第2期
第31卷 2017年4月
现代地质 GEOSCIENCE
内蒙古核桃坝地区流纹斑岩的地球化学
特征及与铀富集的关系
蒋孝君，刻鹏兵，薛伟，邢亚杰，刘小刚，颜小波
（核工业二O八大队，内蒙古包头014000）
Vol.31Na.2 Apr.2017
摘要：内蒙古核桃坝地区流纹斑岩体与该区铀成矿有着密切关系，为了寻求找矿突破，通过地球化学和岩浆与构造演化等方法，着重讨论流纹斑岩和构造与铀富集的关系。该流纹斑岩体位于多伦火山盆地榛子山破火山口南部，岩石富硅(w(Si0,）= 70.15%~78.58%)，富碱(w(Na,0+K,0)=7.49%~10.82%)，属钾质（te(K,0)=5.28%~9.30%); A/CNK的值在0.84~1.28之间，在火山岩TAS分类图解中全部样品均落人亚碱性流纹岩范围内，属于亚碱性系列流纹
岩类；稀土总量高（ZREE=254.47×10
499.99 ×10 -6
度强；亲石元素Rb、Th相对富集，特别是U含量（6.66x
，其中轻稀土元素富集，重稀土元素亏损，轻重稀土分馏程
966.00×10-）异常富集，部分数据极高，而Sr和Eu
明显亏损。岩石岩浆物质来源于下地壳的部分熔融，侵位于后碰撞构造环境，属于A2型花岗岩类型。伸展构造背景下的富轴流纹斑岩侵位、后期促进铀运移富集的成矿构造及富铀热液随构造上移并进一步萃取等多种事件共同作用，最终促成了核桃坝铀矿床的形成。
关键词：核桃坝；流纹斑岩；地球化学；构造；轴
中图分类号：P588
文献标志码：A
文章编号：10008527(2017)02022509
GeochemicalCharacteristicsofRhyolitePorphyryandRelationship BetweentheRockandEnrichedUraniuminHetaoba,InnerMongolia
JIANG Xiaojun，YAN Pengbing，XUE Wei,XING Yajie,LIU Xiaogang，YAN Xiaobo
(The Nuclear Industry Brigade 208, Baotou, Iner Mongolia 014000, China)
Abstract: Rhyolite porphyry in Hetaoba, Inner Mongolia, is closely associated with uranium mineralization of the area. In order to strengthen the theory research and seek the prospecting breakthrough, this article focuses on the relationship between uranium mineralization and rhyolite porphyry, structure by the methods of geochem-istry and magma and tectonic evolution. The pluton is located in the southem of Zhenzishan caldera in Duolun volcano basin. The rock has high Si0, content (70. 15% 78. 58% ), high K,0 (5. 28% 9. 30% ) and are enriched in alkali contents ( Na, 0 + K,0 =7. 49% 10. 82% ). It belongs to the alkaline rhyolite as shown in the plot of TAS. Rhyolite porphyry in Hetaoba shows high REE contents and is relatively enriched in LREE, Rb, Th, with evidently negative Eu and Sr anomalies. Especially, U element content is extremely high (6. 66 ×10- 966. 00 × 10-6). The magma came from partial melting of the lower crust materials, and the pluton, belonging to A2 subtype granite, was likely emplaced in the extensional post-collision setting. Eventually, these factors including emplacement of rhyolite porphyry, the ore-forming structure in the late stage, the emplacement and extraction of hydrothermal with rich uranium, have led to the formation of the Hetaoba uranium deposit
收稿日期：2016-03-01；改回日期：2016-09-30；责任编辑：威开静。
基金项目：中国地质调查局项目（DD2016013624)；中国核工业地质局舶矿地质科研项目（201604-4)；中国国防科工局核能开
发项目（2013-2016)；核工业二O八大队科研项目(201601)。
作者简介：蒋举君，男，碳士，助理工程师，1987年出生，地质矿产勘查专业，主要从事构造及轴矿地质研究。
Email; 523990392@ q9, com。
通信作者：刻鹏兵，男，工程师，1986年出生，地质矿产助查专业，主要从事构造及铀矿地质研究。
Email; 649929349@ qq. com。