摘要
粤北长江铀矿田是中国南方最重要和最具代表性的花岗岩型铀矿田之一。前人关于长江铀矿田的研究工作主要涉及铀矿成因、成岩成矿时代和铀矿化机制等方面,关于控矿构造研究也集中在矿床形成过程方面(如导矿、运矿和储矿构造),对成矿后矿床的剥露历史和保存研究甚少。本文通过磷灰石裂变径迹测试,恢复了长江铀矿田热演化历史,结果显示晚白垩世末以来表现为单向隆升剥露降温过程,在约63~55 Ma和44~34 Ma存在两次快速隆升过程,约34~5 Ma冷却速率较慢,为构造平静期,5 Ma以来又发生了快速隆升。自75 Ma至今长江铀矿田的隆升剥蚀量为3 km左右。矿田内被NEE向棉花坑断裂和NWW向油洞断裂分割的书楼丘、棉花坑和长排三个矿区隆升剥蚀量差异非常微小,说明棉花坑断裂两侧和油洞断裂两侧在新生代时期没有明显的差异升降,也进一步佐证了棉花坑断裂和油洞断裂的活动性不大。结合控矿构造的发育特点、3.2~5.6 km的成矿深度以及相关的成矿温压条件,表明长江铀矿田深部资源保存良好,深部具有很大的找矿潜力。
The Changjiang uranium ore field is one of the most important granite-type uranium ore fields in Southern China.Previous studies on the Changjiang uranium ore field have mainly involved uranium genesis,metallogenic epochs,and uranium mineralization mechanisms.Research on the ore-controlling structure has also focused on mineralization processes(e.g.ore-conducting,ore-transporting,ore-bearing structures),and less focused on the denudation and preservation of ore deposits.In this paper,through an apatite fission track test,the authors restored the thermal evolution history of the Changjiang uranium ore field.The results showed that unidirectional uplift,denudation,and cooling have been manifested since the end of the Late Cretaceous.There were two rapid uplift processes at about 63-55 Ma and 44-34 Ma,and the cooling rate was slower at about 34-5 Ma,which was a tectonic calm period.A rapid uplift occurred after 5 Ma before present.Since 75 Ma,the uplift and denudation in this area have been amounted to about 3 km.There are very small differences in thermal history among the three uranium deposits,i.e.,the Shulouqiu,Mianhuakeng,and Changpai deposits,which are divided by the NEE-trending Mianhuakeng fault and the NWW-trending Youdong fault,indicating that there has been no obvious difference in denudation between the two sides of the Mianhuakeng fault and the two sides of the Youdong fault in the Cenozoic since 65 Ma.Hence,it can be inferred that the Mianhuakeng and Youdong faults are not active.Combined with the development characteristics of the ore-controlling structures,the metallogenic depth of about 3.2-5.6 km,and the related metallogenic temperature and pressure conditions,it can be concluded that the deep resources of the Changjiang uranium ore field are well preserved and have great prospecting potential.
作者
陈柏林
高允
王永
刘向冲
祁家明
CHEN Bailin;GAO Yun;WANG Yong;LIU Xiangchong;QI Jiaming(Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081,China;Beijing General Research Institute of Mining&Metallurgy Technology Group,Beijing 100160,China;Research Institute No.290,China National Nuclear Corporation,Shaoguan 512029,Guangdong,China)
出处
《大地构造与成矿学》
EI
CAS
CSCD
北大核心
2024年第5期911-927,共17页
Geotectonica et Metallogenia
基金
国家重点研发计划项目(2017YFC0602602,2016YFC0600207)
院所长基金项目(JYYWF20180602)联合资助。
关键词
裂变径迹
低温热年代学
剥露
矿床保存
长江铀矿田
粤北
apatite fission track
low-temperature thermochronology
denudation
ore deposit preservation
Changjiang uranium ore field
North Guangdong
