Lancaster EPrints

The influence of surface clinker on the crustal structures and dynamics of 'a'ā lava flows.

Applegarth, Louisa Jane and James, Mike R. and Van Wyk de Vries, B. and Pinkerton, Harry (2010) The influence of surface clinker on the crustal structures and dynamics of 'a'ā lava flows. Journal of Geophysical Research: Solid Earth, 115 (B07210). ISSN 2169-9313

[img]
Preview
PDF (2009JB006965.pdf)
Download (728Kb) | Preview

    Abstract

    Surface structures on 'a'ā and blocky lavas reflect the internal flow dynamics during emplacement and also influence the dynamics of developing flows. To investigate the effects of brittle, clinkery 'a'ā flow crusts on flow dynamics and surface structures, we conducted sand and silicone laboratory experiments that simulated the advance of lava into a preexisting channelized flow with a surface crust. Experiments carried out with relatively thin crusts produced apparently ductile surface deformation structures, while thick crusts behaved dominantly in a brittle manner. Increased crustal thickness led to increased strength under compression but favored more disruption under tension, as the flow core welled up through tensile fractures, entraining crustal material. At lava flow fronts, upwelling and entrainment would increase heat losses by radiation and advection, respectively, resulting in a positive‐feedback cooling loop. Fracturing caused heterogeneous crustal distribution near the flow front, which resulted in lobate flow advance, despite the absence of the viscoelastic layer that has previously been inferred as the primary control on flow advance and lobe formation. We therefore conclude that the influence of a purely brittle crust on the dynamics and surface morphologies of lava flows is more significant than often thought. All of the surface structures produced in the experiments have been observed on lavas or glaciers and many also on landslides and debris flows, suggesting the results can assist in the understanding of a range of natural flows.

    Item Type: Article
    Journal or Publication Title: Journal of Geophysical Research: Solid Earth
    Additional Information: Copyright (2010) American Geophysical Union. Further reproduction or electronic distribution is not permitted
    Uncontrolled Keywords: 'a'ā ; lava flow dynamics ; lava crust structures.
    Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
    Departments: Faculty of Science and Technology > Lancaster Environment Centre
    ID Code: 27936
    Deposited By: Dr Mike R. James
    Deposited On: 26 Oct 2009 09:30
    Refereed?: Yes
    Published?: Published
    Last Modified: 21 Nov 2017 17:34
    Identification Number:
    URI: http://eprints.lancs.ac.uk/id/eprint/27936

    Actions (login required)

    View Item