hosted massive sulfide (VHMS) deposits of the eastern Lachlan Fold Belt of New South Wales represent a VHMS district of major importance. Despite the metallogenic importance of this terrane, few data have been published for sulfur isotope distribution in the deposits, with the exception of previously published studies on Captains Flat and Woodlawn (Captains Flat‐Goulburn Trough) and Sunny Corner (Hill End Trough). Here is presented 105 new sulfur isotope analyses and collation of a further 92 analyses from unpublished sources on an additional 12 of the VHMS systems in the Hill End Trough. Measured δ³⁴S values range from ‐7.4% to 38.3%, mainly for massive and stockwork mineralisation. Sulfur isotope signatures for polymetallic sulfide mineralisation from the Lewis Ponds, Mt Bulga, Belara and Accost deposits (group 1) are all very similar and vary from ‐1.7% to 5.9%. Ore‐forming fluids for these deposits were likely to have been reducing, with sulfur derived largely from a magmatic source, either as a direct magmatic contribution accompanying felsic volcanism or indirectly through dissolution and recycling of rock sulfide in host volcanic sequences. Sulfur isotope signatures for sulfide mineralisation from the Calula, Commonwealth, Cordillera and Kempfield deposits, Peelwood mine and Sunny Corner (group 2) are similar and have average δ³⁴S values ranging from 5.4% to 8.1%. These deposits appear to have formed from ore fluids that were more oxidising than group 1 deposits, representing a mixed contribution of sulfur derived from partial reduction of seawater sulfate, in addition to sulfur from other sources. The δ³⁴S values for massive sulfides from the John Fardy deposit are the highest in the present study and have a range of 11.9–14.5%, suggesting a greater component of sulfur of seawater origin compared to other VHMS deposits in the Hill End Trough. For barite the sulfur isotope composition for samples from the Commonwealth, Stringers and Kempfield deposits ranges from 12.6% to 38.3%. More than 75% of barite samples have a sulfur isotope composition between 23.4 and 30.6%, close to the previously published estimates of the composition of seawater sulfate during Late Silurian to earliest Devonian times, providing supporting evidence that these deposits formed concurrently with the Late Silurian volcanic event. Sulfur isotope distribution appears to be independent of the host rock unit, although there appears to be a relation linking the sulfur isotope composition of different deposits to defined centres of felsic volcanism. The Mt Bulga, Lewis Ponds and Accost systems are close to coherent felsic volcanic rocks and/or intrusions and have sulfur isotope signatures with a stronger magmatic affinity than group 2 deposits. By contrast, group 2 deposits (including John Fardy) are characterised by ³⁴S‐enrichment and a lesser magmatic signature, are generally confined to clastic units and reworked volcanogenic sediments with lesser coherent volcanics in the local stratigraphy, and are interpreted to have formed distal from the magmatic source. An exception is the Belara deposit, which is hosted by reworked felsic volcanic rocks and has a more pronounced magmatic sulfur isotope signature.     

东天山康古尔金矿床成矿物源的同位素地球化学特征

康古尔金矿床属晚古生代火山岩区剪切带蚀变岩型金矿。同位素地球化学研究表明,矿石中铅为正常铅,热液系统硫同位素组成为陨石硫型,矿石中碳、钕同位素组成具深源特征,同时矿石与火山岩围岩中的Ｓｉ、Ｓｒ、Ｓ、Ｐｂ等同位素组成相近,说明成矿物质主要来自矿体围岩———火山岩,晚期有少量来自矿区附近的侵入岩。铅、锶同位素组成反映成矿过程中也有少量壳源物质的加入。     

Isotopes and Geochronology of the Meixian-type Pb-Zn-(Ag) Deposits, Central Fujian Rift, South China: Implications for Geological Events

