班公湖-怒江成矿带南缘早白垩世俯冲背景铅锌矿床的发现及其勘查指示意义  

Discovery of Early Cretaceous skarn Pb-Zn deposit of subduction setting on southern margin of Bangong-Nujiang metallogenic belt and its exploration significance

作　　者：宋扬[1] 唐菊兴[1] 鲁洪涛 刘振宇[2] 李宝龙[1] 黄维平[2] 郑明 李发桥 李子琛 SONG Yang;TANG JuXing;LU HongTao;LIU ZhenYu;LI BaoLong;HUANG WeiPing;ZHENG Ming;LI FaQiao;LI ZiChen(MNR Key Laboratory of Saltlake Resources and Environment,Institute of Mineral Resource,Chinese Academy of Geological Science,Beijing 100037,China;Jilin Geological Survey Institute,Changchun 130000,Jilin,China)

机构地区：[1]中国地质科学院矿产资源研究所自然资源部成矿作用与资源评价重点实验室,北京100037 [2]吉林省地质调查院,吉林长春130000

出　　处：《矿床地质》2022年第3期527-542,共16页Mineral Deposits

基　　金：中国地质调查局项目(编号:DD20160026、DD20190167);国家自然科学基金项目(编号:42172100);基本科研业务费(编号:KK2107);自然资源部杰出青年人才培养计划(编号:KY-BR-XZ-202006)联合资助。

摘　　要：铅锌矿是西藏特色优势矿种之一,主要发育在冈底斯-念青唐古拉成矿带。班公湖-怒江成矿带虽与冈底斯-念青唐古拉成矿带南北相邻,但在铅锌找矿方面始终没有突破。近年来,班公湖-怒江成矿带铜多金属矿资源基地调查工作取得重要进展,其中,在班戈岩浆弧的外围发现了长给铅锌矿床。长给铅锌矿成矿类型为矽卡岩型,铅锌矿体赋存于石榴子石矽卡岩和石榴子石透辉石矽卡岩中,成矿作用可划分为矽卡岩、退化蚀变、石英-硫化物和方解石-硫化物4个阶段。矿石硫化物的S同位素在-2.5‰~+2.6‰之间,反映成矿物质来源与岩浆作用有关。与长给铅锌成矿事件有密切关系的花岗闪长斑岩锆石LA-ICP-MS U-Pb定年结果为(139.38±0.48)Ma(MSWD=0.41,n=25),与班戈岩浆弧早期活动一致,暗示成岩成矿与班公湖-怒江成矿带南缘早白垩世洋壳俯冲事件有关。在区域找矿方面,班公湖-怒江成矿带中段中生代存在中-晚侏罗世、早白垩世早期、早白垩世晚期、晚白垩世4期成矿作用,可能保存与班公湖-怒江洋壳俯冲有关的成矿系统。在矿区预测方面,判断长给矿床岩浆与围岩发生了较强烈的物质交换,成矿流体充足,且远端的矽卡岩尚未发现,建议下一步勘探工作仍以铅锌为主攻矿种,有望取得找矿新发现。Lead and zinc are Tibet’s preponderant mineral resources,mainly developed in the Gangdese-Nyainqentanglha metallogenic belt.The Bangong-Nujiang metallogenic belt has no breakthrough in Pb-Zn prospecting,although it is a neighbor of the Gangdese-Nyainqentanglha metallogenic belt.In recent years,a Pb-Zn discovery was made at Changji on the periphery of the Baga magma arc when undertaking the geological survey and Cu polymetallic exploration program covering the Bangong-Nujiang metallogenic belt.The mineralization at Changji is mainly skarn type,with Pb-Zn ore bodies occurring in garnet skarn and garnet diopside skarn.The mineralization can be divided into four stages:skarn formation,degenerative alteration,quartz-sulfide and calcitesulfide.The δ;S value of sulfide in ore are in the range of-2.5‰ to +2.6‰,suggesting a similar magmatic source of sulfur.The zircon U-Pb age of the mineralized related diorite porphyry is(139.38±0.48)Ma(MSWD=0.41,n=25),consistent with the early activities of the Baga magma arc.It implies that the mineralization was triggered by the oceanic crust subduction in the southern margin of the Bangong-Nujiang metallogenic belt during the Early Cretaceous.In terms of regional prospecting,four stages of mineralization,such as Middle-Late Jurassic,Early Cretaceous,Late-early Cretaceous,and Late Cretaceous,have been identified in the middle section of Bangong-Nujiang metallogenic belt.There may be more deposits related to the Bangong-Nujiang oceanic crust subduction.For prospect scale exploration,it is speculated that the amount of fluid and material of mineralization is sufficient to support the formation of a significant Pb-Zn deposit at Changji,especially the distal skarn has not been found yet.The paper suggests that the exploration should be still focused on Pb-Zn,the area is highly prospective to make new discoveries.

关 键 词：地质学 矽卡岩 铅锌矿 找矿勘查 长给 班公湖-怒江 西藏 

分 类 号：P618.42[天文地球—矿床学] P618.43[天文地球—地质学]