globalchange  > 气候变化与战略
DOI: 10.1016/j.epsl.2021.116877
论文题名:
Copper-mineralised porphyries sample the evolution of a large-volume silicic magma reservoir from rapid assembly to solidification
作者: Large S.J.E.; Buret Y.; Wotzlaw J.F.; Karakas O.; Guillong M.; von Quadt A.; Heinrich C.A.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2021
卷: 563
语种: 英语
中文关键词: 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
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)
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165555
Appears in Collections:气候变化与战略

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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

Recommended Citation:
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]. Earth and Planetary Science Letters,2021-01-01,563
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