气候变化领域集成服务门户(CCPortal): Copper-mineralised porphyries sample the evolution of a large-volume silicic magma reservoir from rapid assembly to solidification

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DOI	10.1016/j.epsl.2021.116877
	Copper-mineralised porphyries sample the evolution of a large-volume silicic magma reservoir from rapid assembly to solidification
	Large S.J.E.; Buret Y.; Wotzlaw J.F.; Karakas O.; Guillong M.; von Quadt A.; Heinrich C.A.
发表日期	2021
ISSN	0012821X
卷号	563
英文摘要	Volatile-rich intermediate to silicic magmatic systems can feed devastating volcanic eruptions but also generate valuable magmatic-hydrothermal ore deposits that supply most of the world's copper. Understanding the geometry, dynamics and timescales of these magmatic systems is critical in developing models for predicting the occurrence of ore deposits and future large volcanic eruptions. Here, we use zircon petrochronology from an equigranular monzonite and successively emplaced porphyry dykes to reconstruct the time – temperature – composition evolution of the magma that sourced the giant Cu-Mo-Au deposit at Bingham Canyon (USA). Combining high-precision CA-ID-TIMS geochronology with in-situ trace element analyses by LA-ICP-MS shows the intra-grain, inter-sample and temporal geochemical changes recording the evolution of the magmatic system over 817 ± 62 kyr. Systematic variation of zircon chemistry with time indicates crystallisation from a coherent magma reservoir. After reservoir assembly its thermal and chemical state was controlled by protracted monotonous crystallisation over ∼650 kyr with rapid cooling over the first 200 kyr followed by a longer period approaching the granite solidus. Porphyry Cu-Au ore formation occurred after the early drop in magma temperature that resulted in large-scale fluid saturation and expulsion into the sub-volcanic environment but main Mo-mineralisation occurred after protracted low-temperature magma storage and the emplacement of the last porphyry. Zircons do not quantify the depth of this reservoir but integrating independent geophysical evidence with 2-D thermal modelling indicates that the time – temperature evolution recorded by the zircons is consistent with rapid incremental assembly of this large pluton (magma emplacement rate ≳ 0.0065 km3/yr) by initially zircon-undersaturated monzonitic magma into pre-heated upper crust. Our results indicate that massive fluid expulsion from rapidly-formed, large magma reservoirs containing mobile but mushy magma (>40 wt.% melt) can occur in the upper crust, favouring the formation of giant porphyry copper deposits. © 2021 The Author(s)
关键词	copper porphyry magma reservoir petrochronology thermal modelling timescale zircon
英文关键词	Binary alloys; Copper alloys; Copper deposits; Deposits; Geochronology; Gold alloys; Gold deposits; Lead alloys; Mineralogy; Molybdenum alloys; Molybdenum compounds; Ores; Temperature; Ternary alloys; Trace elements; Zircon; Copper porphyry; Large volumes; Magma reservoirs; Magmatic systems; Petrochronology; Thermal model; Time-scales; Time-temperature; Upper crust; Volcanic eruptions; Volcanoes; chronology; copper; magma chamber; ore deposit; petrology; porphyry; solidification; timescale; volcanic eruption; zircon; Bingham Canyon Mine; United States; Utah
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/203177
作者单位	Department of Earth Sciences, Eidgenössische Technische Hochschule (ETH) Zurich, Zürich, 8092, Switzerland; Faculty of Mathematics and Natural Sciences, University of Zurich, Zürich, 8006, Switzerland
推荐引用方式 GB/T 7714	Large S.J.E.,Buret Y.,Wotzlaw J.F.,et al. Copper-mineralised porphyries sample the evolution of a large-volume silicic magma reservoir from rapid assembly to solidification[J],2021,563.
APA	Large S.J.E..,Buret Y..,Wotzlaw J.F..,Karakas O..,Guillong M..,...&Heinrich C.A..(2021).Copper-mineralised porphyries sample the evolution of a large-volume silicic magma reservoir from rapid assembly to solidification.Earth and Planetary Science Letters,563.
MLA	Large S.J.E.,et al."Copper-mineralised porphyries sample the evolution of a large-volume silicic magma reservoir from rapid assembly to solidification".Earth and Planetary Science Letters 563(2021).