特提斯西段塞尔维亚?ukaru Peki超大型斑岩-浅成低温型铜金矿床的热液蚀变和硫化物分带特征及其找矿方向

Hydrothermal Alteration and Sulfide Zoning Characteristics of theČukaru Peki Super-large Porphyry-epithermal Copper-gold Deposit in Western Tethys,Serbia and its Implication for Exploration

查明蚀变和硫化物分带特征是建立斑岩-浅成低温铜金成矿系统的矿床模型与找矿预测的关键。?ukaru Peki铜金矿床是特提斯西段塞尔维亚Timok矿集区近几年新发现的超大型斑岩-浅成低温热液型铜金矿床(上部矿带资源量铜154万吨@2.45%,金86吨@1.37 g/t;下部矿带资源量铜1428万吨@0.83%,金295吨@0.17 g/t),矿体主要产于晚白垩世安山岩中。目前关于该矿床热液蚀变与矿化分带特征及其找矿方向的研究程度相对较低,本文根据钻孔编录信息,利用短波红外(SWIR)光谱技术、光学显微镜和电子探针分析技术,对典型剖面钻孔中的岩矿石样品开展研究,厘定了?ukaru Peki铜金矿床的热液蚀变和金属硫化物分带特征。研究发现该矿床具有垂向分带特征:下部斑岩铜金矿体、中部斑岩-浅成低温过渡铜金矿体和上部高硫型浅成低温热液铜金矿体。矿区热液蚀变分带特征明显,其中斑岩铜金矿体以岩体为中心,由内向外可划分为钾硅酸盐化带、青磐岩化带、绿泥石-白云母带和石英-白云母带,绿泥石-白云母带中的白云母SWIRAl-OH 2200nm吸收峰波长高于石英-白云母带;斑岩向浅成低温过渡铜金矿体发育硬水铝石-叶蜡石带;高硫型浅成低温铜金矿体发育高级泥化蚀变,由内向外可划分为石英-明矾石带、地开石-高岭石带和蒙脱石带。?ukaru Peki铜金矿床的金属硫化物组合具有明显的分带特征,斑岩铜金矿体由下至上表现为:黄铜矿+斑铜矿→黄铁矿+黄铜矿+(磁铁矿±赤铁矿);过渡铜金矿体主要为:砷黝铜矿+(斑铜矿+黄铜矿+蓝辉铜矿+铜蓝)组合;高硫铜金矿体为硫砷铜矿+铜蓝组合。总体上,矿床下部为Cu-Fe-S体系,中部贯穿Cu-As-Sb-S体系,向上转变为Cu-S体系。硫化物组合从深部早阶段的高温低硫化态转为中浅部晚阶段的低温高硫化态。结合化探分析资料,建立热液蚀变和硫化物分带模型,推测?ukaru Peki铜金矿床北西部存在很大的找矿潜力。?ukaru Peki铜金矿床的研究可以为我国紫金山金铜矿床深边部增储、冈底斯成矿带寻找晚白垩世斑岩-浅成低温热液铜金矿床提供一定参考。

The zoning characteristics of alteration and mineralization are the key to establish the deposit model and prospecting prediction of the porphyry-epithermal copper-gold metallogenic system.TheČukaru Peki is a newly discovered giant porphyry-epithermal copper-gold deposit(upper zone:copper 1.54 million tons@2.45%,gold 86 t@1.37 g/t,lower zone:copper 14.28 million tons@0.83%,gold 295 tons@0.17 g/t)in Timok,Serbia,Western Tethys.The orebodies are mainly hosted in the late Cretaceous plagioclase andesite,and research on its alteration and mineralization zoning characteristics and prospecting potential is rare.In this paper,we integrated drill hole logging with short-wavelength infrared(SWIR)spectral analysis,microscopic observation,and sulfide EMPA results of rock and ore samples,and the characteristics of hydrothermal alteration and sulfide zoning were determined,and its implication for exploration was discussed.We found that the deposit has zoning characteristics of high-sulfidation epithermal copper-gold mineralization in the upper part,transitional copper-gold mineralization in the middle part,and porphyry copper-gold mineralization in the lower part.The zoning characteristics of hydrothermal alteration in the mining area are apparent.The porphyry intrusion is the centre of the porphyry-type copper-gold mineralization,and potassic alteration zone,propylitic alteration zone,chlorite-white mica zone,and quartz-white mica-zone are developed sequentially outwards.The wavelength of the white mica SWIR Al-OH 2200 nm peak position in the chlorite-white mica zone is generally higher than that in the quartz-white-mica zone.The transitional mineralization develops diaspore-pyrophyllite alterations and dickite-kaolinite superimposed with phyllic alterations.The upper high-sulfidation epithermal copper-gold mineralization develops advanced argillic,which can be divided into quartz-alunite,dickite-kaolinite and montmorillonite from inside outside.Metallic mineral assemblages also have prominent zoning characteristics:the deep to shallow zonation of chalcopyrite+bornite→chalcopyrite+pyrite+(magnetite±hematite)for the lower porphyry copper-gold mineralization;the mainly tennantite+(bornite+chalcopyrite+digenite+covellite)for the transitional copper-gold mineralization;enargite+covellite for the upper high-sulfidation epithermal copper-gold type mineralization.Overall,the lower part of the ore deposit is a Cu-Fe-S system,the middle part runs through the Cu-As-Sb-S system,and it transforms upwards into a Cu-S system.The sulfide assemblage changes from the high-temperature and low-sulfidation state in the deep early stage to the low-temperature and high-sulfidation state in the mid-shallow at the late stages.In summary,combined with the geochemical data,we established a hydrothermal alteration and sulfide assemblage zoning model and speculated that there is an excellent mineralization potential in the northwestern and deep part of theČukaru Peki copper-gold deposit.This model presented may have important implications for deep exploration of the Zijinshan gold-copper deposit and late Cretaceous porphyryepithermal copper-gold deposits in the Gangdise metallogenic belts.