云南省香格里拉县甭哥碱性杂岩体岩石地球化学特征及其地质意义  

Petrographic and geochemical characteristics for Bengge alkaline igneous complex and its geological significance in Shangri-La,Yunnan,China

作　　者：黄玉蓬[1,2] 刘显凡[1] 邓江红[1] 赵甫峰[1] 夏德伟[2] 陈浩[1,2] 

机构地区：[1]成都理工大学地球科学学院,成都610059 [2]四川省冶金地质勘查局成都地质调查所,成都610203

出　　处：《岩石学报》2017年第2期622-638,共17页Acta Petrologica Sinica

基　　金：中国地质调查局地调项目(1212011120587);国土资源部构造成矿成藏重点实验室(成都理工大学);国家自然科学基金项目(41403025)联合资助

摘　　要：云南省香格里拉地区发育一套以甭哥碱性杂岩体为代表的富碱高钾岩浆岩。该岩体SiO_2变化范围较宽,高FeO^T和碱质,低Al_2O_3、MgO和CaO;富集LILE和LREE,相对亏损HFSE并显著亏损Cr、Co、Ni等过渡族元素,同时还具有从弱负异常至强正异常的δEu及δCe,表现出埃达克质与岛弧型火山岩双重特征。岩石地球化学研究表明,甭哥岩体并非单一岩浆经简单结晶分异而来,其岩浆来源具有多样性与多期性,它们主要代表了晚三叠印支期俯冲洋片和地幔楔与下地壳部分熔融及新生代含金云母相的交代富集地幔低程度部分熔融的岩浆作用。其形成和演化大致经历了晚印支期初始岩浆形成和燕山期后续岩浆逐步叠加及新生代喜山期岩浆侵位三个阶段,在整个岩浆作用过程中,伴随有地幔流体交代作用及由此引发的壳幔物质混染现象。而与甭哥碱性杂岩体有关的金成矿作用主要受制于该区多阶段岩浆与含矿地幔流体的相互作用及地幔流体交代叠加混染作用,其金成矿的富矿体可能定位于深部,据此提出甭哥碱性杂岩体具有深部成矿的勘探开发远景。It is development a suit alkali-rich and high-K igneous that are represented by Bengge alkaline complex igneous in Shangri-La area,Yunnan Province. The intrusion has a wide range of SiO_2 content,higher FeO^T and alkali while lower Al_2O_3,MgO,CaO content; and enriched in LILE and LREE,depleted in HFSE relatively while transition elements significantly such as Cr,Co,Ni.And it also has the anomaly from weak negative to strong positive with δEu and δCe,and shows characteristics of both adakitic and island arc volcanic rocks with trace elements. The study of petro-geochemistry suggests the Bengge intrusion is not the product of simple crystallization differentiation of single magma. Its magma resources are diversity and multi-period,and they mainly represented the magmatism of subduction oceanic slab and mantle wedge and low-crust partial melting in Late Triassic Indosinian and phlogopitebearing metasomatic enrichment mantle partial melting with a low degree in Cenozoic. The formation and evolution of Bengge intrusion had roughly undergone three stages that are formation of initial magma in Late Indosinian,superimposing of subsequent magma in Yanshanian and magma emplacing in Himalayan,and with mantle fluid metasomatism and crust-mantle materials contamination caused by the former in the whole magmatism process. And the gold mineralization related to Bengge alkaline complex igneous is mainly subject to the multi-period magma interacting with ore-bearing mantle fluid and mantle fluid metasomatic superimposing contamination.The bonanza of the gold mineralization may be located in deep. And according this,we suggest that the Bengge alkaline complex igneous has a deep metallogenic prospect of exploration and development.

关 键 词：甭哥碱性杂岩体 多期岩浆作用 地幔流体交代 壳幔物质混染 香格里拉 

分 类 号：P588.15[天文地球—岩石学]