“三江”北段沱沱河地区的成矿规律与找矿方向  

Metallogenic regularity and ore exploration targeting in Tuotuohe area,northern Sanjiang orogenic belt

作　　者：宋玉财[1] 侯增谦[1] 王贵仁 李连松 杨天南[1] 张洪瑞[1] 刘燕学[1] 杨竹森[3] 田世洪[3] 刘英超[1] 贾宗涌 汪元奎 刘群 闫明 何利 

机构地区：[1]中国地质科学院地质研究所,北京100037 [2]青海省第五地质矿产勘查院,青海西宁810028 [3]中国地质科学院矿产资源研究所,北京100037

出　　处：《矿床地质》2015年第1期1-20,共20页Mineral Deposits

基　　金：国家重点基础研究规划项目(2009CB421008;2011CB403106);国家自然科学基金(41273050;41102040;41320104004);中国地质调查局地质大调查项目(12120114010301;1212011220908);中央级公益性基本业务费(J1314);国家科技支撑项目(2006BAB01A08)的联合资助

摘　　要：＂三江＂成矿带的北段沱沱河地区是中国首批整装勘查区之一,区域成矿规律和找矿方向亟待了解。研究表明,区内主要发育3期成矿事件,形成5种主要矿床类型。早期成矿发生在晚二叠世至早三叠世,为龙木错-双湖洋向北俯冲下的弧间或弧后盆地环境,形成开心岭火山岩容矿块状Fe（-Cu-Zn）矿床（VMS型）;第二期成矿作用发生于新生代40~25 Ma期间,对应印-亚大陆晚碰撞环境,形成那日尼亚与钾质火山岩岩浆活动有关的脉状PbZn矿床、扎日根玢岩型铁矿床及扎拉夏格涌与碱性斑岩有关的热液脉状Pb-Zn矿床;第三期矿化出现在新生代23Ma以来,对应印-亚大陆后碰撞环境,形成以茶曲帕查为代表的密西西比河谷型（MVT）Pb-Zn矿床。综合分析表明,区内应优先寻找MVT型矿床,在区域逆冲带的前锋带中,老于新生代的碳酸盐岩内、碳酸盐岩与碎屑岩地层界面附近是找矿的主要方向;晚二叠世至早三叠世及晚三叠世地层中双峰式火山岩建造是寻找VMS矿床的有利部位;新生代闪长玢岩分布区的正磁异常、Cu化探异常、发育绿帘石和绿泥石化的地区有利于寻找玢岩型铁矿床;而热液脉状Pb-Zn矿床的成矿潜力有限。Although the Tuotuohe area in northern Sanjiang orogenic belt is very important for the exploration of new mineral resources, the study of its metallogenic regularity and exploration targeting remains very insufficient. The authors have recognized five types of ore deposits that can be categorized into three epochs of mineralization with different geological settings. The first epoch occurred in Late Permian to Early-Triassic period when volcanics-hosted Kaixinling Fe（-Cu-Zn） deposit was formed in an intra- or back-arc basin during northward subduction of the Longmu Co-Shuanghu oceanic plate. The second epoch happened during about 40 Ma to 25 Ma when the continental crust in the area was thickened via India-Asian continental collision, and potassic volcanic magmatism-related Nariniya vein-type Pb-Zn deposit, Zarigen diorite porphyry Fe deposit, and alkali-rich porphyry-related Zalaxiageyong vein-type Pb-Zn deposit were formed. The third epoch took place after about 23 ~ 16 Ma, corresponding to a geological setting of extensional crust during India-Asian continental collision, during which the Chaqupacha MVT PbZn deposit was formed. The authors hold that the potential areas for exploring MVT deposits in the Tuotuohe area are pre-Cenozoic carbonates adjacent to the contact between the carbonate and clastic units in the front part of the Tanggula thrust system. To explore VMS deposits, it is crucial to discover Late-Permian to Early-Triassic and LateTriassic bimodal volcanic rocks. The Cenozoic diorite porphyry zones with positive magnetic anomalies, Cu geochemical anomalies, epidotization, and chloritization are potential targets for exploring the porphyry-related iron deposits. It is also considered that the exploration potential of the vein-type Pb-Zn deposits is very limited.

关 键 词：地质学 成矿特点 找矿方向 矿床类型 沱沱河 

分 类 号：P618.31[天文地球—矿床学] P618.42[天文地球—地质学]