摘要
赛角铜金矿是西藏多龙超大型铜金矿集区的组成矿床之一,目前对其成岩成矿时代、矿床成因等方面的认识程度还很低,制约了对多龙矿集区成矿潜力的全面认识。对赛角闪长岩进行LA-ICP-MS锆石U-Th-Pb同位素、全岩主量和微量元素、锆石Hf同位素测试。测得闪长岩中锆石U-Pb年龄为120.5±1.2Ma,该年龄被解释为岩浆结晶年龄。全岩主量和微量元素分析显示,闪长岩为中钾—高钾钙碱性岩石,富集轻稀土元素和大离子亲石元素,亏损重稀土元素和高场强元素,具有活动大陆边缘弧岩浆岩的特征。锆石Hf同位素分析结果表明,锆石εHf(t)值为+5.4^+12.1,平均值为+9.0,二阶段Hf模式年龄为373~743Ma,平均值为545Ma,表现出明显的幔源特征。赛角铜金矿的形成受控于班公湖—怒江洋陆俯冲体系,成岩成矿岩浆是板片流体交代的地幔楔部分熔融形成的基性母岩浆与新生下地壳部分熔融形成的酸性岩浆混合的产物。
The Saijiao Cu-Au deposit is a component part of the Duolong Cu-Au metallogenic concentration area; nevertheless, the study of its metallogenic epoch and genesis remains very insufficient. This paper reports zircon U-Th-Pb isotope and Hf-isotope as well as whole-rock major and trace element data from diorite in Saijiao. Zircon LA-ICP-MS dating of the diorite yields a weighted mean age of 120.5±1.2Ma, which can be regarded as the age of magmatic crystallization. Whole-rock major and trace ele- ment data show that the diorite belongs to high （mediate）-K calc-alkaline series characterized by enrichment of light rare earth elements and large ion lithophile elements, indicating that the diorite formed in a continental arc setting. The positive e .f（t） values of zircons are ＋5.4-＋ 12.1, and second stage Hf mode ages tDM2 are 373-743Ma. The formation of Saijiao Cu-Au deposit was controlled by the Bangong Co-Nujiang River oceanic subduction system, and its rock-forming and ore-forming magma might have resulted from the mixing between the juvenile lower crust-derived melts and mantle-derived mafic melts.
出处
《地质通报》
CAS
CSCD
北大核心
2015年第5期908-918,共11页
Geological Bulletin of China
基金
国家自然科学基金项目(批准号:41272240
41072166
41273047)
中国地质调查局项目(编号:1212011121248
1212011221093
12120113036700)
关键词
赛角
多龙矿集区
铜金矿
锆石U-PB定年
Saijiao
Duolong metallogenic concentration area
Cu-Au deposit
zircon U-Pb dating
