中亚构造域多期叠加斑岩铜矿化:以阿尔泰东南缘哈腊苏铜矿床地质、地球化学和成岩成矿时代研究为例  

The multiperiodic superimposed porphyry copper mineralization in Central Asian Tectonic Region:A case study of geology,geochemistry and chronology of Halasu copper deposit,Southeastern Altai,China.

作　　者：薛春纪[1,2] 赵战锋[1,2] 吴淦国[1,2] 董连慧[3] 冯京[3] 张招崇[1,2] 周刚[4] 池国祥[5] 高景岗[6] 

机构地区：[1]地质过程与矿产资源国家重点实验室 [2]中国地质大学(北京)地球科学与资源学院,北京100083 [3]新疆维吾尔自治区地质矿产勘查开发局,新疆乌鲁木齐830000 [4]新疆维吾尔自治区地质矿产勘查开发局第四地质大队,新疆阿勒泰836500 [5]加拿大里贾纳大学地质学系 [6]长安大学地球科学与资源学院,陕西西安710054

出　　处：《地学前缘》2010年第2期53-82,共30页Earth Science Frontiers

基　　金："十一五"国家科技支撑计划(2006BAB07B01-02;2007BAB25B05);高等学校学科创新引智计划(B07011);长江学者和创新团队发展计划(IRT0755);新疆地矿局综合研究项目

摘　　要：新疆青河县新近发现哈腊苏铜矿床,正在进行的勘探证实具有大型铜储量前景。它位于阿尔泰东南缘,靠近额尔齐斯构造变形带。这个区域经历了古生代中期的洋-陆俯冲、古生代晚期的陆-陆碰撞以及其后的陆内活化等地质过程。铜成矿与哪种地质地质过程有关受人关注,矿床成因也存在斑岩型、热液脉型和火山岩型等不同认识。哈腊苏铜矿区主要出露中泥盆统基性火山岩(含苦橄岩)及侵入其中的不同时期含铜蚀变斑岩体,包括花岗闪长斑岩、斑状花岗岩、石英二长斑岩和石英闪长斑岩等,斑岩SiO_2质量分数为57.24%～65.45%,其中花岗闪长斑岩δ^(18)O_(V-SMOW)=7.9‰～8.6‰,ε_(Nd)(t)=7.3～8.5(接近于MORB值),(^(87)Sr/^(86)Sr)_t=0.70383～0.70410(接近原始地幔值),暗示岩浆起源于地幔或下地壳。矿区含铜蚀变斑岩全岩矿化(Cu 0.2%),矿体(Cu 0.3%以上)呈透镜状和不规则分枝脉状,产状与斑岩体相仿,95%以上矿体产于斑岩体内。围岩蚀变从矿体到斑岩再到基性火山岩围岩,发育钾长石黑云母化、黑云母绿泥石化、青磐岩化的分带,后期脉状线型钾长石化叠加于早期面状弥散型钾硅酸盐蚀变之上。没有次生硫化物富集现象,原生铜矿石出现细脉浸染型和脉状叠加型两种自然类型,前者以"黄铁矿+黄铜矿+辉钼矿"为典型金属矿物组合,后者呈在前者背景上的"石英+黄铁矿+黄铜矿"脉状叠加矿化。相对于前者,后者Cu、Au品位明显偏高(分别达到Cu 2.21%、Au 0.83 g/t)、微量和稀土元素总量降低,微量元素蛛网图和REE配分曲线更为平缓,Eu正异常更加显著。基性火山喷发、幔源岩浆侵入和多期矿化叠加是哈腊苏铜成矿的关键,早期斑岩型铜成矿基础上的后期构造热液矿化叠加显著。细脉浸染型铜矿石中共生黄铁矿-黄铜矿的硫同位素温度计指示斑岩型铜成矿温度为420～560℃。铜矿石硫化物δ^(34)S_(V-CDT)�The Halasu copper deposit is recently discovered in Qinghe,Xinjiang,and proved to be a large-scale copper prospect by the exploration in progress.It is located at the southeastern Altai and near the Ertix tectonic deformation zone.The region had undergone the Middle Paleozoic ocean plate subduction,the Later Paleozoic continental collision and the successive intraplate activation processes.That which process was related to the copper ore mineralization has caused much attention,and there are debates on the metallogenesis of the ore,such as,porphyry copper type,hydrothermal copper vein-type and volcanic related copper deposit.The Middle Devonian basic volcanic rock（including picrites） and copper-bearing altered porphyry including granodiorite porphyry,porphyritic granite,quartz monzonite porphyry and quartz diorite porphyry of different periods crop out mainly in Halasu copper ore district.The porphyry＇s SiO2 content is from 57.24%to 65.45%; the granodiorite porphyry＇sδ（18）Ov-smow value is from 7.9‰to 8.6‰,itsε（Nd）（t） is from 7.3 to 8.5（near the value of MORB）,and（（87）Sr/（86）Sr）t is from 0.70383 to 0.70410（near the original mantle value）;these indicate a mantle or lower crust magma sources.The copper-bearing alteration porphyry is whole mineralized（Cu 0.2%）,the orebody（Cu over 0.3%） is lenticular and irregularly dendritic vein-shaped and its occurrence is similar to that of the porphyry,and over 95%of the orebodies are located within the porphyry.The wall-rock alteration developed in a sequence of the zones of K-feldspar-biotite,biotite-chlorite,to propylite from the ore-body to the porphyry and then to basic volcanic wall-rock,and the later veinlets of linear K-feldsparization overprinted on the earlier pervasive K-silicate alteration.There is no secondary sulfide enrichment,and the primary copper ores are of two natural types：the veinlet-disseminated and the vein-overprinted,the former is characterized by the typical metallic mineral association of pyrite-c

关 键 词：矿床地质 地球化学 U-PB法 Re-Os法 AR-AR法 斑岩铜矿 多期叠加矿化 哈腊苏 中亚 

分 类 号：P618.41[天文地球—矿床学] P597[天文地球—地质学]