摘要
大兴安岭南段是我国北方最重要的锡矿带,本文对其时空分布和成矿规律进行了系统总结,并提出了大兴安岭南段锡多金属矿深部动力学模型和矿床模型,旨在推动区域进一步锡银找矿工作。研究表明,锡多金属矿形成于伸展构造环境,具有明显的成群分布特点,空间上夹持在二连—贺根山、黄岗—甘珠尔庙和西拉木伦深大断裂带之间,矿化时代集中在150~130 Ma之间,但在个别大中型矿床中表现出多期成矿的特征。尽管锡矿化规模巨大,但目前揭露的高分异含矿花岗岩体并不多见,成矿作用可能与该区高的成矿元素背景值有关,但同时矿体下部可能存在隐伏高分异岩体。锡多金属成矿系统以锡铅锌银为主,鲜有共生或伴生钨矿化,不同阶段或类型矿化是深部岩浆房多期次出溶的不同或相同性质流体共同作用的结果,同时成矿流体与围岩的反应也会影响流体的组成和演化。岩浆流体出溶、地层活化萃取、地幔物质、大气降水、热卤水和变质热液共同参与了成矿作用,尤其是深部镁铁质岩浆底侵及脱气不仅为成矿提供了热源,同时也可能提供了大量的成矿元素和挥发组分。在成矿过程中,流体温压的下降、不同来源流体混合、超临界流体不混溶作用、流体多次沸腾和水岩反应等是金属元素超常富集的主要机制。
The tin polymetallic ore belt of southern Great Xing’an Range(SGXR)is the most important tin ore belt in northern China.Here,aiming to promote regional tin/silver prospecting,we systematically summarized the spatiotemporal distribution and metallogenic characteristics and proposed the deep dynamics and metallogenic models of the tin polymetallic deposits in SGXR.These deposits were formed in an extensional environment,with obvious spatial and temporal aggregation characteristics.They are located between the Erlian-Hegenshan,Huanggang-Ganzhu’ermiao and Xilamulun fault zones and formed mostly between 150-130 Ma,although multi-stage mineralization likely occurred in some large and medium-sized ore deposits.Even though tin mineralization is extensive,few highly differentiated ore-bearing granites are exposed so far,due probably to high background of ore-forming elements in the area,but also likely they are hidden in the depth.The tin polymetallic ore is mainly composed of tin,lead,zinc and silver,with few concurrent or accompanied tungsten mineralization.Multi-stage,multi-type mineralization is a result of multi-stage magma extrusion from a deep magma chamber,which produced ore-forming fluids with similar or different properties.Meanwhile,reactions between ore-forming fluids and surrounding rocks could also affect the fluid composition and evolution.Magma fluid exsolution,stratigraphic activation and extraction,mantle material,atmospheric precipitation,hot brine and metamorphic hydrothermal fluid all played a part in mineralization.Especially in the high temperature,low pressure environment,deep mafic magma degassing not only provided heat source for the mineralization,but also might provide an abundance of ore-forming element and volatile component.During the mineralization process,the main contributing factors for the super enrichments of metal elements were decreasing fluid temperature/pressure,mixing of fluids from different sources,immiscibility of supercritical fluids,multiple boiling of the fluids and wate
作者
周振华
毛景文
ZHOU Zhenhua;MAO Jingwen(MNR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,CAGS,Beijing 100037,China)
出处
《地学前缘》
EI
CAS
CSCD
北大核心
2022年第1期176-199,共24页
Earth Science Frontiers
基金
国家重点研发计划项目(2019YFC0605202)
中央公益性科研院所基本业务费项目(YYWF201714)
国家自然科学基金项目(41772084,41302061,41820104010)
科技部基础资源调查专项项目(2017FY101300,2017FY1013002)。
关键词
锡多金属矿
时空分布
流体出溶
壳幔作用
超常富集机制
大兴安岭南段
tin polymetallic deposits
spatiotemporal distribution
fluid exsolution
crust-mantle interaction
super enrichment mechanism
southern segment of the Great Xing’an Range