Central Fujian Rift is another new and important volcanogenic massive sulfide Pb-Znpolymetallic metailogenetic belt. In order to find out the material genesis and mineralization period ofMeixian-type Pb-Zn-Ag deposits, S and Pb isotope analysis and isotope geochronology of ores and wallrocks for five major deposits are discussed. It is concluded that the composition of sulfur isotope fromsulfide ore vary slightly in different deposits and the mean value is close to zero with the δ34S rangingfrom -3.5‰ to 5.6‰ averaging at 2.0‰, which indicates that the sulfur might originate from magmaor possibly erupted directly from volcano or was leached from ore-hosted volcanic rock. The lead fromores in most deposits displays radioactive genesis character (206Pb/204Pb>18.140, 207Tb/204Pb>15.584,208Pb/204Pb>38.569) and lead isotope values of ores are higher than those of wall rocks, which indicatesthat the lead was likely leached from the ore-hosted volcanic rocks. Based on isotope data, twosignificant Pb-Zn metallogenesis are delineated, which are Mid- and Late-Proterozoic sedimentaryexhalative metallogenesis (The single zircon U-Pb, Sm-Nd isochronal and Ar-Ar dating ages of ore-hosted wall rocks are calculated to be among 933-1788 Ma.) and Yanshanian magmatic hydrothermalsuperimposed and alternated metallogenesis (intrusive SHRIMP zircon U-Pb and Rb-Sr isochronalages between 127-154 Ma).     

Hydrogen, Oxygen and Sulfur Isotope Studies of Seafloor Hydrothermal System at the Desmos Caldera, Manus Back-arc Basin, Papua New Guinea: An Analogue of Terrestrial Acid Hot Crater-lake

Abstract. The Onsen site is an active submarine hydrothermal system hosted by the Desmos caldera in the Eastern Manus Basin, Papua New Guinea. The hydrothermal fluid is very acidic (pH=1.5) and abundant native sulfur is deposited around the vent. The δ³⁴S values of native sulfur range from -6.5 to -9.3 %o. δ³⁴S values of H₂S and SO₄ in the hydrothermal fluid are -4.3 to -9.9 %o and +18.6 to +20.0 %o, respectively. These δ³⁴S values are significantly lower than those of the other hydrothermal systems so far reported. These low δ³⁴S values and the acidic nature of the vent fluids suggest that volcanic SO₂ gas plays an important role on the sulfur isotope systematic of the Onsen hydrothermal system. Relationship among the δ³⁴S values of S-bearing species can be successively explained by the model based on the disproportionation reaction starting from the volcanic SO₂ gas. The predicted δ³⁴S values of SO₂ agree with the measured whole rock δ³⁴S values. δD and δ¹⁸O values of clay minerals separated from the altered rock samples also suggest the contribution of the magmatic fluid to the hydrothermal system. Present stable isotopic study strongly suggests that the Onsen hydrothermal site in the Desmos caldera is a magmatic submarine hydrothermal system.     

西藏墨竹工卡县洞中拉铅锌矿床S、Pb同位素组成及成矿物质来源

为了探讨西藏墨竹工卡县洞中拉铅锌矿的成矿物质来源,研究矿床成矿机制,对该矿床的矿石样品进行了硫和铅同位素分析,并对其变化规律和成因意义进行讨论。研究结果表明,6件金属硫化物样品(闪锌矿、黄铜矿、方铅矿)的δ34S值变化于2.2‰～4.8‰之间,显示硫同位素组成比较稳定。根据共生硫化物对所确定的温度,该矿床属中低温热液矿床。6件金属硫化物样品206Pb/204Pb、207Pb/204Pb和208Pb/204Pb变化范围分别为18.628 0～18.629 6、15.698 0～15.699 9、39.077 5～39.082 4,平均值分别为18.628 70、15.699 02和39.079 37。硫和铅同位素研究结果表明,洞中拉铅锌矿床的硫主要来自沉积围岩,主要为无机还原成因,有少量硫来自本地区燕山晚期花岗岩;洞中拉铅锌矿床矿石铅主要来自上地壳物质。     

