Isotopic Geochronology of the Late Paleozoic Kanggur Gold Deposit of East Tianshan Mountains, Xinjiang, NW China

Abstract: The Kanggur gold deposit lies in East Tianshan mountains, eastern section of Central Asia orogenic belt. The gold mineralization occurs on the northern margin of the Aqishan‐Yamansu Paleozoic island arc in the Tarim Plate. It was hosted mainly in Middle‐Lower Carboniferous calc‐alkaline volcanic rocks, and controlled by the distributions of syn‐tectonic intrusions and ductile shear zones. In order to determine ore‐forming age of the Kanggur deposit, samples were collected from ores, wall rocks, altered rocks and intrusions. The dating methods include Rb‐Sr isochron and Sm‐Nd isochron, and secondly ⁴⁰Ar/³⁹Ar age spectrum, U‐Pb and Pb‐Pb methods. Based on the mineral assemblage and crosscutting relationship of ore veins, five mineralization stages are identified. This result is confirmed by isotope geochronologic data. The first stage featuring formation of pyrite‐bearing phyllic rock, is mineralogically represented by pyrite, sericite and quartz with poor native gold. The Rb‐Sr isochron age of this stage is 2905 Ma. The second stage represents the main ore‐forming stage and is characterized by native gold–quartz–pyrite–magnetite–chlorite assemblage. Magnetite and pyrite of this stage are dated by Sm‐Nd isochron at 290.47.2 Ma and fluid inclusion in quartz is dated by Rb‐Sr isochron at 282.35 Ma. The third mineralization stage features native gold–quartz–pyrite vein. In the fourth stage, Au‐bearing polymetallic sulfide‐quartz veins formed. Fluid inclusions in quartz are dated by Rb‐Sr isochron method at 25821 Ma. The fifth stage is composed of sulfide‐free quartz–carbonate veins with Rb‐Sr age of 2547 Ma. The first and second stages are related to ductile‐brittle deformation of shear zones, and are named dynamo‐metamorphic hydrothermal period. The third to fifth stages related to intrusive processes of tonalite and brittle fracturing of the shear zones, are called magmato‐hydrothermal mineralization period. The Rb‐Sr isochron age of 2905 Ma of the altered andesite in the Kanggur mine area may reflect timing of regional ductile shear zone. The Rb‐Sr isochron age of 28216 Ma of the quartz‐syenite porphyry and the zircon U‐Pb age of 2757 Ma of tonalite in the north of Kanggur gold mine area are consistent with the age of gold mineralization (290‐254 Ma). This correspondence indicates that the tonalite and subvolcanic rocks may have been related to gold mineralization. The Rb–Sr, Sm‐Nd and U‐Pb ages and regional geology support the hypothesis that the Kanggur gold deposit was formed during collisional orogenesis process in Late Variscan.     

西南天山萨瓦亚尔顿金(锑)矿床成矿时代与赋矿地层时代

通过对萨瓦亚尔顿金（锑）矿床矿石中共生石英的流体包裹体作Rb-Sr等时线年龄（231±10Ma） 的研究,表明成矿时代为印支期,与南天山造山带陆内造山晚阶段一致。由于矿区主体赋矿地层的（2）（3） 岩性段中无化石,故采集其中的一组无矿石英脉作包裹体Rb-Sr等时线年龄（389±42Ma） ,推测赋矿地层年龄上限为志留 泥盆纪。根据近年来在赋矿岩系的（1）（1） 段所发现的动物化石年代依据,指出含矿浊积岩系东部和西部二个岩性段即（1） 和（4）段为石炭系。     

Early Paleozoic Magmatism and Gold Mineralization in the Northern Aitun, NW China

