Abstract

Monogenetic volcanism produces small basaltic volcanoes with an eruptive volume of less than 1 km3 and a lifespan on the order of 102 years. Recent studies of monogenetic fields have revealed previously unknown chemical and morphological variability called polycyclic behavior that necessitates the development of a new classification scheme. This study tests one such scheme devised by Németh and Kereszturi (2015) by using it as an investigatory framework to examine Ice Springs Volcanic Field (ISVF) in central Utah. ISVF is unique in the Black Rock Desert of Utah in having diverse silica concentrations that indicates polycyclic behavior. In order to apply the new classification scheme, we describe the emplacement processes, chemical variability, and eruption lengths that produced a small flow north of Miter crater. Five topographic profiles created from DGPS data are utilized to describe the morphology of the flow and reveal an emplacement history of inflation and lava tube development. The high vertical relief of the flow reveals an internal stratigraphy of inflated pahoehoe lobes interconnected by an anastomosing network of collapsed lava tubes. The evolved state of this network demonstrates that the flow experienced a steady flow rate. A sinuous central depression is identified as an incipient lava channel that was roofed over by the steady flow rate and developed into a large lava tube. We propose that this central tube represents a master tube that supplied the bulk of the lava to the distal end of the flow through the smaller anastomosing secondary tubes. Subsequent drainage and collapse of the lava tubes is evident from striae and accreted layers on the depression walls. North of the tube network the flow margins create a wide semi-circular basin, the interior of which displays features that were found to be rafted debris from an earlier pahoehoe sheet, as well as tumuli that developed from the stagnation and inflation of the flow margin. Major element geochemical analysis of samples taken from across the flow edifice demonstrates that the flow is part of a low silica group correlated to late Miter eruptions and distinct from older high silica eruptions. Differentiation lines in major element variation diagrams confirm that the two silica groups did not form as part of a single continuous magmatic process, which is interpreted as limited polycyclic behavior. Utilizing DGPS measurements of the master tube geometry and the rheology of the molten basalt, we calculate that the flow’s effusion rate was 44.8 ± 20 m3/s and constrain the length of the eruption to 6.19 ± 1.8 hours. This demonstrates that the flow advanced at a rate of 2.31 m/min, a speed comparable to the 1983 Pu’u O’o eruption of Kileaua, Hawaii. From Németh and Kereszturi’s new classification system, we conclude that Ice Springs Volcanic Field is a polymagmatic compound monogenetic volcanic field, and argue in favor of using the classification scheme both for its descriptive capabilities and as a framework for investigation

Advisor

Judge, Shelley

Department

Geology

Publication Date

2016

Degree Granted

Bachelor of Arts

Document Type

Senior Independent Study Thesis

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© Copyright 2016 Michael Williams