Origin of native sulfur ball from the Kueishantao hydrothermal field offshore northeast Taiwan: Evidence from trace and rare earth element composition

We first report the trace and rare earth element compositions of native sulfur ball with sulfur contents varying from 97.08 wt.% to 99.85 wt.% from the Kueishantao hydrothermal field, off NE Taiwan. We then discuss the sources of trace and rare earth elements incorporated into the native sulfur ball during formation. Comparison of our results with native sulfur from crater lakes and other volcanic areas shows the sulfur content of native sulfur ball from the Kueishantao hydrothermal field is very high, and that the rare earth element (REE) and trace element constituents of the native sulfur balls are very low (∑REE < 35 ppb). In the native sulfur ball, V, Cr, Co, Ni, Nb, Rb, Cs, Ba, Pb, Th, U, Al, Ti and REE are mostly derived from andesite; Mg, K and Mn are mostly derived from seawater; and Fe, Cu, Zn and Ni are partly derived from magma. Based on the sulfur contents, trace and rare earth element compositions, and local environment, we suggest that the growth of the native sulfur ball is significantly slower than that of native sulfur chimneys, which results in the relatively higher contents of trace and rare earth element contents in the native sulfur ball than in the native sulfur chimneys from the Kueishantao hydrothermal field. Finally, we suggest a “glue pudding” growth model for understanding the origin of the native sulfur ball in the Kueishantao hydrothermal field, whereby the native sulfur ball forms from a mixture of oxygenated seawater and acidic, low-temperature hydrothermal fluid with H₂S and SO₂ gases, and is subsequently shaped by tidal and/or bottom currents.     

红透山式块状硫化物铜锌矿床古火山环境及与成矿关系研究

“红透山式”块状硫化物铜锌矿床的成矿作用主要出现在三个较大的火山喷发-沉积旋迴中，双峰式火山岩构成了“红透山式”矿床的含矿岩系。呈透镜状、扁豆状的火山碎屑岩的发现为研究该类矿床提供了较为直观的地质依据。稀散元素和硫同位素特征亦表明该类矿床为古火山机构控制的海底火山喷发-沉积矿床。总结归纳了火山作用与成矿的关系。     

山东泰安朱家庄自然硫矿床地质概要

山东省泰安朱家庄自然硫矿床,赋存于鲁西断隆古近纪汶东陆相盆地。自然硫矿层在汶口组二段上亚段,泥质灰岩-含泥灰岩-含云灰岩-石膏岩韵律层中的白云岩-石膏岩层段发育。自然硫以胶态、晶态、土态3种形态产出,可划分为顺层型、准顺层型、斑杂型及不顺层型4大类10余种矿石类型。从矿区去膏化作用普遍、自然硫与石膏-硬石膏分别富集轻-重同位素的特征、油气显示明显及地下水主要径流方向自然硫矿化最强等各种证据,表明该矿属生物后生成因的矿床。     

A magmatic source of hydrothermal sulfur for the Prominent Hill deposit and associated prospects in the Olympic iron oxide copper-gold (IOCG) province of South Australia

