摘要
西藏拿若铜(金)矿床是多龙矿集区重要矿床之一,矿体边部存在一岩浆作用的隐爆角砾岩筒。隐爆角砾岩中存在两种岩浆岩:一种是早期花岗闪长斑岩;一种是引起隐爆作用的岩浆热液形成的胶结物。此次工作以两种岩浆岩为对象,研究其锆石的Hf同位素特征。花岗闪长斑岩的锆石^(176)Hf/^(177)Hf值介于0.282789~0.282905之间,176Lu/177Hf值介于0.000406~0.001042之间,ε_(Hf)^(t)值介于3.17~7.24之间,二阶模式年龄(tDM2)为713~978Ma。胶结物锆石的^(176)Hf/^(177)Hf介于0.282777~0.282858之间,^(176)Lu/^(177)Hf值介于0.000441~0.001572之间,ε_(Hf)^(t)值为2.69~5.54,二阶模式年龄(tDM2)为823~1005M。两期岩体的ε_(Hf)^(t)值都是较小的正值,都具有年轻二阶模式年龄。拿若隐爆角砾岩中锆石Hf同位素特征显示,两期岩浆均具有壳幔混源的特征。拿若矿床的形成受控于特提斯洋壳俯冲作用。
The Naruo copper （gold） deposit in Tibet is one of the most important deposits in the Duolong ore-concentration area. There is a cryptoexplosive breccia associated with magmatism at the edge of the orebody. Two types of magmatic rocks are present in the cryptoexplosive breccia： one is early granite diorite porphyry, and the other is cements formed by magmatic hydrothermal causing cryptoexplosive. This work studied the zircon Hf isotopic characteristics of the two types of magmatic rocks. The results show that zircon 176Hf/177Hf values of granite diorite porphyry are 0.282789~0.282905, 176Lu/177Hf values of 0.000406~0.001042, εHf（t） values of 3.17~7.24 and two-stage model age （tDM2） of 713~978Ma. Zircon 176Hf/177Hf values of cements are 0.282777~0.282858, 176Lu/177Hf values of 0.000441~0.001572, εHf（t） values of 2.69~5.54, two-stage model ages （tDM2） of 823~1005M. εHf（t） values of two magmas both are small positive values and young the two-stage model ages. Zircon Hf isotope characteristics in the cryptoexplosive breccia show that two-period magmas are characterized by crust-mantle mixing. The formation of the Naruo deposit was controlled by the Tethyan oceanic subduction.
出处
《地质与勘探》
CAS
CSCD
北大核心
2017年第2期207-216,共10页
Geology and Exploration
基金
国家自然科学青年基金(41402178)
中国地质科学院基本科研业务费(YYWF201608)
国土资源部公益性行业科研专项项目(201511017
201511022-02)
青藏专项地质调查项目(12120114050401)
中国地质调查局项目(DD20160026)
中铝资源西藏金龙矿业股份有限公司项目(XZJL-2013-JS03)联合资助
关键词
锆石HF同位素
隐爆角砾岩
岩浆岩
拿若
多龙矿集区
西藏
zircon Hf isotope, cryptoexplosive breccia, magmatic rock, Naruo, Duolong ore - concentration area, Tibet
作者简介
高轲（1987年-），男，博士研究生，矿物学、岩石学、矿床学专业，研究方向：矿床学与成矿规律。E-mail：gaokely@163．com。
