新疆洪古勒楞铜矿床地质特征及构造背景

Geological and structure background characteristics of Hongguleleng copper deposit,Xinjiang

洪古勒楞铜矿床位于新疆西准噶尔西北部和布克赛尔县,属于谢米斯台-沙尔布提成矿带。地质剖面测量和岩相学研究表明,矿区出露地层为中奥陶统布鲁克其组火山-沉积岩,岩性以玄武岩和安山岩为主,其次为安山质角砾岩、安山质集块岩和晶屑凝灰岩,矿化与玄武岩、安山岩、安山质角砾岩相关;矿区断裂构造发育,矿体赋存其中;矿区围岩蚀变发育,从矿体到围岩可分为内、中、外3个带,各带的共生矿物组合为:绿泥石+绿帘石+石英+黄铜矿±闪锌矿组合、绿泥石+绿帘石±黄铜矿组合和绿泥石±方解石等,矿化程度与蚀变程度正相关;矿化类型包括浸染状、气孔充填状、角砾状、细脉状、块状矿化,矿石矿物主要为黄铜矿,脉石矿物主要为绿泥石、绿帘石。矿区的火山岩地球化学分析表明,矿区岩石分为2类:类型1为钙碱性系列玄武岩和安山岩,岩石稀土元素配分曲线呈右倾型,亏损Nb、Ta元素,富集LILE,w(Nb)低,形成于岛弧环境。类型2为拉斑-钙碱性系列玄武岩和安山岩,与类型1相似,亏损Nb、Ta元素,富集LILE,但是REE模式呈平坦型,w(Th)、Nb/Y值、Th/Yb值、Nb/Yb值较低,可能受洋脊俯冲影响。

The Hongguleleng copper deposit,located in Hebukesaier County,northwest of western Junggar,Xinjiang,belongs to the Xiemisitai-Shaerbuti metallogenic belt.Based on the study of the geological section and petrography,the authors detected that the strata of the ore district consist of volcanic-sedimentary rocks of the Bulukeqi Group comprising basalt and andesite with minor andesitic breccia,andesitic agglomerate and crystal fragment tuff.The mineralization is associated with basalt,andesite and andesitic breccia.The fault commonly occurs in the ore district and hosts the orebodies.Three alteration zones were identified from center to periphery in the ore district,which contain the mineral assemblage of chlorite ＋ epidote ＋ quartz ＋ chalcopyrite±sphalerite,chlorite ＋ epidote±chalcopyrite and chlorite±calcite.There is a positive correlation between alteration and mineralization.Disseminated,amygdale,brecciated vein and block ores constitute the main ore types.Chalcopyrite and chlorite-epidote are the main ores and gangue minerals in the Hongguleleng deposit,respectively.Based on whole-rock geochemistry,the authors recognized two rock types：type one is calc-alkaline basalt and andesite,with LREE and LILE enrichment and Nb and Ta depletion,indicating that they formed in a subduction zone;type two is tholeiitic to calcalkaline basalt and andesite,with same characteristics of type one,except for low Th content and low Nb/Y,Th/Yb,Nb/Yb ratios,indicating a possible ocean ridge-subduction influence.