The Prominent Hill deposit is a world-class iron oxide copper–gold (IOCG) deposit in South Australia, characterized by a high Cu/S ratio of the dominant Cu-(Fe) sulfides hosted by hematite breccias. It contains a total resource of 278 Mt of ore at 0.98% Cu and 0.75 g/t Au. Prominent Hill is one of several IOCG deposits and numerous prospects in the Olympic IOCG province that are temporally associated with the 1603–1575 Ma Gawler Range Volcanics, a large igneous province including co-magmatic granitoid intrusions of the Hiltaba Suite. Globally, IOCG deposits share many similar features in terms of their geological environment and mineral association. However, it is not yet clear whether sulfur and copper originate from the same source rocks and which hydrothermal redox processes created the characteristic iron oxide enrichment. Highly variable sulfur isotope compositions of sulfides and sulfates in IOCG deposits have previously been interpreted in terms of diverse sulfur sources that may include contributions from magmatic, sedimentary, seawater or evaporitic sulfur. In order to test these alternatives, we performed a detailed sulfur isotope study of Cu-(Fe) sulfides from Prominent Hill and IOCG prospects nearby. The Prominent Hill deposit shows a wide range in δ³⁴S_V-CDT between − 33.5‰ and 29.9‰ for Cu-(Fe) sulfides, and a narrower range of 4.3‰ to 15.8‰ for barite. Iron sulfides (pyrite, pyrrhotite) show a narrow range in sulfur isotope composition, whereas Cu-bearing sulfides show a much wider range, and more negative δ³⁴S_V-CDT values on average. We propose a two-stage sulfide mineralization model for the IOCG system in the Prominent Hill area, in which all hydrothermal sulfur is ultimately derived from a magmatic source that had a composition of 4.4 ± 2‰. The diversity in sulfur isotope composition can be produced by different fluid evolution pathways along reducing or oxidizing trajectories. A reduced sulfur evolution pathway is responsible for stage I mineralization, when intrusion-derived magmatic-hydrothermal fluids produced early pyrite and minor chalcopyrite at Prominent Hill, and iron ± copper sulfides in regional magnetite skarns and in some pervasively altered volcanic rocks of the Gawler Range Volcanics. Shallow-venting magmatic-hydrothermal fluids and subaerial volcanic gases that became completely oxidized by reaction with atmospheric oxygen produced sulfate and sulfuric acid with a sulfur isotope composition equal to their magmatic source. This highly oxidized ore fluid probably consisted dominantly of water from the hydrosphere, but contained magmatic solute components, notably sulfate, acidity and Cu. Sulfate reduction produced hydrothermal Cu sulfides with a wide range in sulfur isotope compositions from very negative to moderately positive values. Partial reaction of the Cu-rich stage II fluid with earlier stage I sulfides resulted in mixing of sulfur derived from sulfate reduction and from sulfides deposited during stage I. Modeling of the sulfur isotope fractionation processes in response to reducing and oxidizing pathways demonstrates that the entire spectrum of sulfur isotope data from stage I and stage II mineralization can be explained with a single, ultimately magmatic sulfur source. Such a magmatic sulfur source is also adequate to explain the complete spectrum of sulfur isotope data of other IOCG prospects and deposits in the Olympic province, including Olympic Dam. The results of our study challenge the conventional model that suggests the requirement of multiple and compositionally diverse sulfur sources in hematite-breccia hosted IOCG style mineralization.     

甘肃桦树沟（铁）铜矿床稀土元素及硫同位素地球化学意义

稀土元素和硫同位素地球化学研究表明．桦树沟（铁）铜矿床形成于近大陆边缘的海底裂谷环境，成矿物质主要来自元古代基性火山岩，硫主要来自海水，矿床的形成经历了水－岩作用、喷气沉积作用及后期变质改造作用等，为喷气沉积－变质改造型（铁）铜矿床。     

思茅盆地下白垩统蒸发岩硫同位素地球化学特征及其钾盐成矿意义

关于思茅盆地下白垩统勐野井组蒸发岩主要物源为海水的认识争议很少,但是关于其成矿时代和成矿模式的认识还有争议,关于陆源淡水对蒸发岩物质成分的影响还缺乏探讨。本文主要通过分析盆地内L2井27件蒸发岩样品的化学成分和硫同位素地球化学特征,结合邻区已发表的硫同位素数据,探讨了蒸发岩的物质来源、陆源淡水对蒸发岩物质成分的影响、成盐时代以及可能的钾盐成矿模式。结果表明:(1)思茅盆地蒸发岩受陆源淡水和火山热液补给,其中陆源淡水补给使蒸发岩硫同位素明显低于同一地质时期的其他海相样品;(2)海水可能自现今盆地北西方向补给,一级周期上海水补给存在两次,二级周期上海水补给至少存在七次;(3)物源海水的时代为中侏罗世,沉积析盐的时代为早白垩世晚期,可能的钾盐成矿模式为中侏罗世海水侧向迁移成矿。这些结果对解释思茅盆地及邻区海相蒸发岩异常低的硫同位素值、高硫同位素值与中侏罗世海水相当以及钾盐成矿缺失"碳酸盐岩相和硫酸盐岩相"有重要的意义。     

