The viscosity of basaltic magma; an analysis of field measurements in Makaopuhi lava lake, Hawaii

Shaw, Herbert R.; Wright, Tim; Peck, Dallas L.; Okamura, Reginald T.

doi:10.2475/ajs.266.4.225

Cited by 372 publications

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“…Shaw et al 1968;Walker 1971;Fink 1983;Webb and Dingwell 1990;Dragoni et al 1992;Manley 1992;Fink and Griffiths 1998;Manga et al 1998;Castro and Cashman 1999;Gottsmann and Dingwell 2001;Hess et al 2008;Castro et al 2013). It has been previously reported that the Rocche Rosse behaved as a Bingham fluid during emplacement (Clay et al 2013), which can promote strain localisation and folding.…”

Section: Crust Formationmentioning

confidence: 96%

Emplacement of the Rocche Rosse rhyolite lava flow (Lipari, Aeolian Islands)

2018

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The Rocche Rosse lava flow marks the most recent rhyolitic extrusion on Lipari island (Italy), and preserves evidence for a multi-stage emplacement history. Due to the viscous nature of the advancing lava (10 8 to 10 10 Pa s), indicators of complex emplacement processes are preserved in the final flow. This study focuses on structural mapping of the flow to highlight the interplay of cooling, crust formation and underlying slope in the development of rhyolitic lavas. The flow is made up of two prominent lobes, small (< 0.2 m) to large (> 0.2 m) scale folding and a channelled geometry. Foliations dip at 2-4°over the flatter topography close to the vent, and up to 30-50°over steeper mid-flow topography. Brittle faults, tension gashes and conjugate fractures are also evident across flow. Heterogeneous deformation is evident through increasing fold asymmetry from the vent due to downflow cooling and stagnation. A steeper underlying topography mid-flow led to development of a channelled morphology, and compression at topographic breaks resulted in fold superimposition in the channel. We propose an emplacement history that involved the evolution through five stages, each associated with the following flow regimes: (1) initial extrusion, crustal development and small scale folding; (2) extensional strain, stretching lineations and channel development over steeper topography; (3) compression at topographic break, autobrecciation, lobe development and medium scale folding; (4) progressive deformation with stagnation, large-scale folding and refolding; and (5) brittle deformation following flow termination. The complex array of structural elements observed within the Rocche Rosse lava flow facilitates comparisons to be made with actively deforming rhyolitic lava flows at the Chilean volcanoes of Chaitén and Cordón Caulle, offering a fluid dynamic and structural framework within which to evaluate our data.

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Section: Crust Formationmentioning

confidence: 96%

Emplacement of the Rocche Rosse rhyolite lava flow (Lipari, Aeolian Islands)

2018

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“…The occurrence of significant convection or advection in passive, or inactive lava lakes (see definition in Harris et al, 2005;Swanson et al, 1979) is heavily more debated (e.g. Davaille and Jaupart, 1993;Evans and Moore, 1968;Hermance and Colp, 1982;Hort et al, 1999;Jellinek and Kerr, 2001;Moore and Evans, 1967;Rupke and Hort, 2004;Shaw et al, 1968;Worster et al, 1993;Wright and Okamura, 1977). Below, we will only use the term 'convection' for the purpose of simplification.…”

Section: Convective or Advective Redistribution Of Crystalsmentioning

confidence: 99%

Mécanismes de solidification des magmas basaltiques :

Vinet¹

2010

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PAR NICOLAS VINET MÉCANISMES DE SOLIDIFICATION DES MAGMAS BASALTIQUES : ÉTUDE QUANTITATIVE TEXTURALE ET GEOCHIMIQUE DES LAVES DU VOLCAN KILAUEA, HAWAII NOVEMBRE 2010 11 RÉSUMÉLe volcan Kilauea, Hawaii, est probablement le système magmatique basaltique actif le plus étudié sur Terre, et représente donc un site privilégié pour l'étude des processus de solidification basaltique en milieu naturel. Une meilleure compréhension de la solidification magmatique est d'importance majeure dans le raffinement de modèles expliquant le dynamisme des chambres magmatiques, et son étude détaillée est susceptible de grandement améliorer notre connaissance de l'évolution globale des systèmes magmatiques. Dans ce contexte volcanique, les lacs de lave offrent une rare opportunité d'étudier directement la solidification magmatique et peuvent être considérés, en première approximation, comme des analogues superficiels de petites chambres magmatiques.Le but premier de ce doctorat est de déterminer et quantifier les principaux processus de solidification magmatiques à l'oeuvre dans la genèse des basaltes tholéiitiques. Ce travail s'articule autour du minéral olivine comme composant central. Dans les deux premiers chapitres, l'approche est double, texture et géochimie, mais l'emphase porte sur l'aspect textural dont l'analyse de la distribution de la taille des cristaux (CSD) est la composante phare. Ce travail a été réalisé sur les laves produites par les éruptions de 1969 (Mauna Ulu) et 1959 du volcan Kilauea. L'étude des coulées de lave produites par l'éruption du Mauna Ulu permet de mieux comprendre les processus actifs de solidification dans tout le système magmatique superficiel (la "tuyauterie") de l'édifice. L'étude du lac de lave Kilauea Iki renseigne quant à elle sur la solidification en système semi-fermé en sub-surface. Dans un dernier temps, il est question d'évaluer plus en détail l'influence de la déformation magmatique sur la structure interne des divines, et de la quantifier, en utilisant une technique in situ récente de micro-diffraction des rayons X. Chacun des trois chapitres de cette thèse est un article publié ou destiné à la publication dans une revue scientifique internationale.L'article 1 présente les résultats en éléments majeurs et traces (roche totale), les compositions de l'olivine, et les CSDs de 11 échantillons de laves du Mauna Ulu. Les variations chimiques en roche totale sont interprétées comme étant partiellement produites par addition d'olivine dans le système magmatique. Les profiles CSD suggèrent qu'au moins deux populations d'olivines interviennent : (1) une population d'âges 3-40 ans, caractérisée par une faible densité de "gros" cristaux et des pentes CSD relativement faibles ; et (2) une population d'âges 1,5-15 ans, marquée par une forte densité de petits cristaux et des pentes CSD plus fortes. La gamme de compositions de l'olivine suggère que ces cristaux se sont formés à partir de magmas différents, probablement reliés par crystallisation fractionnée. La présence d'olivines déformées de toutes ...