Abstract This paper discusses the relationships between granitic magmatism and gold mineralization and the exhumation history of the Dapinggou gold deposit in northern Altun, NW China based on the geochronological data, including zircon U‐Pb ages, Rb‐Sr isochron age and ⁴⁰Ar‐³⁹Ar dating and MDD modeling data. The main granitic magmatism age in this area is attained from the ID TIMS U‐Pb geochronology of zircons from the Kuoshibulak granite, the biggest granite in the northern Altun area, which gives a concordant age of 443±5 Ma in the Late Ordovician. Zircon ID TIMS U‐Pb geochronology of the West Dapinggou biotite granite west of the Dapinggou gold deposit gives concordant ages around 485±10 Ma, representing the early stage of Ordovician magmatism. The Rb‐Sr isochron age (487±21 Ma) of 6 quartz inclusion samples from quartz veins in this gold deposit is very close to that of the West Dapinggou granite. MDD modeling of step heating ⁴⁰Ar‐³⁹Ar data of K‐feldspar from the same West Dapinggou biotite granite gives a rapid cooling history from 300°C to 150°C during 200–185 Ma. According to the age data and the geological setting of this area, we conclude that the Dapinggou gold deposit was formed at the early stage of the Early Paleozoic granitic magmatism in northern Altun, and exhumed in the Early Jurassic due to the normal faulting of the Lapeiquan detachment. The Early Paleozoic magmatism may provide heat source and produce geological fluids, which are very important for gold mineralization. Exhumation in the Mesozoic caused the uplift of the deposit towards the ground surface.     

胶西北东季金矿床钾长石和石英的Ar-Ar年龄及其意义

东季金矿床位于焦家_新城金矿带中 ,其围岩蚀变以钾长石化为特征。作者采用Ar_Ar同位素定年方法对东季金矿床矿脉中的石英及其两侧的蚀变钾长石进行了测试 ,获得钾长石Ar_Ar坪年龄为 (116 .0 7± 0 .30 )Ma ,等时线年龄为 (116 .34± 0 .81)Ma ,石英脉中石英Ar_Ar坪年龄为 (115 .2 2± 0 .2 0 )Ma ,等时线年龄为(114.44± 0 .16 )Ma。这些年龄基本上代表了焦家断裂成矿带的成矿时限。     

Geochronology and fluid source constraints of the Songligou gold‐telluride deposit,western Henan Province,China: Analysis of genetic implications

The Songligou gold‐telluride deposit, located in Songxian County, western Henan Province, China, is one of many gold‐telluride deposits in the Xiaoqinling‐Xiong'ershan district. Gold orebodies occur within the Taihua Supergroup and are controlled by the WNW F101 Fault, and the fault was cut across by a granite porphyry dike. Common minerals in gold orebodies include quartz, chlorite, epidote, K‐feldspar, calcite, fluorite, sericite, phlogopite, bastnasite, pyrite, galena, chalcopyrite, sphalerite, tellurides, gold, bismuthinite, magnetite, and hematite, and pyrite is the dominant sulfide. Four mineralization stages are recognized, including pyrite‐quartz stage (I), quartz‐pyrite stage (II), gold‐telluride stage (III), and quartz‐calcite stage (IV). This work reports the Rb–Sr age of gold‐telluride‐bearing pyrite and zircon U–Pb age of granite porphyry, as well as S isotope data of pyrite and galena. The pyrite Rb–Sr isochron age is 126.6 ± 2.3 Ma (MSWD = 1.8), and the average zircon U–Pb age of granite porphyry is 166.8 ± 4.1 Ma (MSWD = 4.9). (⁸⁷Sr/⁸⁶Sr) _i values of pyrite and δ³⁴S values of sulfides vary from 0.7104 to 0.7105 and ?11.84 to 0.28‰, respectively. The obtained Rb–Sr isochron age represents the ore formation age of the Songligou gold‐telluride deposit, which is much younger than the zircon U–Pb age of the granite porphyry. Strontium and S isotopes, together with the presence of bastnaesite, suggest that the ore‐forming fluid was derived from felsic magmas with input of a mantle component and subsequently interacted with the Taihua Supergroup. Tellurium was derived from metasomatized mantle and was related to the subduction of the Shangdan oceanic crust and Izanagi plate beneath the North China Craton (NCC). This deposit is a part of the Early Cretaceous large‐scale gold mineralization in east NCC and formed in an extensional tectonic setting.     

Sr Isotope Constraints on the Age and Source of Ore—Forming Materials of Gold Deposits,Southwestern Hunan

We have measured Rb and Sr concentrations in fluid inclusions of quartz in gold deposits, southwestern Hunan. The Rb-Sr isochron ages of 435±9Ma and 412±33Ma are respectively determined, revealing that gold mineralization in this area took place in the Caledonian period rather than in the Wuling-Xuefeng period as traditionally considered. Sr isotope geochemistry of the hydrothermal fluid indicates that the ore-forming materials are of crust origin, derived largely from the ore-hosting strata rather than from the basic dikes.     