Isotopes and Geochronology of the Meixian-type Pb-Zn-(Ag)Deposits,Central Fujian Rift,South China:Implications for Geological Events

Central Fujian Rift is another new and important volcanogenic massive sulfide Pb-Zn polymetallic metallogenetic belt. In order to find out the material genesis and mineralization period of Meixian-type Pb-Zn-Ag deposits, S and Pb isotope analysis and isotope geochronology of ores and wall rocks for five major deposits are discussed. It is concluded that the composition of sulfur isotope from sulfide ore vary slightly in different deposits and the mean value is close to zero with the 834S ranging from -3.5‰ to ＋5.6‰ averaging at ＋2.0‰, which indicates that the sulfur might originate from magma or possibly erupted directly from volcano or was leached from ore-hosted volcanic rock. The lead from ores in most deposits displays radioactive genesis character （206pb/204pb〉18.140, 207Pb/204pb〉15.584, 208pb/204pb〉38.569） and lead isotope values of ores are higher than those of wall rocks, which indicates that the lead was likely leached from the ore-hosted volcanic rocks. Based on isotope data, two significant Pb-Zn metallogenesis are delineated, which are Mid- and Late-Proterozoic sedimentary exhalative metailogenesis （The single zircon U-Pb, Sm-Nd isochronal and Ar-Ar dating ages of ore- hosted wall rocks are calculated to be among 933-1788 Ma.） and Yanshanian magmatic hydrothermal superimposed and alternated metallogenesis （intrusive SHRIMP zircon U-Pb and Rb-Sr isochronal ages between 127-154 Ma）.     

Origin of Salts and Brine Evolution of Bolivian and Chilean Salars

Central Andes in Bolivia and northern Chile contain numerous internal drainage basins occupied by saline lakes and salt crusts (salars). Salts in inflow waters stem from two origins: alteration of volcanic rocks, which produces dilute waters, and brine recycling, which leads to brackish waters. Chilean alteration waters are three times more concentrated in average than Bolivian waters, which is related to a higher sulfur content in Chilean volcanoes. Brackish inflows stem from brines which leak out from present salars and mix with dilute groundwater. Most of the incoming salts are recycled salts. The cycling process is likely to have begun when ancient salars were buried by volcanic eruptions. Three major brine groups are found in Andean salars: alkaline, sulfate-rich, and calcium-rich brines. Evaporation modeling of inflows shows good agreement between predicted and observed brines in Chile. Alkaline salars are completely lacking in Chile, which is accounted for by higher sulfate and lower alkalinity of inflow waters, in turn related to the suspected higher sulfur content in Chilean volcanic rocks. Six Bolivian salars are alkaline, a lower number than that predicted by evaporative modeling. Deposition on the drainage basin of eolian sulfur eroded from native deposits shifts the initial alkaline evolution to sulfate brines. The occurrence of calcium-rich brines in Andean salars is not compatible with volcanic drainage basins, which can only produce alkaline or sulfate-rich weathering waters. The discrepancy is likely due to recycled calcic brines from ancient salars in sedimentary basins, now buried below volcanic formations. Calcic salars are not in equilibrium with their volcanic environment and may slowly change with time to sulfate-rich salars.     

