摘要
东秦岭(即北秦岭造山带东段)是我国重要的稀有金属成矿区,产出约7000条伟晶岩脉体,集中分布于峦庄、官坡、龙泉坪和商南四个伟晶岩密集区。本文对东秦岭伟晶岩的空间分布特征、金属赋存状态、成矿时代、成矿条件及构造控矿要素进行了梳理,在前人研究基础上进一步总结了东秦岭稀有金属伟晶岩成矿规律。空间分布上,具有Li-Be等稀有金属矿化的伟晶岩在区域上多沿灰池子复式岩体以北的栾川-朱夏断裂和蔡川断裂分布,少量产出于在商丹缝合带北侧的商南地区(如大苇园、凤凰寨等),而并非以灰池子岩体为中心呈同心状分布。稀有金属伟晶岩形成时代为445~370Ma,尽管与东秦岭花岗岩形成时代存在交集(440~400Ma),但年代学数据和锆石Hf同位素组成表明东秦岭出露的花岗岩体并非众多稀有金属伟晶岩的母源花岗岩。锆石Hf同位素研究结果同时指示出,秦岭岩群可能通过深熔形成官坡、商南一带稀有金属伟晶岩。但商南富锂伟晶岩比官坡富锂伟晶岩具有较高锆石εHf(t)值及较为年轻的二阶段模式年龄,揭示出东秦岭稀有金属伟晶岩的源区多样性。伟晶岩的空间分布与俯冲-碰撞密切联系,并且形成时代与区域构造演化之间具有耦合性,体现出构造-深熔-成矿特征,稀有金属伟晶岩可以产出于北秦岭造山带碰撞及伸展的多个阶段。
East Qinling,the eastern segment of the North Qinling orogen,is one of the most important rare-metal metallogenic belts in China,hosting almost 7000 pegmatite dikes that are mainly confined within four pegmatite districts(namely Luanzhuang,Guanpo,Longquanping and Shangnan).In this contribution,we reviewed the spatial distribution,ore occurrence,metallogenic ages and ore-forming conditions of the pegmatites,and further explored the metallogenetic regularity of the rare-metal pegmatites in East Qinling.In terms of spatial distribution,most pegmatites with Li,Be and other rare metal mineralization are distributed along the Luanchuan-Zhuxia and Caichuan faults to north of the Huichizi granitic pluton,and less in the Shangnan area(e.g.,Daweiyuan,Fenghuangzhai,etc.)that is located to the north of the Shangdan sutrure.Such distribution pattern of the rare-metal pegmatites is different from the regional zonation with the Huichizi pluton as the center that were proposed by previous studies.The rare-metal pegmatites predominantly formed from 445Ma to 370Ma.Although there is an age overlap(440~400Ma)between the rare-metal pegmatites and the Paleozoic granites in East Qinling,the geochronological and zircon Hf isotope data indicate that those exposed granitoids are unlikely the parental granites to the majority of the rare-metal pegmatites.Moreover,the zircon Hf isotope data also suggest that the anatexis of the Qinling Complex likely resulted in the rare-metal pegmatites at Guanpo and Shangnan.The lithium pegmatites at Shangnan exhibit higher zirconεHf(t)values and younger t DM2 ages than those at Guanpo,indicating the diversity of the soure regions for the rare-metal pegmatite.The distribution pattern of the rare-metal pegmatites is intimately related to the subduction-collision of the North Qinling orogeny,and the formation ages of the pegmatites also correspond to the tectonic evolution.This implies a tectonic-anatexis-metallogenesis model,and the rare-metal pegmatites were emplaced at multiple stages including the coll
作者
凤永刚
梁婷
岑炬标
王梦玺
谭细娟
高景刚
郭腾龙
王岩
FENG YongGang;LIANG Ting;CEN JuBiao;WANG MengXi;TAN XiJuan;GAO JingGang;GUO TengLong;WANG Yan(School of Earth Science and Resources,Chang an University,Xi'an 710054,China;Xi'an Key Laboratory for Mineralization and Efficient Utilization of Critical Metals,Chang an University,Xi'an 710054,China;Xi'an Center of Mineral Resources Survey,China Geological Survey,Xi'an 710100,China;Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China)
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2024年第9期2703-2728,共26页
Acta Petrologica Sinica
基金
科技部重大研发计划项目(2021YFC2901902、2019YFC0605202)
中央高校基本科研业务费资助项目(300102272504)
国家自然科学基金项目(41902073)联合资助.
关键词
稀有金属伟晶岩
侵位机制
伟晶岩时代
成矿规律
东秦岭
Rare-metal pegmatite
Emplacement mechanism
Pegmatite ages
Metallogenetic regularity
East Qinling
