Non-Newtonian rheology of crystal-bearing magmas and implications for magma ascent dynamics

Caricchi, Luca; Burlini, L.; Ulmer, Peter; Gerya, Taras; Vassalli, M.; Papale, Paolo

doi:10.1016/j.epsl.2007.09.032

Cited by 391 publications

(403 citation statements)

References 42 publications

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“…Recently Hess et al [2008] hypothesized that the apparent non-Newtonian rheology in these experiments is caused by temperature generated through viscous deformation and not by an inherent shear-thinning behavior of the materials. On the other hand, Lavallee et al [2007] and Caricchi et al [2007] attributed the shear-thinning behavior observed in their experiments to the existence of crystals in the magma.…”

Section: Introductionmentioning

confidence: 99%

Brittleness of fracture in flowing magma

Ichihara

Rubin

2010

J. Geophys. Res.

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[1] Understanding the transition to brittle fracture of flowing magma is essential for estimating the explosiveness of a volcanic eruption. In order to quantify brittleness of flowing magma, a new parameter b is introduced, which is a function of the ratio of the rate of change of the strain energy due to elastic distortional deformation to the mechanical power due to total distortional deformation rate. From the perspective of b, dependence of brittle fracture of magma on stress, decompression rate, strain rate, and shear-thinning effects are reviewed. The experimental data of Kameda et al. (2008) for rapid decompression of simulants of bubbly magma have also been reexamined. The results show that b exhibits a strong transition that correlates well with the observed transition between ductile expansion to brittle fragmentation. Moreover, b is useful in considering the effects of shear-thinning and steady-creep conditions on brittle fracture. Statements in the literature that suggest that materials behave in a brittle manner at sufficiently high strain rate are correct. However, these statements do not precisely quantify the notion of high strain rate so they are easy to misinterpret when considering the effect of shear thinning. Although shear thinning tends to increase the absolute magnitude of the total strain rate, it does not necessarily increase brittleness. Also, in principle, it is unlikely for brittle fracture to occur at steady creep. Cracking observed in steady-creep experiments of magma (Lavallee et al., 2007 may be attributed to small fluctuations with sufficiently high frequencies to satisfy the conditions for brittle fracture.

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Section: Introductionmentioning

confidence: 99%

Brittleness of fracture in flowing magma

Ichihara

Rubin

2010

J. Geophys. Res.

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“…However, the experimental data show that natrocarbonatitic magmas crystallize rapidly during cooling at atmospheric pressure. Thus, it is possible that syn-emplacement crystallization may affect the behavior of natrocarbonatitic lavas during emplacement as the crystal content has been shown to significantly increase the viscosity (Lejeune and Richet 1995;Caricchi et al 2007Caricchi et al , 2008.…”

Section: Textural Coarsening Of Gregoryitesmentioning

confidence: 99%

“…Since degree of crystallinity does not seem to be the main factor controlling the morphologies for the natrocarbonatitic flows observed in the field, we performed an extremely simplified modeling to qualitatively estimate the effect of slope on the flow behavior for natrocarbonatitic lavas containing 60 and 70 vol.% crystals. Crystal-rich magmas are characterized by non-Newtonian behavior, and thus, the slope (which affects the stress applied to the magma) can have a strong control on the viscosity of such lavas (Caricchi et al 2007(Caricchi et al , 2008. In the calculations, we have considered a lava flow of 0.3 m thickness (h), driven only by gravity.…”

Section: Textural Coarsening Of Gregoryitesmentioning

confidence: 99%

Experimental constraints on the crystallization of natrocarbonatitic lava flows

Mattsson

Caricchi

2009

Bull Volcanol

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Natrocarbonatitic magmas are characterized by their extremely low viscosities and fast elemental diffusion, and as a consequence of this, their chemistry and crystallinity can change significantly during residence in shallow reservoirs or even due to cooling during lava flow emplacement. Here, we present the results of a series of crystallization experiments conducted at 1-atm confining pressure and in a temperature range between 630°C and 300°C. The experiments were set up to characterize the chemistry and growth processes of the phenocryst phases present in natrocarbonatites. The results are applicable to (1) processes occurring during residence in shallow magma reservoirs and/or (2) during lava flow emplacement. We show that during crystallization of natrocarbonatites at atmospheric pressure, gregoryite is the first mineral to crystallize at 630°C, followed by nyerereite at 595°C. Crystal size distributions of the gregoryites show that the crystals grow rapidly by textural coarsening (i.e., Ostwald ripening). As the crystallization is a continuous process at this pressure, the composition of the residual melt changes in response to the crystallization. However, the experiments also show that individual crystals completely reequilibrate with the changes in melt composition in as little time as <11 min. We therefore conclude that crystallization and diffusion are extremely fast processes in the natrocarbonatitic system and that the measured chemical variations in phenocrysts from Oldoinyo Lengai can be explained by different cooling histories. Finally, we model the rheological control on the emplacement of highly crystallized natrocarbonatitic lavas at Oldoinyo Lengai.

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“…[21] Recent publications, such as Caricchi et al [2007] show that the magma behavior is also highly dependent on the strain rate considered and for high values (above 10 −4 s −1 ) the overall magma viscosity decreases with strain rate exhibiting non-Newtonian behavior. In that case, the velocity profile should depart from the Poiseuille parabolic profile affecting values of the shear stress at the conduit wall.…”

Section: Main Limitationsmentioning

confidence: 99%

Conditions for detection of ground deformation induced by conduit flow and evolution

et al. 2011

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[1] At mature andesitic volcanoes, magma can reach the surface through the same path for several eruptions thus forming a volcanic conduit. Because of degassing, cooling, and crystallization, magma viscosity increase in the upper part of the conduit may induce the formation of a viscous plug. We conducted numerical simulations to quantify the deformation field caused by this plug emplacement and evolution. Stress continuity between Newtonian magma flow and elastic crust is considered. Plug emplacement causes a ground inflation correlated to a decrease of the magma discharge rate. A parametric study shows that surface displacements depend on three dimensionless numbers: the conduit aspect ratio (radius/length), the length ratio between the plug and the conduit, and the viscosity contrast between the plug and the magma column. Larger displacements are obtained for high-viscosity plugs emplaced in large aspect ratio conduits. We find that only tiltmeters or GPS located close to the vent (a few hundred meters) might record the plug emplacement. At immediate proximity of the vent, plug emplacement might even dominate the deformation signal over dome growth or magma reservoir pressurization effects. For given plug thicknesses and viscosity profiles, our model explains well the amplitude of tilt variations (from 1 to 25 mrad) measured at Montserrat and Mt. St. Helens. We also demonstrate that at Montserrat, even if most of the tilt signal is due to shear stress induced by magma flow, pressurization beneath the plug accounts for 20% of the signal.

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Non-Newtonian rheology of crystal-bearing magmas and implications for magma ascent dynamics

Cited by 391 publications

References 42 publications

Brittleness of fracture in flowing magma

Brittleness of fracture in flowing magma

Experimental constraints on the crystallization of natrocarbonatitic lava flows

Conditions for detection of ground deformation induced by conduit flow and evolution

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