超大型斑岩成矿系统浅部岩浆储库时空结构——来自西藏甲玛矿区3000m科学深钻的证据

Temporal-spatial structure of shallow magma reservoir of giant porphyry metallogenic system——Evidence from 3000 m scientific deep drilling at Jiama deposit,Xizang

林彬 ¹唐菊兴 ¹唐攀 ²王梦蝶 ¹李发桥 ¹傅渊慧 ³杨征坤 ³孙渺 ⁴祁婧 ⁵王志超 ⁵徐书慧¹

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作者信息

1. 中国地质科学院矿产资源研究所自然资源部成矿作用与资源评价重点实验室,北京 100037;中国地质科学院自然资源部深地科学与探测技术实验室,北京 100094
2. 西南科技大学环境与资源学院固体废物处理与资源化教育部重点实验室,四川绵阳 621010
3. 西藏华泰龙矿业开发有限公司,西藏拉萨 850212
4. 中国地质调查局成都地质调查中心,四川成都 610081
5. 中国地质大学(北京)地球科学与资源学院,北京 100083
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摘要

近年来,碰撞型斑岩成矿系统的深部动力学机制、岩浆源区演化以及成矿物质来源已经有了较为清晰的理论认识,但对浅部岩浆储库(3～5 km)的精细地质结构、演化过程及其对斑岩成矿作用的制约机制尚不清楚.文章以西藏甲玛超大型斑岩成矿系统为实例,基于矿区成功实施的3000 m科学深钻,通过详细的地质编录,揭示甲玛斑岩成矿系统3000 m以浅的地质信息和浅部岩浆储库地质结构.同时,基于不同期次岩脉的穿切关系以及年代学分析,精细刻画了成矿系统浅部岩浆储库的时空结构,并建立了中新世(～15 Ma)多期次快速脉冲的岩浆演化模型.其中,锆石SIMS U-Pb测年揭示暗色石英闪长玢岩侵位时间为(14.9±0.1)Ma,略晚于二长花岗斑岩(15.534 Ma)、花岗闪长斑岩(15.368 Ma)的侵位时间,暗色石英闪长玢岩的蚀变与矿化特征表明其为重要的成矿岩脉.最后,浅部岩浆储库的不同期次岩脉的时空格架、矿化和蚀变特征,以及中酸性岩脉中广泛出现的暗色包体、石英溶蚀结构和大量再循环晶等证据,证实了甲玛斑岩成矿系统存在多级岩浆活动、多期次热液演化或基性岩浆持续补给,上述过程是控制铜多金属成矿的关键因素.

Abstract

In recent years,the deep dynamic mechanism,magma evolution and ore source of porphyry system at colli-sion setting have been deciphered clearly,but the fine geological structure and evolution of shallow magma reser-voir(3～5 km)and its constraint mechanism on porphyry mineralization are still obscure.Here,take the Jiama gi-ant porphyry system in Xizang as an example,based on the 3000 m scientific deep drilling,and detailed core log-ging,to reveal the geological information of shallow magma reservoir at the Jiama porphyry system.At the same time,based on the crosscutting relationship of different intrusions and geochronology,the spatiotemporal struc-ture of the shallow magma reservoir of this metallogenic system is finely defined.Then,a multipulsed evolution model of magma chamber in the Miocene(～15 Ma)is established.Zircon SIMS U-Pb dating indicated that the dark quartz diorite porphyry emplaced at(14.9±0.1)Ma,slightly later than emplacement of the monzogranite por-phyry(15.534 Ma)and granodiorite porphyry(15.368 Ma).Its alteration and mineralization suggest that it is an important ore-forming intrusion.Finally,based on the temporal and spatial framework,mineralization and altera-tion characteristics of different intrusions in shallow magma reservoirs,as well as the widespread mafic micro-granular enclaves,abundant feldspar antecrysts and dissolution texture of quartz phenocryst in intermediate-felsic intrusive dykes,it is confirmed that there exist multiple magmatism,multiple hydrothermal evolution or continu-ous mafic magma feeding in the Jiama porphyry metallogenic system,and these process is the key factors control-ling copper polymetallic mineralization.

关键词

岩浆储库/时空结构/斑岩成矿系统/甲玛/西藏

Key words

magma reservoir/temporal and special structure/porphyry metallogenic system/Jiama/Xizang

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出版年

2024

矿床地质

中国地质学会矿床地质专业委员会中国地质科学院矿床地质研究所

矿床地质

CSTPCD北大核心

影响因子：2.163

ISSN：0258-7106

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