大地构造与成矿学2025，Vol.49Issue(1) ：70-84,中插6-中插10.DOI:10.16539/j.ddgzyckx.2024.01.133

桂北苗儿山铀矿田铀源分析:来自周缘红盆碎屑锆石的制约

Uranium Source of the Miao'ershan Uranium Orefield,Northern Guangxi:Constraints from Detrital Zircons in the Faulted Red Basin

谭双 刘晓东 雷勇亮 陈琪 万建军 吴昆明 欧阳平宁 黄宏业
大地构造与成矿学2025，Vol.49Issue(1) ：70-84,中插6-中插10.DOI:10.16539/j.ddgzyckx.2024.01.133
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桂北苗儿山铀矿田铀源分析:来自周缘红盆碎屑锆石的制约

Uranium Source of the Miao'ershan Uranium Orefield,Northern Guangxi:Constraints from Detrital Zircons in the Faulted Red Basin

谭双 1刘晓东 2雷勇亮 3陈琪 3万建军 2吴昆明 3欧阳平宁 3黄宏业3
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作者信息

  • 1. 东华理工大学 核资源与环境国家重点实验室,江西 南昌 330013;核工业二三〇研究所,湖南 长沙 410007;湖南省伴生放射性矿产资源评价与综合利用工程技术研究中心,湖南 长沙 410007
  • 2. 东华理工大学 核资源与环境国家重点实验室,江西 南昌 330013
  • 3. 核工业二三〇研究所,湖南 长沙 410007;湖南省伴生放射性矿产资源评价与综合利用工程技术研究中心,湖南 长沙 410007
  • 折叠

摘要

花岗岩型热液铀矿床铀源的认识目前存在一定分歧,部分观点认为铀矿床周缘红盆可能提供成矿物质来源.苗儿山铀矿田是华南地区典型的花岗岩型铀矿田之一,但关于周缘红盆与铀矿床之间的关系尚未开展过系统研究.本次研究选取苗儿山地区红盆内的碎屑岩为研究对象,对其开展岩相学、碎屑锆石U-Pb年代学和地球化学研究,旨在限定碎屑岩的形成时代上限和物质来源,进而探讨区内铀矿床的铀源问题.锆石CL图像和稀土元素分布特征显示,研究区内碎屑岩的锆石为岩浆锆石,LA-ICP-MS锆石U-Pb年龄为 416～2485 Ma,主要峰值集中在 721～839 Ma和 416～436 Ma,与苗儿山铀矿田晋宁期和加里东期构造-岩浆热事件时间一致.锆石元素面扫描图像特征显示,其具有较强的流体交代痕迹,U元素存在明显的活化迁移行为,记录了一定程度的蚀变改造或矿物溶解沉淀过程.通过系统收集苗儿山铀矿田及其周边侵入岩的年代学数据并进行对比分析,认为 721～839 Ma的碎屑锆石可能主要来自苗儿山地区花岗岩和湖南城步地区新元古代花岗岩;而 416～436 Ma的锆石主要来自越城岭-苗儿山加里东期复式花岗岩基.结合前人研究,认为苗儿山铀矿田中的部分铀源可能来自区内新资断陷红盆碎屑岩,富含CO2 等矿化剂的幔源流体沿着深大断裂上升与循环的地下水结合形成热液,与富铀花岗岩、红盆碎屑岩等相互作用,进而形成富铀的成矿流体.

Abstract

The source of granite-related hydrothermal uranium deposits is still controversial,and red basins around the uranium deposits are believed to be the source of ore-forming materials.The Miao'ershan is a typical granite-related uranium orefield in South China,however,the relationship between the red basin and the uranium deposit remains unclear.To determine the formation age and material source of classic rocks in the red basin and discuss the source of the uranium deposit,the petrography,detrital zircon U-Pb dating,and trace element characteristics of the clastic rocks from the red basin in the Miao'ershan area were analyzed.The CL images and rare earth element characteristics indicated that the zircon grains are magmatic origin.LA-ICP-MS U-Pb dating of the detrital zircons yielded an age range of 416-2485 Ma,with the main peaks of 721-839 Ma and 416-436 Ma,which are consistent with the timing of the Jinningian Period and Caledonian tectonic-magmatic events in the Miao'ershan uranium ore field.EPMA element maps of the altered zircon grain from the clastic rock samples indicated that the zircon grains show strong fluid metasomatism,and the obvious activation and migration of uranium recorded the alteration and mineral dissolution-precipitation processes.Considering of the chronological data of granites in the surrounding areas,we suggest that the detrital zircons of 721-839 Ma mainly derived from the Neoproterozoic Jingningian Period granites in the Miao'ershan area and the Neoproterozoic granites in the Chengbu area of Hunan province.The zircons of 416-436 Ma mainly originated from the Yuechengling-Miao'ershan Galedonian granite batholith.Based on the previous data,it is believed that part of the uranium in the Miao'ershan uranium ore-field originated from the clastic rocks in the Xinzi faulted red basin.The CO2-rich mantle derived fluids rose along the deep faults,and mixed with the circulating groundwater to form hydrothermal fluids,which interacted with U-rich granites and clastic rocks,released the uranium in the rocks,and formed uranium-rich ore-forming fluids.

关键词

新资断陷红盆/苗儿山铀矿田/碎屑锆石/年代学/稀土元素/铀源

Key words

Xinzi faulted red basin/Miao'ershan uranium field/detrital zircon/chronology/rare earth elements/uranium source

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出版年

2025
大地构造与成矿学
中国科学院广州地球化学研究所

大地构造与成矿学

CSCD北大核心
影响因子：1.45
ISSN：1001-1552
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