Metallogenetic Mechanism and Timing of Late Superimposing Fluid Mineralization in the Dongguashan Diplogenetic Stratified Copper Deposit,Anhui Province

1 Introduction The region of the middle-lower reach of the Yangtze River is an important mineralized belt of Fe, Cu, Au, S and other elements, with a series of sedimentary-hydrothermal diplogenetic mineral deposits (Xu and Zhu, 1978; Liu et al., 1984; Gu and Xu, 1986; Gu et al., 1993, 2000; Zhai et al., 1992). Some geologists thought that the Carboniferous massive sulfide exhalative sediment was the basis of the late diplogenetic mineralization (Gu and Xu, 1986; Gu et al., 1993, 2000); o…     

东天山东戈壁钼矿床辉钼矿Re-Os年龄及印支期成矿事件

东戈壁超大型钼矿床位于新疆境内的东天山觉罗塔格成矿带.8件辉钼矿样品Re-Os同位素年龄介于228.7±2.7Ma ～ 241.7±0.9Ma,等时线年龄为231.9±6.5Ma(95％置信度,MSWD =0.71),加权平均年龄为238.5±3.7Ma(95％置信度,MSWD=5.8).其中,最小的辉钼矿Re-Os年龄与矿区内斑状花岗岩年龄(227.6±1.3Ma)一致,表明成岩和成矿作用发生在三叠纪.7件辉钼矿样品Re含量为26.51×10-6～91.34×10-6,指示成矿物质主要来自古生代增生作用形成的不成熟大陆壳.已有成矿年龄显示了印支期成矿事件在东天山地区非常显著,发生于大陆碰撞造山体制.     

Rb-Sr Dating of Pyrite and Quartz Fluid Inclusions and Origin of Ore-forming Materials of the Jinshan Gold Deposit,Northeast Jiangxi Province,South China

The Jinshan gold deposit is located in the Northeast Jiangxi province,South China,which related to the ductile shear zone.It contains two ore types,i.e.the alteration-type ore and the goldbearing quartz vein ore.Rb-Sr age dating is applied to both gold-bearing pyrite in the alteration-type ore and fluid inclusion in the gold-bearing quartz vein to make clear the time of the gold mineralization of the Jinshan deposit.Analytical results of this study yielded that the age of the alteration-type ore bodies is about 838±110Ma,with an initial 87Sr/86Sr value of 0.7045±0.0020.However,the age of the gold-bearing quartz vein-type ore is about 379±49Ma,and the initial 87Sr/86Sr is 0.7138±0.0011.Based on the age data from this work and many previous studies,the authors consider that the Jinshan gold deposit is a product of multi-staged mineralization,which may include the Jinninian,Caledonian,Hercynian,and Yanshanian Periods.Among them,the Jinninian Period and the Hercynian Period might be the two most important ore-forming periods for Jinshan deposit.The Jinninian Period is the main stage for the formation of alteration-type ore bodies,while the Hercynian Period is the major time for ore bodies of gold-bearing quartz vein type.The initial values of the 87Sr/86Sr from this study,as well as the previous isotope and trace element studies,indicate that the ore-forming materials mainly derived from the metamorphic wall rocks,and the ore-forming fluids mainly originated from the deep metamorphic water.     

广西大厂拉么锌铜多金属矿床成岩成矿作用年代学研究

本文对广西大厂矿田拉么矿区内出露的酸性侵入岩和矿石进行了精细的年代学研究,分别获得龙箱盖含斑黑云母花岗岩锆石原位SHRIMP UPb和全岩RbSr等时线年龄为94±4Ma（95%可信度）和98.6±1.9Ma（95%可信度）,矽卡岩成矿期锌铜矿石中石英矿物RbSr等时线年龄为98.6±6Ma（95%可信度）。上述测定结果表明,拉么锌铜多金属矿床的成矿年龄与相关岩体的成岩年龄接近,均形成于早白垩世晚期。     