滇中播卡铜矿床硫、铅同位素组成及其地质意义

滇中播卡铜矿床是著名“东川式”铜矿床的典型代表,但对其成矿物质来源和矿床成因认识存在争议。对矿区典型铜矿发育的金属硫化物进行硫和铅同位素组成分析,探讨其成矿物质来源。硫同位素测试结果表明,人占石铜矿金属硫化物的δ³⁴S值为1.6‰~10.7‰,指示硫以岩浆(火山喷发)作用为主要来源,并受到沉积作用影响。铅同位素测试结果则表明人占石铜矿、天生塘铜矿、竹箐凹子铜矿和白石岩铜矿中的铅主要来源于壳幔混合物质。综合前人研究和本次硫、铅同位素分析结果,认为播卡铜矿床成矿物质主要来自地幔,且受到地壳物质的混染。     

四川拉拉铜矿床成因研究

四川拉拉铜矿产于古元古宇河口群落凼组 ,成矿围岩为一套细碧角斑质火山岩及以硅质岩、条带状钠长岩和萤石化黑云母岩为主的喷气岩 ,矿体呈似层状、透镜状。矿石呈条带状、浸染状 ,部分呈角砾状 .。矿石矿物呈他形粒状以填隙方式产出 ,并见交代溶蚀结构和黄铁矿的胶状结构。矿石矿物主要为黄铜矿、黄铁矿及少量斑铜矿、辉钼矿。黄铁矿的常量元素、Co/Ni、S/Se均显示火山喷流 -沉积矿床的特征。铅同位素及硫同位素资料表明 ,铜铁等金属物质主要来源于围岩 ,而硫以深源为主 ,并有海水硫酸盐参与。矿床属火山喷流-沉积型硫化物矿床。     

Sulfur Isotope Variations of Metallic Ore Deposits in the Gyeongsang Basin,South Korea

Many metallic ore deposits of the Late Cretaceous to Early Tertiary periods are distributed in the Gyeongsang Basin. Previous and newly analyzed sulfur isotope data of 309 sulfide samples from 56 ore deposits were reviewed to discuss the genetic characteristics in relation to granitoid rocks. The metallogenic provinces of the Gyeongsang Basin are divided into the Au–Ag(–Cu–Pb–Zn) province in the western basin where the sedimentary rocks of the Shindong and Hayang groups are distributed, Pb–Zn(–Au–Ag–Cu), Cu–Pb–Zn(–Au–Ag), and Fe–W(–Mo) province in the central basin where the volcanic rocks of the Yucheon Group are dominant, and Cu(–Mo–W–Fe) province in the southeastern basin where both sedimentary rocks of the Hayang Group and Tertiary volcanic rocks are present. Average sulfur isotope compositions of the ore deposits show high tendencies ranging from 2.2 to 11.7‰ (average 5.4‰) in the Pb–Zn(–Au–Ag–Cu) province, ?0.7 to 11.5‰ (average 4.6‰) in the Cu–Pb–Zn(–Au–Ag) province, and 3.7 to 11.4‰ (average 7.5‰) in the Fe–W(–Mo) province in relation to magnetite‐series granitoids, whereas they are low in the Au–Ag(–Cu–Pb–Zn) province in relation to ilmenite‐series granitoids, ranging from ?2.9 to 5.7‰ (average 1.7‰). In the Cu(–Mo–W–Fe) province δ³⁴S values are intermediate ranging from 0.3 to 7.7‰ (average 3.6‰) and locally high δ³⁴S values are likely attributable to sulfur derived from the Tertiary volcanic rocks during hydrothermal alteration through faults commonly developed in this region. Magma originated by the partial melting of the ³⁴S‐enriched oceanic plate intruded into the volcanic rocks and formed magnetite‐series granitoids in the central basin, which contributed to high δ³⁴S values of the metallic deposits. Conversely, ilmenite‐series granitoids were formed by assimilation of sedimentary rocks rich in organic sulfur that influenced the low δ³⁴S values of the deposits in the western and southeastern provinces.