作　　者： ; ; ; ; ; ; ; ;

机构地区： 中国地质大学地球科学学院地质过程与矿产资源国家重点实验室

出　　处： 《岩石学报》 2010年第6期1633-1645,共13页

摘　　要： 同时开展成矿作用及成矿后变化保存两方面研究,是提高矿产预测能力的迫切需求。滇西新生代富碱斑岩型金多金属矿床除与喜马拉雅期富碱斑岩有密切的时空和成因关系外,另一个显著特点是发生了强烈的次生富集作用,是开展成矿系统变化与保存研究的天然实验室。含矿斑岩为一套以富碱(K2O+Na2O>8%)为特征的从基性到中酸性的岩石系列,其源区为古特提斯构造演化过程中形成的富集地幔,并于新生代早期上升至壳幔混合带时遭受部分熔融。含矿斑岩主体形成于33～38Ma,大规模成矿作用集中于34±2Ma左右,它们的形成与构造动力体制转换过程中的壳幔物质强烈交换和构造变形密切相关,并可能受青藏高原物质向东逃逸和软流圈脉动隆起的联合制约。之后,发生了印度板块由前期逆时针旋转向顺时针旋转的转变、反向旋转板块的拖曳与斜向俯冲板块回退作用的综合效应,导致了滇西地区岩石圈伸展作用和多期左行和右行断裂走滑运动及强烈构造隆升的发生,诱发了亏损地幔减压熔融产生的板内高钾岩浆岩的就位、大规模热水流体活动,并叠加区域红土化作用,成矿系统遭受了强烈的变化与改造,金的表生成矿作用在矿床形成后即已开始,之后经历了多阶段的演化,有明显的穿时性。主要表现为矿床抬升或掩埋、矿体错切或错失、矿化叠加或次生富集、远距离迁移以及就近淋滤或贫化等。 The Cenozoic alkali-rich porphyry type gold-polymetallic deposits are not only closely related to the Himalayan alkali-rich porphyries in space and time,but also suffered strongly secondary enrichment,so that is the best natural laboratory of study metallogenic post-ore changes and preservation. The ore-bearing porphyry is characterized by a set of alkali-rich (K2O+Na2O>8%) rock that from basic to intermediate-acid,came from the enriched mantle that formed in the tectonic evolution process of Tethys,and suffered partial melting when up to boundary between crust and mantle in the Early Cenozoic. The main ore-bearing porphyry formed in 33~38Ma,the large-scale mineralization concentrated in 34±2Ma; both of them are related to crust-mantle exchange and structural deformation that in the process of tectonic dynamic system transformation,and also possible controlled by the eastward escape of Qinghai-Tibet Plateau and pulsating uplift of asthenosphere. Later,the India plate changed into clockwise rotation from previous counterclockwise rotation; the oblique reverse rotation and rollback subduction of India Plate led to lithosphere extension,multiple sinistral or right-lateral strike-slip movement,strongly tectonic uplift,emplacement of high-K magmatic that come from the depression melting of depleted mantle,large-scale fluid activities,and regional laterization. The ore-forming system suffered strongly post-ore changes and deformation,went through multiple metallogenic,and characteristiced by obvious diachronism. The supergene gold minerlization started after the formation of gold deposits.

关 键 词： 成矿系统 变化与保存 富碱斑岩 新生代 滇西

领　　域： [天文地球] [天文地球]