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Rheological properties of basaltic lavas at sub-liquidus temperatures: laboratory and field-measurements on lavas from Mount Etna.

Pinkerton, Harry and Norton, G. E. (1995) Rheological properties of basaltic lavas at sub-liquidus temperatures: laboratory and field-measurements on lavas from Mount Etna. Journal of Volcanology and Geothermal Research, 68 (4). pp. 307-323. ISSN 0377-0273

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Abstract

Models of many magmatic processes require accurate data on the rheological properties of lava at sub — liquidus temperatures. Laboratory measurements of the rheological properties of basalts erupted on Mount Etna in 1983 were made at various crystal concentrations in a specially designed furnace using a Haake Rotovisco viscometer attached to a spindle designed to eliminate slippage at the melt-spindle interface. Measurements were made at strain rates between 0.3 and 5 s−1 over the range of eruption temperatures on Mount Etna (1084–1125 °C). At temperatures above 1120 °C, the 1983 lava behaves as a Newtonian fluid. At lower temperatures, the lava is a thixotropic, pseudoplastic fluid with a maximum yield strength of 78 Pa at a temperature of 1087 °C. In view of its low yield strength over this temperature range, the Theological behaviour of the lava approximates to that of a power law fluid. Apparent viscosities at unit shear strain rates increase from 150 Pa s at 1125 °C to 3000 Pa s at 1084 °C. Unit strain rate apparent viscosities measured in the field using a rotating vane viscometer range from 1385 Pa s to 1630 Pa s. These values are in close agreement with those measured at the same temperature in the laboratory and with those calculated theoretically from the physico-chemical properties of the lava.

Item Type: Article
Journal or Publication Title: Journal of Volcanology and Geothermal Research
Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
Departments: Faculty of Science and Technology > Lancaster Environment Centre
ID Code: 22321
Deposited By: ep_ss_importer
Deposited On: 05 Feb 2009 15:23
Refereed?: No
Published?: Published
Last Modified: 26 Jul 2012 15:59
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/22321

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