Rb–Sr Dating of Gold‐Bearing Pyrite in the Jinchang Porphyry Cu–Au Deposit,Heilongjiang Province,NE China

The Jinchang Cu–Au deposit in Heilongjiang Province, NE China, is located in the easternmost part of the Central Asian Orogenic Belt. Rb–Sr analyses of auriferous pyrite from the deposit yielded an isochron age of 113.7 ±2.5 Ma, consistent with previously reported Re–Os ages. Both sets of ages represent the timing of Cu–Au mineralization because (i) the pyrite was separated from quartz–sulfide veins of the mineralization stage in granite porphyry; (ii) fluid inclusions have relatively high Rb, Sr, and Os content, allowing precise measurement; (iii) there are no other mineral inclusions or secondary fluids in pyrite to disturb the Rb–Sr or Re–Os decay systems; and (iv) the closure temperatures of the two decay systems are ≥500°C (compared with the homogenization temperatures of fluid inclusions of 230–510°C). It is proposed that ore‐forming components were derived from mantle–crust mixing, with ore‐forming fluids being mainly exsolved from magmas with minor amounts of meteoric water. The age of mineralization at Jinchang and in the adjacent regions, combined with the tectonic evolution of the northeast China epicontinental region, indicates that the formation of the Jinchang porphyry Cu–Au deposit was associated with Early Cretaceous subduction of the paleo‐Pacific Plate.     

东天山康古尔塔格金矿带年代学研究

康古尔塔格金矿带分布于东天山石炭系中、下统火山岩区,近年来发现了浅成低温热液型、韧性剪切带型和石英脉型3种成因类型的金矿。经Rb-Sr等时线法、U-Ph法、⁴⁰Ar/³⁹Ar法等地质年代学研究,认为容矿岩石火山岩的年龄为300-280Ma;矿化发生在海西晚期到印支早期(270-220Ma),经历了多期次的成矿作用;各矿区的花岗质侵入岩与成矿有一定的时空关系。     

江南过渡带东至查册桥金矿床~(40)Ar-~(39)Ar年代学及成矿条件研究

查册桥金矿是近年来在江南过渡带发现的一个金多金属矿床,本文对该矿床与矿化有关的蚀变花岗闪长斑岩中绢云母进行了~(40)Ar-~(39)Ar年龄测试,获得蚀变岩金矿石绢云母坪年龄156.9±1.6 Ma,等时线年龄152±28 Ma和矿化强蚀变花岗闪长斑岩绢云母坪年龄142.1±1.3 Ma,等时线年龄137±13 Ma。程檀矿段与牛头高家矿段流体包裹体均一温度为160℃左右,氢氧同位素特征显示成矿热液以岩浆热液为主。结合本区及邻近矿区相关研究成果,本区金矿主要为浅成、低温型,成矿物质和热液具有多来源特征,原生金矿以微细粒浸染型为主,具类卡林型金矿矿化特征,其年龄值分别对应于燕山期不同阶段构造活动和成岩成矿作用时代,其成矿过程经历了中侏罗世韧-脆性挤压构造变形和蚀变、矿化,晚侏罗世-早白垩世早期与岩体侵入相关的金多金属矿化,以及早白垩世中、晚期浅成低温热液成矿作用。     

东天山马头滩金矿的成矿时代及其地质意义

马头滩金矿区位于秋格明塔什—黄山韧性剪切带西段南缘,矿床成因研究表明,马头滩金矿的形成受该韧性剪切带的控制。为探讨马头滩金矿的成矿时代及其地质意义,开展了石英流体包裹体成分及Rb-Sr、白云母Ar-Ar和硫化物S同位素分析。石英的Rb-Sr同位素等时线年龄为258.8±6.8Ma,限定了该矿床的形成时代,40Ar-39Ar坪年龄为256.0±1.0Ma,与成矿作用及秋格明塔什韧性剪切带西段右行走滑剪切变形作用在误差范围内一致,说明成矿作用与走滑剪切作用密切相关。S同位素及石英包裹体气液相成分特征表明,成矿流体具有幔源特征,并有壳源物质参与,而由右行走滑剪切及随后的抬升作用导致的压力和温度的降低应是东天山地区剪切带型金矿床形成的动力学背景。     

