| 东秦岭丹凤地区伟晶岩型铀矿矿化特征与成矿模式 |
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| 引用本文： | 王江波,侯晓华,李万华,张良,赵友东,陈宏斌,李卫红.东秦岭丹凤地区伟晶岩型铀矿矿化特征与成矿模式[J].地球科学,2020,45(1):61-71. |
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| 作者姓名： | 王江波 侯晓华 李万华 张良 赵友东 陈宏斌 李卫红 |
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| 作者单位： | 1.西北大学地质学系, 陕西西安 710069 |
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| 基金项目： | 国防预研项目3210402中国地质调查局地质矿产调查项目DD2016013623陕西省青年科技新星专项2017KJXX-94中国核工业地质局铀矿地质项目201621中国核工业地质局铀矿地质项目201572 |
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| 摘 要： | 伟晶岩型铀矿是北秦岭成矿带东段重要的铀矿类型，本文介绍了该类型铀矿的矿体特征、矿石特征、副矿物特征和年代学特征.铀矿体产于淡色含榴花岗岩体内外接触带伟晶岩脉中，围绕花岗岩体产出，形态复杂，随伟晶岩脉的形态而变化，呈似脉状、透镜状和不规则状，晶质铀矿为最主要的工业矿物.通过LA-ICP-MS锆石U-Pb定年获得含铀伟晶岩年龄为404.3±1.4 Ma，略晚于淡色含榴花岗岩体年龄，矿岩时差小，显示了岩浆成矿的特征.综合分析表明早泥盆世丹凤地区进入后碰撞构造环境，秦岭岩群发生部分熔融形成富铝含榴花岗质岩浆，随着岩浆结晶分异演化的不断进行，铀元素以U4+形式与O2-结合形成晶质铀矿，在岩体内外接触带黑云母富集部位沉淀成矿.三叠纪后接受长期隆升剥蚀，侵入岩呈岩株出露地表，围绕岩株外带产出的含铀伟晶岩脉，表现为光石沟式铀矿床.随着隆升剥蚀作用的进一步加剧，侵入岩顶部相遭受剥蚀之后以岩基出露地表，在岩体的内接触带不规则形态的含铀伟晶岩出露地表，表现为陈家庄式铀矿床.依据成矿模式，预测伟晶岩型铀矿成矿远景区2片，分别为大毛沟地区和纸房沟地区.
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| 关 键 词： | 伟晶岩型铀矿 矿化特征 成矿模式 丹凤地区 东秦岭 岩石学 |
| 收稿时间： | 2018-07-28 |
Metallogenic Characteristics and Metallogenic Model of the Pegmatite Type Uranium Deposit in Danfeng Area,Eastern Qinling Mountains |
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| Abstract: | Pegmatite-type uranium deposit is the most important uranium deposit in the eastern part of northern Qinling metallogenic belt. This paper presents a study of the metallogenic and geochronological characteristics of the ore body,ores,and accessory minerals. Uranium ore-body occurs in pegmatite dykes around the garnet-bearing leucogranite and uraninite is the major industry mineral. The accessory minerals of uranium bearing pegmatite are similar to those of garnet-bearing granitic rocks,but different from gneissic granitic rocks. The results of LA-ICP-MS zircon U-Pb dating of uranium bearing pegmatite is 404.3±1.4 Ma,Early-Devonian. Comprehensive data suggest that the Danfeng garnet-bearing granitic rocks were derived from partial melting of Qinling Group in the post-collision setting during Early-Devonian. The residue magmas were enriched in Th-U and other moderate-incompatible elements but low content of volatile component which have relative short migration. The pegmatite-type uranium was formed near the internal and external contact zone of the pluton. The pluton was emplaced as the stock in the surface which experienced the long time uplift and erosion after the Triassic. Then the uranium-bearing pegmatite dykes were distributed around the stock,which resulted in the Guangshigou uranium deposit. The intrusions at the top were emplaced as the batholiths in the surface after the anabatic uplift and erosion. Thus,the uranium-bearing pegmatites were developed in the internal contact zone,for example,Chenjiazhuang uranium deposit. Based on the metallogenic model,Damaogou and Zhifanggou areas are determined as two areas of metallogenic prospect of pegmatite-type uranium deposit. |
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