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“…The shear intensity decreases progressively from the margins towards the centre where the maximum flow velocity is attained (Merle, 1998). Variations in the profiles may be controlled by changes of particle/liquid/volatile proportions within the flowing magma (i.e., viscosity contrast between the pyroxene phenocrysts and matrix and/ or initial concentration and size distribution of particles with respect to matrix), all of which can modify the contact interactions during flow, and also by temperature and strain rates (Gay, 1968;Shaw et al, 1968;Arbaret et al, 2000).…”

Section: Conceptual Modelmentioning

confidence: 99%

“…According to Shaw (1969), the relationship between the viscosity increase as a function of temperature decrease is given by: (Shaw et al, 1968 andShaw, 1969). where T is the temperature after time t, T o = 1,200°C is the initial temperature, and η 0 = 10 2.65 poise is the viscosity at the dyke margin at a temperature T o (Fig.…”

Section: Differentiated Magma Subject To Plane Shearmentioning

confidence: 99%

Interaction between magmatic and tectonic stresses during dyke intrusion.

Skarmeta¹

2011

andgeo

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ABSTRACT. Cataclastic and mylonitic rocks exposed in the southwestern part of the Peninsula de Mejillones, northern Chile, are intruded at high angles of the foliation by younger, steeply inclined (±70°) basaltic dykes that resemble intrusive tension gashes with knife-edge contacts with the country rocks. These late dykes developed sigmoidaly-shaped, preferred orientation paths defined by oriented pyroxene phenocrysts that vary in size, aspect ratio, concentration and distribution across the width of an individual dyke. This banding has z and s asymmetries that indicate the sense of displacement of the country rock. The relative involvement of the coeval, internal and external stresses that caused the finite strains is estimated by using a partition analysis. The phenocryst location and size distribution are related to the internal magma flow velocity (u m ) stress component, whereas the sigmoid banding is linked to the external tectonic wall displacement velocity (±u). Dyke wall sliding with or against the magma flow induced the asymmetric shear strain distribution. The measured strain and displacements are analyzed using the deformation model of viscous laminar flow confined between two parallel plates moving parallel to each other with opposed motion. The shear stresses related to magma intrusion and frictional dyke-wall shear are quantified on the basis of magma flow displacements, cooling times and the temperature dependent viscosity of basalts in the linear rheology range. At the estimated depth where the intrusion and deformation occurred, the state of stress was close to being hydrostatic. This conclusion is in agreement with established models of active-collapsing volcanic centres, where bulk permeability is accommodated by means of a mesh of interconnected dykes and active faults. This interactivity tends to re-equilibrate, locally and transiently, any excess differential stress and redistributes excess magmatic pressures to create a uniform hydrostatic stress regime. RESUMEN. Interacción entre esfuerzos magmáticos y tectónicos durante la intrusión de diques. Las rocas cataclásticas y miloníticas expuestas en la parte suroeste de la Península de Mejillones del norte de Chile están intruidas por un sistema de diques basálticos de alta inclinación (±70°). Estos muestran contactos intrusivos netos, grietas de tensión e internamente una orientación sigmoidal definida por un alineamiento de fenocristales de piroxeno, los que decrecen en tamaño y concentración desde el centro hacia los bordes de los diques. A partir de la geometría de la orientación preferencial se establecen los sentidos de desplazamiento de las rocas de caja, los que corresponden a sistemas de cizalle conjugados, con asimetrías en s y z respectivamente. La participación relativa de los esfuerzos fue segregada en una componente interna o magmática y una externa o tectónica. La zonación y concentración de los fenocristales están relacionadas con el flujo magmático (u m ), mientras que la orientación sigmoidal preferente con los esfuerzos tec...

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The viscosity of basaltic magma; an analysis of field measurements in Makaopuhi lava lake, Hawaii

Cited by 372 publications

References 0 publications

Emplacement of the Rocche Rosse rhyolite lava flow (Lipari, Aeolian Islands)

Emplacement of the Rocche Rosse rhyolite lava flow (Lipari, Aeolian Islands)

Mécanismes de solidification des magmas basaltiques :

Interaction between magmatic and tectonic stresses during dyke intrusion.

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