摘要
朱诺斑岩铜钼金矿位于冈底斯成矿带南缘,是近年来在冈底斯斑岩铜矿带最西端新发现的另一大型斑岩型铜-钼-金矿床,但一直以来对该矿区花岗岩年代学及成因分析缺乏系统的研究。本文选择矿区内主要岩浆岩体开展LA-ICP-MS锆石U-Pb定年,Hf同位素研究。获得黑云母花岗闪长岩锆石U-Pb年龄为14.14±0.32Ma,76 Hf/177 Hf介于0.282484~0.282750,εHf(t)介于-9.87^-0.49,二阶段模式年龄TDMC介于1.13~1.73Ga、似斑状二长花岗岩锆石U-Pb年龄为14.05±0.31Ma,176 Hf/177 Hf介于0.282633~0.282769,εHf(t)介于-4.61~0.21,二阶段模式年龄TDMC介于1.08~1.39Ga之间;角闪闪长玢岩锆石U-Pb年龄为14.10±0.29Ma,除4.1号为继承锆石外,其余测点176 Hf/177 Hf介于0.282607~0.282761,εHf(t)介于-5.53^-0.07,二阶段模式年龄TDMC介于1.10~1.45Ga之间。年代学与Hf同位素结果表明,朱诺斑岩铜矿与斑岩铜矿带中段和东段成岩成矿时代一致,集中在15~13Ma之间,指示了冈底斯在中新世的构造岩浆活动事件。花岗岩Hf同位素组成明显与中-东段斑岩矿床不同,具有富集Hf同位素特征以及古老二阶段模式年龄(1.08~1.73Ga)等特点,反映出朱诺矿区中新世岩浆岩源区与中-东段中新世斑岩矿床明显不同,可能指示古老拉萨地体的印迹。
Zircon LA ICP-MS U-Pb dating and Hf isotopic compositions of intrusions from Zhunuo porphyry copper-gold-molybdenum and its geological significance. But the chronology and petrogenesis of intrusions are still unclear. According to research of Zircon U-Pb dating and Hf isotope study, we obtained the age of biotite granodiorite is 14.14＋0.32Ma,176 H{/177 Hf, eHf （t）, and two-stage age range from 0. 282484 to 0. 282750, - 9.87 - 0.49 and 1.13- 1.73Ga respectively; The age of monzonitic granite is 14.05 - 0.31Ma, 176 Hf/177 Hf is 0. 282633 - 0. 282769, CH （t） is - 4.61 - 0.21, and two-stage age is 1.08 1.39Ga; The age of hornblende diorite porphyry is 14.10!0.29Ma,176 Hf/177 Hf is 0. 282607-0. 282761, m（t） is --5.53-0.07 with two-stage age between 1.10-1.45. The studies indicated that the ages of intrusions are similar to porphyry copper-molybdenum deposits at east of Gangdise metallogenic belt showing the similar, but Hf isotopic composition and older two stage model age （1.1 - 1.3Ga） are significantly different which show the more crustal contamination compared with Miocene porphyry coppermolybdenum deposits.
出处
《地质学报》
EI
CAS
CSCD
北大核心
2015年第1期99-108,共10页
Acta Geologica Sinica
基金
西藏大型矿床成矿专属性研究(编号:1212011221073)
西藏铜铅锌国家级接替基地综合研究(编号:1212011121239)
青藏高原南部矿床勘查模型与定位预测技术(编号2011CB403105)项目联合资助的成果
