滇西北北衙金多金属矿田的成岩成矿作用：对印-亚碰撞造山过程的响应  

Petrogenesis and metallogenesis of the Beiya gold- polymetallic ore district,northwestern Yunnan province,China: Responses to the Indo-Asian collisional processes

作　　者：薛传东[1,2] 侯增谦[2] 刘星[1] 杨志明[2] 刘勇强[1] 郝百武[1] 

机构地区：[1]昆明理工大学地球科学系,昆明650093 [2]中国地质科学院地质研究所,北京100037

出　　处：《岩石学报》2008年第3期457-472,共16页Acta Petrologica Sinica

基　　金：国家基础研究计划“印度-亚洲大陆主碰撞带成矿作用”973项目综合课题(编号:2002CB4126);国家自然科学基金项目(编号:40772067);云南省自然科学基金项目(编号:2006D020M);云南省省院省校科技合作项目(编号:YK98008-2)资助

摘　　要：北衙金多金属矿田是藏东-金沙江-哀牢山新生代富碱斑岩成矿带中南段的代表性矿床之一,发育一个与富碱斑岩密切相关的金多金属成矿系统。本文较为系统地分析了矿田内的成岩成矿作用特征及其演化过程,并探讨其与印-亚碰撞造山过程的响应关系。富碱斑岩具有埃达克岩的地球化学亲合性,其源区是喜马拉雅期印-亚碰撞造山造成的软流圈向东挤出汇聚使大规模走滑断裂活化,诱发玄武质下地壳部分熔融的壳幔过渡层,成岩年龄可分为第一期(65～59Ma)、第二期(36～32Ma)、第三期(26～24Ma)和最晚期(3.8～3.6Ma)等4期,其中第二、三期与富碱岩带北段的两期岩浆集中活动时期基本吻合,形成的斑岩对金多金属成矿较为有利。区内金多金属矿床可划分为三个矿床类型和七个矿床亚类,即与喜马拉雅早—中期斑岩有关的金多金属矿床(Ⅰ),包括接触带夕卡岩型、斑岩型和热液充填型(及熔浆型)金多金属矿床;与喜马拉雅第三期斑岩有关的金多金属矿床(Ⅱ),包括爆破角砾岩型和叠加热液改造型金多金属矿床;以及与喜马拉雅期表生作用有关的风化堆积型金矿床(Ⅲ),包括古砂矿型和红色粘土型金矿床。Ⅰ、Ⅱ类型矿床受富碱斑岩及伴生的 NE 到 NNE 向断裂控制,赋存于富碱斑岩体内、内外接触带及其附近围岩的层间破碎带或构造裂隙带中,在成因和空间上与斑岩及隐爆角砾岩等密切有关。成矿物质和成矿流体主要来源于地幔,围岩地层只是提供了成矿的空间,不同类型的矿体之间呈"贯通式"的时间和空间关系,构成了一个统一的喜马拉雅期富碱斑岩-热液型金多金属成矿系统。先期形成矿床明显受后期岩浆热液的叠加改造,但矿化分布和成矿元素组合仍表现为以斑岩为中心,存在 CuAu(Mo)多金属→FeCuAuPbZn 多金属→AuPhZnAg 多金属的分带特征。从最早期含金铁矿床形成之后,原�Beiya gold-polymetallic ore district found in northeastern Yunnan province in the last few years, located in the middlesouthern section of the eastern Xizang-Jinsha River - Ailao Mountain alkali-rich porphyry metallogenetic belt, is one of the typical gold-polymetallic metallogenesis system related to alkali-rich intrusion during the Himalayan epoch. Based on the previous researches and the extensive field investigations from the recent scientific programs, this article systematically studies the petrogenesis, metallogenesis evolving sequence in the ore district and their responses to the Indo-Asian collisional processes. The main intrusion rock types including quartz-albite porphyry, quartz-K-feldspar porphyry and biotite-K-feldspar porphyry with adakitic magma affinity, which intruded during the period of 65 to 59 Ma, 36 to 32 Ma, 26 to 24 Ma and 3.8 to 3.6 Ma respectively. The magmas of ore-bearing alkali-rich porphyries were derived from mixed melting of the crust-mantle transitional layer in eastern margins of the Tibet plateau, and genetically related to the asthemosphere eastern-extruding and the large-scale strike-slip faulting due to the Himalayanian Indo-Asian collisional systems. The duration of the first episode and the second episode are consisted with the two concentrative petrogenesis episodes approximately. Within the ore district, three types and seven subclasses of gold-polymetallic deposits have been recognized, there are （Ⅰ） porphyry copper-gold-polymetallic deposits related to the first and second stage of alkali-rich porphyry intrusion, including skarn-type gold-polymetallic deposits （including magma-type ）, porphyry-type copper-gold deposits and hydrothermal-type gold- polymetallic deposits, （Ⅱ） porphyry-related hydrothermal-type gold-polymetallic deposits due to the third stage of alkali-rich porphyry intrusion, including cryptoexplosive breccia-type gold-ferrous-lead- zinc-polymetallic deposits and hydrothermal superimposed-type gold-polymetallic deposits, and （Ⅲ） we

关 键 词：成岩成矿作用 富碱斑岩 印.亚陆陆碰撞造山过程 喜马拉雅期 北衙金多金属矿田 滇西北 

分 类 号：P611[天文地球—矿床学] P612[天文地球—地质学]