角闪石铝压力计对西藏多龙矿集区斑岩铜矿床剥蚀速率的制约  

Restriction of aluminum-in-hornblende geobarometer on the exhumation rates of porphyry copper deposit in Duolong district, Tibet

作　　者：王婷婷[1] 杨超[1] 夏宏伟 李彦波 杨欢欢[3] 董玉杰 李超[1] 谢富伟 WANG TingTing;YANG Chao;XIA HongWei;LI YanBo;YANG HuanHuan;DONG YuJie;LI Chao;XIE FuWei(College of Earth and Planetary Sciences,Chengdu University of Technology,Chengdu 610059,China;No.5 Geological Brigade of the Tibet Bureau of Geology and Mineral Exploration and Development,Golmud 816000,China;MNR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,CAGS,Beijing 100037,China)

机构地区：[1]成都理工大学地球与行星科学学院,成都610059 [2]西藏自治区地质矿产勘查开发局第五地质大队,格尔木816000 [3]自然资源部成矿作用与资源评价重点实验室,中国地质科学院矿产资源研究所,北京100037

出　　处：《岩石学报》2025年第5期1704-1722,共19页Acta Petrologica Sinica

基　　金：重点研发项目计划(2022YFC2905002);国家自然科学基金项目(42230813、42472140);珠峰科学研究计划项目(2024ZF11426);四川省自然科学基金项目(2024NSFSC0818)联合资助详细信息。

摘　　要：近年来的研究表明斑岩铜矿成矿过程的剥蚀速率可能控制了矿床的铜品位和规模, 因此成矿过程中的剥蚀速率成为一个热门研究。本文采用角闪石铝压力计和锆石年代学对多龙矿集区出露的早白垩新鲜岩体进行了岩体侵位深度和剥蚀速率研究, 并讨论其与成矿作用的关系。角闪石压力计结果表明多龙矿集区斑岩侵入体结晶压力范围在0.56±0.09×10^(8)~1.24±0.20×10^(8)Pa之间, 深度范围为1.93±0.31~4.30±0.69km。根据前人提出的剥蚀速率计算公式, 得出多龙矿集区在116~110Ma的最小剥蚀速率为0.36~0.68km/Myr。与全球典型斑岩铜矿床剥蚀速率对比显示该速率与世界上大部分超大型斑岩铜矿床成矿期岩体的平均剥蚀速率相似, 但显著低于El Teniente矿床(约3.00km/Myr)和Butte矿床(0.50~2.00km/Myr)成矿阶段的剥蚀速率。较高的剥蚀速率既有利于流体的释放与沉淀, 但未导致矿床被完全剥蚀, 这可能是多龙矿集区能够形成大型-超大型斑岩铜矿床并保存良好的重要控制因素之一。快速剥蚀加速了岩浆的冷却和分异作用, 促进了铜等成矿物质高效地从岩浆中分离并富集在热液流体中迁移到地壳浅部。快速剥蚀引起的潜水面下降和含矿热液的快速冷却, 使浅成低温热液矿化叠加到斑岩矿化之上, 这加速了铜、金等金属的快速沉淀, 并可能引发了铜、金的活化和再富集。这一机制可能是多龙矿集区以及全球多个超大型高品位斑岩铜矿形成的关键因素之一。Recent studies have revealed that the exhumation rate during porphyry copper deposit formation may control both copper grade and deposit scale, making this parameter a key research focus. This study investigates the emplacement depth and exhumation rates of Early Cretaceous fresh intrusions in the Duolong mineral district using aluminum-in-hornblende geobarometer and zircon geochronology, while exploring their relationships with mineralization. Barometric results indicate that the crystallization pressure of the porphyry intrusions in the Duolong district ranges from 0.56±0.09×10^(8)Pa to 1.24±0.20×10^(8)Pa, corresponding to depths of 1.93±0.31km to 4.30±0.69km. Based on previously proposed formulas for calculating exhumation rates, the minimum exhumation rates during 116~110Ma in the Duolong district are determined to be 0.36km/Myr to 0.68km/Myr Comparison with global typical porphyry copper deposits shows that this rate is similar to the average exhumation rate of most super-large porphyry copper deposits during their mineralization period, but significantly lower than that of the El Teniente deposit (approximately 3.00km/Myr) and the Butte deposit (0.50~2.00km/Myr) during their mineralization stages. A relatively high exhumation rate is conducive to the release of hydrothermal fluids from deep magma into the shallow crust, without leading to their complete erosion, which may be one of the critical factors enabling the formation and good preservation of large to super-large porphyry copper deposits in the Duolong district. Rapid exhumation accelerates magma cooling and differentiation, enhancing efficient segregation of metallogenic elements (e.g. copper) from magma into hydrothermal fluids. This may also cause downward infiltration of meteoric water into hydrothermal systems, and superposition of epithermal mineralization on porphyry mineralization, which accelerated the rapid precipitation of copper, gold and other metals, and may lead to the activation and enrichment of copper and gold. These mechanism

关 键 词：剥蚀速率 多龙矿集区 角闪石铝压力计 高品位铜矿 

分 类 号：P575.1[天文地球—矿物学] P597.3[天文地球—地质学] P618.41