Experimental determination of plagioclase and clinopyroxene crystal growth rates in an anhydrous trachybasalt from Mt Etna (Italy)

Orlando, Andrea; D’Orazio, Massimo; Armienti, Pietro; Borrini, Daniele

doi:10.1127/0935-1221/2008/0020-1841

Cited by 46 publications

(37 citation statements)

References 32 publications

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“…Theoretically, the growth rate should be higher at low undercooling with respect to high undercooling conditions, where nucleation is favored [e.g., Fenn , ; Swanson , ]. However, here we observe that the nucleation does not keep accelerating as a function of ΔT, rather it remains constant above Δ T = 20°C; and the growth rate is nearly constant as Δ T increases (as observed in Vona and Romano []) and does not show the typical bell shape curve of the growth rate versus Δ T [e.g., Fenn , ; Swanson , ; Orlando et al ., ; Arzilli and Carroll , ]. Although current models cannot explain both behaviors, the stirring may be an important factor.…”

Section: Discussionmentioning

confidence: 99%

Viscosity measurements of crystallizing andesite from T ungurahua volcano ( E cuador)

Chevrel

Cimarelli²,

deBiasi

et al. 2015

Geochem. Geophys. Geosyst.

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Viscosity has been determined during isothermal crystallization of an andesite from Tungurahua volcano (Ecuador). Viscosity was continuously recorded using the concentric cylinder method and employing a Pt‐sheathed alumina spindle at 1 bar and from 1400°C to subliquidus temperatures to track rheological changes during crystallization. The disposable spindle was not extracted from the sample but rather left in the sample during quenching thus preserving an undisturbed textural configuration of the crystals. The inspection of products quenched during the crystallization process reveals evidence for heterogeneous crystal nucleation at the spindle and near the crucible wall, as well as crystal alignment in the flow field. At the end of the crystallization, defined when viscosity is constant, plagioclase is homogeneously distributed throughout the crucible (with the single exception of experiment performed at the lowest temperature). In this experiments, the crystallization kinetics appear to be strongly affected by the stirring conditions of the viscosity determinations. A TTT (Time‐Temperature‐Transformation) diagram illustrating the crystallization “nose” for this andesite under stirring conditions and at ambient pressure has been constructed. We further note that at a given crystal content and distribution, the high aspect ratio of the acicular plagioclase yields a shear‐thinning rheology at crystal contents as low as 13 vol %, and that the relative viscosity is higher than predicted from existing viscosity models. These viscosity experiments hold the potential for delivering insights into the relative influences of the cooling path, undercooling, and deformation on crystallization kinetics and resultant crystal morphologies, as well as their impact on magmatic viscosity.

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Section: Discussionmentioning

confidence: 99%

Viscosity measurements of crystallizing andesite from T ungurahua volcano ( E cuador)

Chevrel

Cimarelli²,

deBiasi

et al. 2015

Geochem. Geophys. Geosyst.

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“…8), can provide critical information on the dynamics of the magmatic system, although an important step-forward will be represented by the ability to transform this information into quantitative or at least semi-quantitative timescales. Considering a clinopyroxene growth rate of ∼10 −8 cm s −1 , as estimated by Orlando et al (2008) for basalts of Mt Etna, and measuring the thickness of homogenisation bands and triggering events on our greyscale profile (Figs. 6e, 8, Table 1), we can have a rough glimpse of the mixing and stirring timescale.…”

Section: Implication Of Clinopyroxene Timescales On the Magma Dynamicsmentioning

confidence: 99%

Rapid mixing and short storage timescale in the magma dynamics of a steady-state volcano

Petrone

Braschi

Francalanci

et al. 2018

Earth and Planetary Science Letters

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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 87 Sr/ 86 Sr 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 triggerin...

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“…In particular, lack of exsolution features indicates magmatic origin of magnetic inclusions, as there is poor correlation between magnetic inclusions and hosting silicates [see Tarduno et al ., ]. Although the linkage between inclusion growth and hosting silicate crystallography is beyond the scope of the present article, weak grain configurational anisotropy in plagioclase is probably responsible for the independent oxide growth in plagioclase [ Brandeis et al ., ; Burkhard , ; Orlando et al ., ].…”

Section: Microscopymentioning

confidence: 99%

Geomagnetic field intensity determination from Pleistocene trachytic lava flows in Jeju Geopark

Jeong

Liu

et al. 2014

Geochem Geophys Geosyst

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[1] A composite of 28 trachytic lava flows were recovered from the Jeju Geopark Drilling Project (JGDP) in Jeju Geopark, one of the new seven wonders of Nature declared by UNESCO in 2011. Each trachytic lava flow has a tendency to increase in magnetic grain size from the rapidly cooled brecciated margin and vesicle streaked zone downward into the massive crystalline flow interiors. The brecciated margin and vesicle streaked zone of individual trachytic lava flow contains exclusively fine-grained magnetite as inclusions in plagioclase. High-fidelity paleointensity determinations were obtained from 26 (out of 224 examined) samples from JGDP cores. Temporal variation of virtual axial dipole moments (VADMs) calculated from the absolute paleointensity estimates follows the trend of sint-800 data for the interval from $80 to $360 ka. High VADM from flow 21 possibly represents real intensity peak, as previously recognized high VADM in Japan at $336 ka, in Trans-Mexican volcanism $339, and in Hawaii $340-350 ka. Perhaps such a strong magnetic intensity near $325-350 ka might be smoothed out in relative paleointensity records.

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Experimental determination of plagioclase and clinopyroxene crystal growth rates in an anhydrous trachybasalt from Mt Etna (Italy)

Cited by 46 publications

References 32 publications

Viscosity measurements of crystallizing andesite from T ungurahua volcano ( E cuador)

Viscosity measurements of crystallizing andesite from T ungurahua volcano ( E cuador)

Rapid mixing and short storage timescale in the magma dynamics of a steady-state volcano

Geomagnetic field intensity determination from Pleistocene trachytic lava flows in Jeju Geopark

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