投稿时间：2024-07-16
修订日期：2024-12-06
网络发布日期：2025-01-07
中文摘要: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 collision setting have been deciphered clearly, but the fine geological structure and evolution of shallow magma reservoir (3~5 km) and its constraint mechanism on porphyry mineralization are still obscure. Here, take the Jiama giant porphyry system in Xizang as an example, based on the 3000 m scientific deep drilling, and detailed core logging, 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 structure 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 porphyry (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 alteration characteristics of different intrusions in shallow magma reservoirs, as well as the widespread mafic microgranular 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 continuous mafic magma feeding in the Jiama porphyry metallogenic system, and these process is the key factors controlling copper polymetallic mineralization.
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基金项目:本文得到国家自然基金科研项目(编号：42272093、42230813)、中国地质科学院院基本科研业务费（编号：JKYZD202316）、国家重点研发计划项目（编号：2022YFC2905001）、西藏自治区科技计划项目（编号：XZ202401YD0006）、新一轮找矿突破战略行动科技支撑项目（编号：ZKKJ202429）和中国地质调查局项目（编号：DD20230054）联合资助
引用文本：
林彬,唐菊兴,唐攀,王梦蝶,李发桥,傅渊慧,杨征坤,孙渺,祁婧,王志超,徐书慧.2024.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3000 m科学深钻的证据[J].矿床地质,43(6):1360~1379LIN Bin,TANG JuXing,TANG Pan,WANG MengDie,LI FaQiao,FU YuanHui,YANG ZhengKun,SUN Miao,QI Jing,WANG ZhiChao,XU ShuHui.2024.Temporal-spatial structure of shallow magma reservoir of giant porphyry metallogenic system——Evidence from 3000 m scientific deep drilling at Jiama deposit, Xizang[J].Mineral Deposits43(6):1360~1379
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