DOI: 10.1016/j.epsl.2020.116584
论文题名: The role of incremental magma chamber growth on ore formation in porphyry copper systems
作者: Korges M. ; Weis P. ; Andersen C.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 552 语种: 英语
中文关键词: magma chamber
; magmatic sill
; numerical modeling
; ore deposit
; pluton
; porphyry copper deposits
英文关键词: Copper deposits
; Deposits
; Ores
; Epithermal deposits
; Hydrothermal convection
; Hydrothermal fluids
; Magmatic intrusions
; Magmatic volatiles
; Multi-phase fluid flow
; Porphyry copper deposits
; Shallow subsurface
; Flow of fluids
; batholith
; hydrothermal fluid
; igneous intrusion
; magma chamber
; ore deposit
; pluton
; porphyry
; sill
英文摘要: Porphyry copper deposits are formed by fluids released from felsic magmatic intrusions of batholithic dimensions, which are inferred to have been incrementally built up by a series of sill injections. The growth of the magma chamber is primarily controlled by the volumetric injection rate from deeper-seated magma reservoirs, but can further be influenced by hydrothermal convection and fluid release. To quantify the interplay between magma chamber growth, volatile expulsion and hydrothermal fluid flow during ore formation, we used numerical simulations that can model episodic sill injections in concert with multi-phase fluid flow. To build up a magma chamber that constantly maintains a small region of melt within a period of about 50 kyrs, an injection rate of at least 1.3 x 10−3 km3/y is required. Higher magma influxes of 1.9 to 7.6 x 10−3 km3/y are able to form magma chambers with a thickness of 2 to 3 km. Such an intrusion continuously produces magmatic volatiles which can precipitate a copper ore shell in the host rock about 2 km above the fluid injection location. The steady fluid flux from such an incrementally growing magma chamber maintains a stable magmatic fluid plume, precipitating a copper ore shell in a more confined region and resulting in higher ore grades than the ones generated by an instantaneous emplacement of a voluminous magma chamber. Our simulation results suggest that magma chambers related to porphyry copper deposits form by rapid and episodic injection of magma. Slower magma chamber growth rates more likely result in barren plutonic rocks, although they are geochemically similar to porphyry-hosting plutons. However, these low-frequency sill injection events without a significant magma chamber growth can generate magmatic fluid pulses that can reach the shallow subsurface and are typical for high-sulfidation epithermal deposits. © 2020 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165084
Appears in Collections: 气候变化与战略
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作者单位: GFZ German Research Centre for Geosciences, Telegrafenberg, Potsdam, 14473, Germany; Institute of Earth and Environmental Science, University of Potsdam, Potsdam, 14476, Germany
Recommended Citation:
Korges M.,Weis P.,Andersen C.. The role of incremental magma chamber growth on ore formation in porphyry copper systems[J]. Earth and Planetary Science Letters,2020-01-01,552