粤北下庄矿田新生代构造演化及其对铀成矿的影响  

Cenozoic Tectonic Evolution and its Influence on Uranium Ore-forming Processes in the Xiazhuang Ore Field,Northern Guangdong Province

作　　者：王军[1,2] 赖中信[3] 张辉仁 汤世凯 杨坤光[1,2] 

机构地区：[1]中国地质大学(武汉)地球科学学院,湖北武汉430074 [2]中国地质大学(武汉)构造与油气资源教育部重点实验室,湖北武汉430074 [3]广东省核工业地质局二九三大队,广东广州510800

出　　处：《大地构造与成矿学》2011年第3期355-363,共9页Geotectonica et Metallogenia

基　　金：国家自然科学基金项目(40972137);广东省核工业局"南岭贵东花岗岩体构造变形与铀矿成矿关系"项目联合资助

摘　　要：粤北南岭地区是我国重要的花岗岩型铀矿产地,通过野外地质调查与构造变形研究,结合34件石英脉体电子自旋共振(ESR)测年研究,论述了粤北地区下庄矿田的新生代构造演化期次。构造变形研究与ESR年龄测定显示:新生代主要发生了三幕构造变形,第Ⅰ幕(65.5～55.0Ma)为地块的差异升降运动,断裂活动规模大;第Ⅱ幕(40.3～20.0Ma)为间歇性的升降运动,总体为上升趋势;第Ⅲ幕(20.0～2.2Ma)表现为断裂频繁活动,但活动规模小。ESR年龄数据也很好地限定了区内铀矿成矿时代,331、335、336矿床沥青铀矿U-Pb年龄表明成矿最晚发生在60Ma±,与第Ⅰ幕相对应。第Ⅱ幕、第Ⅲ幕使得地块抬升并引发频繁的断裂活动。区内出露的NNE向、NEE向以及近EW向的多组构造在平面上呈"棋盘式"格局,垂向上呈"地堑"式,这种断层组合加剧了花岗岩体上升后的风化、淋滤与剥蚀过程,由此破坏了先存的有利成矿环境。因此,研究新生代构造演化对于探讨新生代以来构造活动对铀矿的控制与影响仍具有重要意义。The Nanling area in northern Guangdong Province is important for its granitic uranium deposits.The characteristics of the structures and ESR ages of the hydrothermal quartz show that the ore field underwent three stages of structural deformation in Cenozoic：（65.5~55.0Ma） differential uplifting of land mass and colossal faults movements;Ⅱ（40.3~20.0Ma） intermittent faulting and uplifting,Ⅲ（20.0~2.2Ma） frequent small scale hydrothermal activities.ESR ages of hydrothermal quartz and U-Pb ages of pitchblender from 331,335,336 uranium deposits demonstrate that the U mineralization took place no later than 60Ma±,which is consistent with the first stage deformation.The second and third stage deformation resulted in uplifting and frequent faulting.The NNE,NEE and the EW-trending structures exhibit chess-board pattern in horizontal and graben-like pattern vertically.The structures aggravated weathering,leaching and denudation processes,and finally destroyed the pre-exist metallogenic environment.Thus,study of the Cenozoic tectonic evolution may contribute to the understanding of the tectonic controls on the uranium ore forming processes.

关 键 词：新生代构造演化 ESR测年 铀矿 粤北下庄矿田 

分 类 号：P613[天文地球—矿床学]