The Relationship Between Flow Facies and Topographic Obstacles in the Zuni-Bandera Lava Field, New Mexico

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Brittany Brand


The 18.0 ± 1.0 ka Twin Craters lava flow in New Mexico provides an opportunity to study morphological changes of a lava flow that encountered a topographic obstacle. Facies mapping and airborne image analysis were performed on an area surrounding a 1000 m long limestone bluff oriented perpendicular to the flow direction. A pahoehoe flow and >2.5 km long lava tube are found upstream. Within 1200 m of the bluff, emplacement characteristics changed abruptly to include localized areas of disrupted pahoehoe. Several depressions partly surrounded by a(2011.Bul Volcanol.73.335-346) in Hawai‘i. Orr suggests that shatter rings develop when fluctuating pressure causes a tube roof to repeatedly uplift.

We interpret this area to have been a lava “pond” created upstream of the limestone bluff. A network of preferred flow pathways formed within the ponded area. This system was subjected to pressurization changes, resulting in shatter ring-like features and breakouts. The lava from these breakouts rapidly underwent a change in shear stress, resulting in a rubbly flow. This study has implications for understanding lava flow dynamics, as well as the evolution of shatter rings.

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