天山东段凌东金矿床地质、S-Pb-Os同位素示踪和Re-Os测年  

Geology,S-Pb-Os isotopic compositions and Re-Os dating of the Lingdong gold deposit in the eastern Tien Shan

作　　者：王雪峰[1] 黄勇森 陈刚 高俊宝 

机构地区：[1]地质过程与矿产资源国家重点实验室,中国地质大学地球科学与资源学院,北京100083 [2]新疆地质矿产局第一地质大队,昌吉831100

出　　处：《岩石学报》2016年第5期1409-1419,共11页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(U1303292);国家科技支撑计划(2011BAB06B02);中国地质调查项目(121211220926)联合资助

摘　　要：在天山西段,南天山北缘褶皱冲断带发现包括Muruntau在内的众多世界级金矿床,构成＂亚洲金腰带＂的主体;而在天山东段,南天山北缘褶皱冲断带却少有重要金矿发现,凌东金矿是在该区域新发现的一处重要金矿床,勘探工作正在进行,矿石金品位3.5g/t。金矿体呈透镜状产于下泥盆统阿尔彼什麦布拉克组变晶屑凝灰岩中,受眼形山脆韧性剪切带中的张扭性断裂-裂隙控制。自然金主要以粒间金、包裹金和纳米金形式赋存于黄铁矿、磁黄铁矿粒间和包裹于晶体内部。含金黄铁矿Re-Os法测得成矿年龄306.0±2.4Ma（MSWD=0.54）,与南天山洋关闭后陆陆碰撞造山的时代相近,反映凌东金成矿与造山过程中的脆韧性变形密切相关。金矿石δ34S值为2.9‰~6.5‰,与下泥盆统阿尔彼什麦布拉克组凝灰岩围岩δ34S值（3.3‰~6.6‰）近乎一致,指示矿石硫主要源于容矿的火山-沉积地层。含金黄铁矿Pb同位素组成（206Pb/204Pb=17.160~17.483,207Pb/204Pb=15.369~15.736,208Pb/204Pb=35.749~38.879）和Os同位素（187Os/188Os（i）=0.680±0.039）共同指示金成矿物质部分是变质流体从深部带来,部分源于容矿的火山-沉积地层。凌东金矿床是陆陆碰撞强烈变形动力学背景下脆韧性变形带容矿的造山型金矿床,这类金矿床在天山东段南天山北缘褶皱冲断带具有良好找矿前景,值得高度关注。Much more world-class gold deposits,which are the main part of the ＂Asian Gold Belt＂,have been found along the northern margin folding-thrusting fault zone of southern Tien Shan in the western region of Tien Shan. But few are found along that in the eastern region of Tien Shan. The Lingdong gold deposit with gold grade of 3. 5g / t. is a new-discovered and explorating important deposit along the zone in the eastern region of Tien Shan. The gold orebody occurs as lense hosted in tension-shear faulted crystal tuff of Early Devonian in the Yanxingshan brittle-ductile shear zone. The gold occurrence in ores is intergranule-,included-and nanometregold mainly in pyrite and pyrrhotite. Re-Os dating of the gold-bearing pyrite obtains a mineralization age of 306. 0 ± 4. 2Ma,which is almost consistent with the collision orogenic age after the closing of the southern Tien Shan Ocean. The gold mineralization might be closely related to the brittle-ductile deformation during the orogenic processes. The ore δ34S ranges from 2. 9‰ to 6. 5‰,that is close to the tuff δ34S（ from 3. 3‰ to 6. 6‰）,indicating that the ore sulpher was derived from the tuff. The Pb isotopic compositons（206Pb /204 Pb = 17. 160 ~ 17. 483,207 Pb /204 Pb = 15. 369 ~ 15. 736,208 Pb /204 Pb = 35. 749 ~ 38. 879） and the187 Os /188Os（ i）（ 0. 680 ± 0. 039）of the gold-bearing pyrite in the ores indicate that the metal was sourced partially from deep reservoir by metamorphic fluids and partially from hosted tuff. The Lingdong gold deposit is a brittle-ductile shear zone hosted orogenic gold deposit mineralizing under collision deformation setting. The orogenic gold deposit is showing a better exploration prospect along the northern margin foldingthrusting fault zone of southern Tien Shan in the eastern region of Tien Shan and should be paid much more attention.

关 键 词：凌东金矿 脆韧性剪切带 S-Pb同位素示踪 RE-OS测年 天山 

分 类 号：P618.51[天文地球—矿床学]