The Influence of Topographic Obstacles on Basaltic Lava Flow Morphologies

Hester C. Mallonee, Brittany D. Brand, Andrew Philip deWet, Jacob E. Bleacher, Christopher Hamilton, Ryan Samuels

Research output: Contribution to conferencePresentation

Abstract

<div class="line" id="line-13"> Smooth p&amacr;hoehoe and jagged ʻaʻ&amacr; represent two end-members of a textural spectrum that reflects the emplacement characteristics of basaltic lava flows. However, many additional textures (e.g., rubbly and slabby p&amacr;hoehoe) reflect a range of different process due to lava flow dynamics or interaction with topography. Unfortunately the influence of topography on the distribution of textures in basaltic lava flows is not well-understood. The 18 &plusmn; 1.0 ka Twin Craters lava flow in the Zuni-Bandera field (New Mexico, USA) provides an excellent site to study the morphological changes of a lava flow that encountered topographic obstacles. The flow field is 0.2&ndash;3.8 km wide with a prominent central tube system that intersects and wraps around a 1000 m long ridge, oriented perpendicular to flow. Upstream of the ridge, the flow has low-relief inflation features extending out and around the ridge. This area includes mildly to heavily disrupted&nbsp;p&amacr;hoehoe with interdispersed agglutinated masses, irregularly shaped rubble and lava balls. Breakouts of ʻaʻ&amacr; and collapse features are also common. These observations suggest crustal disruption due to flow-thickening upstream from the ridge and the movement of lava out and around the obstacle. While the ridge influenced the path of the tube, which wraps around the southern end of the ridge, the series of collapse features and breakouts of ʻaʻ&amacr; along the tube system are more likely a result of changes in flux throughout the tube system because these features are found both upstream and downstream of the obstacle. This work demonstrates that topography can significantly influence the formation history and surface disruption of a flow field, and in some cases the influence of topography can be separated from the influences of changes in flux along a tube system.</div>
Original languageAmerican English
StatePublished - 15 Dec 2014
Event2014 American Geophysical Union Fall Meeting - San Francisco, CA
Duration: 17 Dec 2014 → …

Conference

Conference2014 American Geophysical Union Fall Meeting
Period17/12/14 → …

EGS Disciplines

  • Volcanology

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