DOI: 10.1016/j.epsl.2018.03.055
Scopus记录号: 2-s2.0-85045557759
论文题名: Rapid mixing and short storage timescale in the magma dynamics of a steady-state volcano
作者: Petrone C.M. ; Braschi E. ; Francalanci L. ; Casalini M. ; Tommasini S.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 492 起始页码: 206
结束页码: 221
语种: 英语
英文关键词: clinopyroxene residence time
; magma mixing
; non-isothermal Fe–Mg diffusion
; Stromboli
; volcano dynamics
Scopus关键词: Isotopes
; Mixing
; Plumbing
; Turbulent flow
; Volcanoes
; Water piping systems
; Zoning
; Magma mixing
; Nonisothermal
; Residence time
; Stromboli
; Volcano dynamics
; Magnesium compounds
; clinopyroxene
; diffusion
; iron
; magma
; magnesium
; steady-state equilibrium
; volcanic eruption
; volcano
; Italy
; Lipari Islands
; Messina [Sicily]
; Sicily
; Stromboli
英文摘要: Steady-state volcanic activity implies equilibrium between the rate of magma replenishment and eruption of compositionally homogeneous magmas, lasting for tens to thousands of years in an open conduit system. The Present-day activity of Stromboli volcano (Aeolian Islands, Southern Italy) has long been recognised as typical of a steady-state volcano, with a shallow magmatic reservoir (highly porphyritic or hp-magma) continuously refilled by more mafic magma (with low phenocryst content or lp-magma) at a constant rate and accompanied by mixing, crystallisation and eruption. Our aim is to clarify the timescale and dynamics of the plumbing system at the establishment of the Present-day steady-state activity (<1.2 ka) to pinpoint the onset of the steady-state regime. We investigated the Post-Pizzo (PP) pyroclastic sequence (∼1.7–1.5 ka) and one of the Early Paroxysms (EP) of the Present-day activity, focusing on the clinopyroxene population. Whole rock and clinopyroxene compositional variation among the PP and EP magmas is consistent with the time progression of the Stromboli system towards more mafic and lower 87Sr/86Sr compositions, pointing to the chemical and isotopic signature of the Present-day activity. Clinopyroxenes from both PP and EP record a complex history with compositional zoning that reflects growth in three different melt domains: a high-Mg# proto-lp recharging magma, a low-Mg# proto-hp resident magma, and a transient intermediate-Mg# magma. These are the result of complex turbulent flow fields and mixing regimes produced by repeated injections of the proto-lp magma in the shallow proto-hp magma reservoir. During the PP period the magmatic system was already able to regain the pre-input proto-hp composition, gradually changing toward a less evolved signature after the injection(s) of the more mafic proto-lp magma, owing to efficient (days to a few years) stirring and melt homogenisation (i.e., homogenisation time < residence time). Based upon Fe–Mg diffusion in clinopyroxene the total residence time during PP and EP periods, from the arrival of the mafic magma in the shallow system until the eruption, ranges from 1 to ∼50 years. Longer residence times (up to 150 years) have been recorded in the initial phase of the PP sequence, possibly testifying to the transition from a closed- to the open-conduit, steady-state regime of the Present-day activity. Some clinopyroxenes from the PP recorded the mafic triggering event of the feeding proto-lp magma occurring within few months to a few days before eruption. Remarkably, other clinopyroxene portions crystallised and captured the rapid timescales (a few days) of the on-going mixing and homogenisation process between the proto-lp and the proto-hp magmas leading to the eruption. The modelling of clinopyroxene zoning events at Stromboli provides evidence for growth and storage in three different melt domains, and sets robust constraints on their residence time from lp-magma recharge(s) to eruption, along with the timescales of melt homogenisation and triggering events. The lifetime history captured by Fe–Mg zoning of Stromboli clinopyroxenes suggests that the interplay between rapid mixing and short storage timescales can be a key parameter controlling the dynamics of the plumbing system of steady-state volcanoes. © 2018 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/109892
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
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作者单位: The Natural History Museum, Department of Earth Sciences, Cromwell Road, London, SW7 5BD, United Kingdom; CNR, IGG, Sezione di Firenze, Via G. La Pira, 4, Firenze, 50100, Italy; Università degli Studi di Firenze, Dipartimento di Science della Terra, Via G. La Pira, 4, Firenze, 50100, Italy
Recommended Citation:
Petrone C.M.,Braschi E.,Francalanci L.,et al. Rapid mixing and short storage timescale in the magma dynamics of a steady-state volcano[J]. Earth and Planetary Science Letters,2018-01-01,492