| 粤北青嶂山岩体江头矿区铀矿微区矿物学、年代学特征及其成矿动力背景制约 |
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| 引用本文： | 赖静,祁家明,陈军军,李钟枢,曹豪杰.粤北青嶂山岩体江头矿区铀矿微区矿物学、年代学特征及其成矿动力背景制约[J].地质学报,2020,94(4):1128-1142. |
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| 作者姓名： | 赖静 祁家明 陈军军 李钟枢 曹豪杰 |
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| 作者单位： | 核工业二九〇研究所，广东韶关，512026 |
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| 基金项目： | 本文为中国地质调查局“全国重要矿集区找矿预测”项目（编号：DD2016005209）；中核集团集中研发项目（编号：地LTD1602）；中国核工业地质局科研项目（编号：201639、201836）；广东省诸广矿集区铀矿资源调查评价与勘查（编号：201926）资助的成果。 |
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| 摘 要： | 粤北诸广和贵东是华南最重要的两个花岗型铀矿密集区,青嶂山(龙源坝)岩体位于两者之间,是华南花岗岩型铀矿研究薄弱地区。江头铀矿区地处青嶂山岩体北部与南雄断陷盆地的结合部位,该矿区的铀成矿年代学研究几为空白。本文通过电子探针方法研究了青嶂山岩体、及与该岩体密切相关的江头矿区中的铀矿物微区矿物学特征,获得岩浆成因的晶质铀矿与热液成因的沥青铀矿的U-Th-Pb化学年龄,探讨了华南铀成矿作用动力学背景及成矿地质体。研究表明:青嶂山岩体粗粒斑状黑云母花岗岩和中粒斑状黑云母花岗岩中的铀矿物主要有晶质铀矿、铀石,部分晶质铀矿存在明显铀释放的特征,其晶质铀矿化学年龄分别为246.8±8.8Ma、161.5±8.0Ma,与前人获得的锆石U-Pb年龄结果在误差范围内一致,分别代表了区内印支期与燕山期花岗岩体的成岩年龄,表明在南雄断陷盆地形成之前,青嶂山岩体与诸广岩体可能为一有机整体,有着相同的成岩、成矿环境。江头矿区矿石中铀矿物主要为沥青铀矿,伴有少量钛铀矿、铀石等,沥青铀矿化学年龄分别为121.3±9.8Ma、98.8±8.0Ma、73.2±8.8Ma,分别代表区内3期铀成矿作用的时代,结合华南中生代以来构造运动特征,认为区内铀成矿作用是受中-新生代盆地边缘深大断陷活动、产铀花岗岩体分布的双要素成矿动力学背景制约,青嶂山岩体应与诸广、贵东岩体具有相似的找矿前景。
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| 关 键 词： | 青嶂山岩体 江头矿区 铀矿物特征 化学年龄 成矿动力背景 |
| 收稿时间： | 2019/1/4 0:00:00 |
| 修稿时间： | 2019/4/17 0:00:00 |
Uranium micromineralogy and geochronology of the Jiangtou Uranium Ore Field in the Qingzhangshan granite pluton, north Guangdong: constraints on the genetic relationship with metallogenic dynamic background |
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| LAI Jing,QI Jiaming,CHEN Junjun,LI Zhongshu,CAO Haojie.Uranium micromineralogy and geochronology of the Jiangtou Uranium Ore Field in the Qingzhangshan granite pluton, north Guangdong: constraints on the genetic relationship with metallogenic dynamic background[J].Acta Geologica Sinica,2020,94(4):1128-1142. |
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| Authors: | LAI Jing QI Jiaming CHEN Junjun LI Zhongshu CAO Haojie |
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| Institution: | Research Institute No. 290, CNNC, Shaoguan, Guangdong, 512026 |
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| Abstract: | Qingzhangshan (Longyuanba) pluton, located between the Zhuguang and the Guidong granitic complexes that are two of the most important granite type uranium concentration areas in South China, is a poorly investigated area in the study of granite type uranium deposits. Jiangtou uranium mining area is located in overlap region of the northern part of the Qingzhangshan pluton and the Nanxiong fault basin. Till date, the chronology of the uranium deposits remains unknown. The micromineralogical characteristics of uranium in this area have been studied by means of electron microprobe. At the same time, the U Th Pb chemical ages of magmatic crystalline uraninite and hydrothermal pitchblende have been calculated, and the dynamic background of uranium mineralization and ore formation has been discussed. Results show that the uranium minerals in the coarse grained porphyritic biotite granite and medium grained porphyritic biotite granite are mainly uraninite and coffinite and some uraninite show obvious characteristics of uranium release. The chemical ages of uraninite are 246. 8±8. 8 Ma and 161. 5±8. 0 Ma which are consistent with the range of previous zircon U Pb ages, representing the diagenetic ages of the Indosinian and the Yanshanian granites respectively. It shows that before the formation of Nanxiong fault basin, the Qingzhangshan pluton and the Zhuguang pluton were an organic whole with the same diagenetic and metallogenic environment. The uranium minerals in the ore of the Jiangtou mining area are mainly disseminated pitchblende accompanied by a small amount of brannerite, coffinite, etc. The chemical ages of pitchblende are 121. 3±9. 8 Ma, 98. 8±8. 0 Ma and 73. 2±8. 8 Ma, representing ages of three stages of uranium metallogenesis in this area. Combined with the six tectonic extensional movements since the Mesozoic, it had been considered that uranium mineralization in this area is controlled by dual factors: metallogenic dynamic background of deep fault depression activity in the margin of Mesozoic Cenozoic basins, and the distribution of uranium producing granite bodies. The Qingzhangshan pluton should have similar prospecting prospects as the Zhuguang and the Guidong plutons. |
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| Keywords: | Qingzhangshan pluton Jiangtou mining area Characteristics of uranium minerals Chemical ages Geodynamic background of mineralization |
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