摘要
玉龙斑岩铜矿带位于特提斯-喜马拉雅构造域东缘三江构造带的中部,是研究碰撞后喜山期富碱斑岩成岩成矿作用响应的最佳地区。本文选择玉龙和多霞松多两个矿床,分析了两地含矿斑岩的成岩成矿年龄及岩石地球化学特征,并结合Sr-Nd-Pb、S-H-O同位素进一步探讨了与冈底斯含矿斑岩岩浆源区组成、构造控矿模式及深部动力学机制上的差异。赋矿岩体均具有富碱、高K、高Al等钾质碱性岩系列特征,玉龙早期为石英二长斑岩,晚期为花岗闪长斑岩和石英二长斑岩,多霞松多早期为二长花岗斑岩和花岗闪长斑岩,晚期为碱长花岗斑岩,两者明显富集轻稀土和大离子亲石元素Rb、Th、U、Pb,相对亏损高场强元素Nb、Ta、Yb,无明显Eu、Ce负异常。略高于原始地幔现代值的^(87)Sr/^(86)Sr值、较低的ε_(Nd)(t)、相对均一的^(206)Pb/^(204)Pb值,指示斑岩岩浆可能源自接近于EMⅡ型富集地幔交代成因的石榴石角闪岩和/或角闪榴辉岩的部分熔融,并发生低程度结晶分异,在上升侵位途中受到地壳物质的混染,其形成于古近纪中始新世喜马拉雅期的37~41 Ma左右,可能受控于印度板块与欧亚板块碰撞诱发的红河-哀牢山走滑断裂系统,尤其是妥坝-芒康断裂(TBF)左行走滑产生的局部俯冲作用。
The Yulong porphyry copper belt, located in the middle of the Sanjiang tectonic zone of the eastern Tethys-Himalayan tectonic domain, is an ideal area to study the petrogenesis and mineralization of the Himalayan alkali-rich porphyries. This paper takes the Yulong and Duoxiasongduo as the study areas, presenting detailed dating on the porphyries and associated Cu-Mo mineralization as well as their geological and geochemical characteristics. Combined with Sr-Nd-Pb and S-H-O isotopic analysis, we discussed the difference of ore-bearing magma source, tectonic controls on mineralization, and dynamic mechanism between the Yulong and Gangdese ore-bearing porphyries. The results show that the ore-bearing porphyries which are of potassic alkali-granite and characterized by rich alkali, high potassium and high aluminum. In the Yulong area, the rocks mainly consist of quartz monzonite porphyry in the early stage, the granodiorite and quartz monzonite porphyry in the late stage. While in the Duoxiasongduo area, the rocks mainly consist of monzogranite and granodiorite porphyries, and less K-feldspar granite porphyry. Both of them are rich in light rare earth elements （LREE）, large ion lithophile elements （LILE, e.g., Rb, Th, U and Pb）, and depleted relatively in HFSE （e.g., Nb, Ta and Yb） without significant Eu and Ce negative anomalies. The slightly higher than modern primitive mantle initial 875r/86Sr ratios, lower εNd（/） values, relatively uniform 206pb/204pb ratios of the porphyries in the studying area, indicate that they were probably generated from partial melting of the garnet amphibolite and/or amphibolite eclogite, followed by a low degree of crystal fractionation and crustal contamination during the magma ascending and intrusion. We suggest that the formation of the Yulong large porphyry copper deposit belt is related to the Toba-Mangkang sinistral strike-slip fault （TBF） in the Red River-Ailaoshan fracture system caused by the India-Asia continental collision in middle Eocene of early Tertia
出处
《大地构造与成矿学》
EI
CAS
CSCD
北大核心
2013年第3期440-454,共15页
Geotectonica et Metallogenia
基金
国家自然科学基金(批准号:4053019)
广州市科技计划项目(编号:2012420004205008)
广东省高校海洋石油勘探开发重点实验基金(42000-3211101)联合资助
关键词
富碱斑岩
地球化学特征
成矿机制
玉龙铜矿带
藏东
alkali-rich porphyry
geochemical characteristics
metallogenic mechanism
Yulong copper belt
eastern Tibet