东天山土屋–延东铜矿带石英钠长斑岩与辉钼矿形成年龄及其重要意义

土屋–延东铜矿带位于东天山大南湖–头苏泉岛弧带上,是目前新疆最大的铜矿带。铜矿体主要赋存于石炭纪斜长花岗斑岩和晚古生代企鹅山群中,但是前人研究表明斜长花岗斑岩的成岩年龄(339~332 Ma),明显老于成矿年龄(约322Ma),因此,土屋–延东铜矿带的致矿岩体至今还存有争议。本次研究首次对该铜矿带晚石炭世石英钠长斑岩进行了详细的岩相学和LA-ICP-MS锆石U-Pb年代学分析,并结合辉钼矿Re-Os同位素年龄测定,探讨土屋–延东铜矿带矿床成因。对延东铜矿4件辉钼矿样品进行Re-Os同位素分析,得到322.0±2.7 Ma的加权平均模式年龄和319.1±9.1 Ma等时线年龄,明显要晚于斜长花岗斑岩年龄。两个石英钠长斑岩样品LA-ICP-MS锆石U-Pb年龄分别为324.9±2.4 Ma和324.5±2.1 Ma,表明石英钠长斑岩为晚石炭世岩浆活动的产物。岩相学研究表明,石英钠长斑岩中发育黄铜矿+绿泥石+硬石膏+方解石矿物组合,这与延东铜矿主成矿阶段的矿物组合基本一致,并且石英钠长斑岩成岩年龄与辉钼矿年龄在误差范围内一致,表明石英钠长斑岩可能与土屋-延东铜矿带铜矿形成有着密切关系,这一发现可能为大南湖–头苏泉岛弧带晚石炭世铜矿的勘查提供新的思路。     

Permian copper–polymetallic mineralization in the southern Great Xing’an Range,Northeast China: the Daolundaba copper–polymetallic deposit example

The Daolundaba Cu–polymetallic deposit is a newly discovered Cu–W–Sn deposit on the western slopes of the southern Great Xing’an Range, and its mineralization was related to an early Permian coarse-grained biotite granite. However, there is little information on the age of formation of the deposit. In this article, we present the results of our investigation into the age of the Daolundaba Cu–polymetallic deposit, which involved the selection of chalcopyrite and pyrrhotite samples for Rb–Sr isochron dating. A Rb–Sr isochron defined by the chalcopyrite samples yielded a Rb–Sr isochron age of 290.0 ± 11 Ma (MSWD = 1.2) with an initial Sr isotopic composition (I_Sr) of 0.71446. The pyrrhotite samples yielded a Rb–Sr isochron age of 283.0 ± 2.6 Ma (MSWD = 1.16) with an initial Sr isotopic composition (I_Sr) of 0.71447. The Rb–Sr isochron age determined from the chalcopyrite and pyrrhotite is 282.7 ± 1.7 Ma (MSWD = 1.13). These results indicate that the Daolundaba Cu–polymetallic deposit formed during the early Permian (282.7–290.0 Ma). The Rb and Sr contents of the chalcopyrite and pyrrhotite range from ~0.1325 to ~3.6810 ppm and from ~0.1219 to ~9.5740 ppm, respectively, and the initial Sr isotope ratios (I_Sr) range from 0.71047 to 0.71869, with an average of 0.714723. These isotopic characteristics indicate the ore-forming minerals of the Daolundaba Cu–polymetallic deposit originated mainly from the crust, but with small amounts of mantle material involved. The copper was derived from the associated magma whereas the W and Sn was derived from the surrounding strata. The Permian mineralization of the Xing’an–Mongolia region occurred in an active continental margin setting during subduction of the Palaeo-Asian oceanic plate beneath the Siberian Plate.     

