摘要
粤西高枨矿床是云开地区最近几年新发现的大型铅锌银多金属矿床,矿体赋存在黑云母花岗岩的构造断裂带中,空间上与黑云母花岗岩密切相关。这种现象与国内多数热液脉状铅锌矿体产在地层或岩体与地层的接触带上明显不同,花岗岩与矿床之间的时间和成因关系尚不明确。本文选择锆石SHRIMP U-Pb测年获得花岗质糜棱岩、黑云母花岗岩和英云闪长岩的206Pb/238 U年龄加权平均值分别为451.5±2.8Ma(MSWD=0.27,n=7)、463.3±3.3Ma(MSWD=1.4,n=10)和450.0±4.5Ma(MSWD=3.4,n=12),揭示其岩体的准确结晶年龄为450~463Ma,为中—晚奥陶世,属于加里东期岩浆活动的产物,并保留有中—新元古代的基底信息。这一年龄结果比以往黑云母花岗岩的结晶年龄(429Ma和438Ma,早—中志留世)要早20~30Ma。黑云母花岗岩体作为含矿围岩,其形成时代明显早于成矿期,该矿床形成时代极有可能是晚白垩世之后。据区域地质资料和最新研究成果综合研究,认为高枨矿区存在一期450~463Ma的加里东期构造岩浆热事件,是于板内俯冲模式下陆内造山作用导致中—新元古代地壳物质发生部分熔融的产物。
The Gaocheng deposit is a newly-discovered large-sized silver-lead-zinc polymetallic deposit in the Yunkai area of western Guangdong.Orebodies occur mainly in structural fractures of biotite granitic rock and show close spatial relation to biotite granitic rock.This phenomenon is significantly different from majority of China’s hydrothermal vein lead-zinc deposits in that the latter has orebodis occur mainly in strata or contact zone between rockbodies and strata.The timing and genetic relationship between granite and ore deposits is unclear at present.This study carried out high-precision SHRIMP U-Pb zircon analyses for the zircons from granitic mylonite,biotite granite and tonalite in the Gaocheng deposit.Three zircon ^206U/^238Pb concordant ages of 451.5±2.8 Ma (MSWD=0.27,n=7),463.3±3.3 Ma (MSWD=1.4,n= 10) and 450.0±4.5 Ma (MSWD=3.4,n=12) were obtained for granitic mylonite,biotite granite and tonalite,respectively,revealing that the rocks crystallized at 450~463Ma (Middle-late Ordovician)and should be the products of the Caledonian magmatism and also carry some Meso-Neoproterozic basement information.These ages are 20~30 Ma earlier than the crystallization age of biotite granites (429 Ma and 438 Ma,early Silurian).Biotite granitic rock,as the ore-bearing country rocks,formed earlier than oreforming period of the Gaocheng polymatallic deposit,indicating that the deposit formed likely after Late Cretaceous.Based on the regional geological data and the latest research results,it can be concluded that one thermal tectonic magmatic event occurred in the Gaocheng mining area at Caledonian period (450~463 Ma),which was the product of partial melting of the Meso-Neoproterozoic crustal material caused by Early Paleozoic intracontinental Wuyi-Yunkai orogeny in the background of intracontinental subduction.
作者
于小鸽
李宝龙
郑伟
刘鹏
侯淋
YU Xiaoge;LI Baolong;ZHENG Wei;LIU Peng;HOU Lin(Department of Resources and Civil Engineering,Shandong University of Science and Technology ,Taian,Shandong,271019;MLR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing ,100037;School of the Earth Sciences and Resources ,China University of Geosciences,Beijing,100083)
出处
《地质学报》
EI
CAS
CSCD
北大核心
2018年第3期531-544,共14页
Acta Geologica Sinica
基金
国家自然科学基金项目(编号41572244)
山东省自然科学基金项目(编号ZR2015DM013)
教育部高等学校博士学科点专项科研基金项目(编号20133718110004)联合资助成果