Rb–Sr Dating of Gold‐bearing Pyrites from Wulaga Gold Deposit and its Geological Significance

Wulaga epithermal gold deposit is located in northeast China. Gold mineralization mainly occurs within the crypto‐explosive breccia belt of subvolcanic intrusion. Constraints on the precise timing of mineralization are of fundamental importance for understanding the ore genesis of the Wulaga gold deposit and its mineralization potential. Three hydrothermal stages have been identified: the early veiny quartz–euhedral pyrite stage; the fine pyrite–marcasite–gray or black chalcedony stage; and the late carbonate–pyrite stage. The Rb–Sr dating of gold‐bearing pyrites from the fine pyrite–marcasite–gray or black chalcedony stage is 113.8 ± 4.4 Ma with an initial ⁸⁷Sr/⁸⁶Sr ratio of 0.706346 ± 0.000019. The age of the gold deposit is consistent with the age of ore‐bearing volcanic (109–113 Ma) and subvolcanic intrusion (103–112 Ma) within the error limits, and the pyrite initial ratio has an identical value of ⁸⁷Sr/⁸⁶Sr to subvolcanic intrusion (0.705547 ± 0.000012). These indicate that crystallization of the wall rock and epithermal gold mineralization was coeval and likely cogenetic. Moreover, a lot of epithermal gold deposits that formed in Early Cretaceous volcanic and subvolcanic intrusions have been discovered in recent years in Heilongjiang province. Combined with the studies of tectonic and magmatic activities, we propose that the formation of the Wulaga gold deposit might be caused by the heated circum‐flow water related to the volcanic–subvolcanic intrusive hydrothermal event triggered by the ancient subduction of the Izanagi plate in the Early Cretaceous.     

新疆元宝山金矿床锆石U-Pb、全岩Rb-Sr年代学及其地质意义

元宝山金矿床位于新疆鄯善县境内,属于东天山康古尔塔格金矿带,受秋格明塔什-黄山韧性剪切带控制。为探讨元宝山金矿床的成矿时代及其地质意义,本次研究开展了矿石石英Rb-Sr年代学、含矿围岩Rb-Sr、Sm-Nd及锆石U-Pb同位素年代学分析。(255.6±1.0)Ma的含矿围岩Rb-Sr同位素等时线年龄以及(256±14)Ma的石英Rb-Sr等时线年龄,限定了该矿床的形成时代,而(334.7±9.8)Ma的含矿围岩锆石U-Pb年代学数据表明,该矿床的含矿围岩为中石炭统。Sr、Nd同位素特征表明,成矿物质来源具有幔源特征并有壳源物质参与,而区内韧性剪切带右行走滑剪切及随后的抬升作用导致的压力和温度的降低应是元宝山金矿床形成的动力学背景。     

Auriferous Quartz Veins from the Dongping Gold Deposit,NW Hebei Province and Metallogenesis—Fluid Inclusion Rb—Sr Isochron Evidence

The Dongping gold deposit, situated on the northern margin of the North China Platform, is a composite deposit composed of auriferous quartz vein-type and altered rock-type ore bodies. It is hosted in the inner contact zone of an alkaline intrusion which was intruded into Archean metamorphic rocks and was formed not later than the Hercynian period. Auriferous quartz veins of the deposit are dated with the fluid inclusion Rb-Sr isochron method at 103 ± 4 Ma, indicating that the gold deposit was formed in the Yenshanian period.⁸⁷Sr/⁸⁶Sr sourcetracing shows the ore forming materials came dominantly from alkaline intrusions. These results, combined with other isotope and REE data, suggest that the Dongping gold deposit is not a traditional magmatic hydrothermal deposit, but a reworked hydrothermal deposit related to heated and evolved meteoric water. This project (49372105) is financially supported by the National Natural Science Foundation of China.     

云南个旧锡矿的成矿时代

云南个旧锡矿经历了印支期海底基性火山——沉积成矿、海底喷流——沉积成矿和燕山晚期的花岗岩叠加改造成矿的作用。用Ar-Ar、K-Ar和Pb-Pb法分析了3个成矿系列的成矿年龄,结果表明,成矿系列Ⅰ的Ar-Ar法坪年龄和等时线年龄为95.93±5.41～123.91±15.41Ma,K-Ar法表观年龄为112.50±2.25Ma,普通铅法年龄为210～240Ma;成矿系列Ⅱ的Ar-Ar法坪年龄和等时线年龄为191.81±2.26～205.11±4.38Ma,K-Ar法表观年龄为186.01±3.72Ma,普通铅法年龄为200～230Ma;成矿系列Ⅲ的Ar-Ar法坪年龄和等时线年龄为83.23±2.07～85.22±2.38Ma,K-Ar法表观年龄为43.49±0.87Ma,普通铅法年龄为83～116Ma。