TRANSPORT AND EMPLACEMENT OF A MONOGENETIC LAVA FLOW AT ICE SPRINGS VOLCANIC FIELD, BLACK ROCK DESERT, UTAH

Ice Springs Volcanic Field (ISVF) is a young, 20km² monogenetic basalt field located in Utah’s Black Rock Desert, which is a region of recent geothermal interest to the Utah Geological Survey. Previous ISVF researchers, such as Hoover (1974), Lynch and Nash (1980), Thompson (2009) and College of Wooster students (2012-present) have completed geochemical work as well as interpretations of flow morphology, inflation and chronology. This work, west of the central cone complex, utilizes detailed DGPS mapping, geochemical analysis and descriptive observations of physical volcanology to outline a more detailed flow emplacement history than previously documented.

Proximal to the cones, the flow surface alternates between high terraces and low anastomosing channels, separated by vertical walls between 2 to 3 m high. DGPS mapping shows that the primary mode of lava transport in the high elevation terraces was through lava tubes and channels within the flow itself, making the channels younger than the terraces. Mapped collapsed lava tubes run sub-parallel to one another and to the walls of the channels. Lava textures in the channels show a transition from pāhoehoe to ‘a’ā where the channel narrows, produced by the high shear force from channelized lava transport. Near-vertical striations found along the walls of the channels are interpreted as falling or sliding basalt into the open channel.

More distal to the cone complex, a large channel is the conduit to a sizeable, depressed area. The vertical depression walls have an internal stratigraphy of stacked pāhoehoe lobes showing surface oxidation. Monoclinic terraces that contain tilted slabs of columnar jointed basalt that grade continuously into the depression’s floor cover the northwestern walls. A flat-topped mound in the depression's center shows similar monoclinic sides and internal stratigraphy. Striations measured on the mound and depression walls are similar to those on the channel walls. The depression floor includes inflationary features, including tumuli and pressure ridges adjacent to the walls.

At ISVF, transport mechanisms include an evolution of terraces composed of lava tubes, anastomosing channels, and inflation features. Inflation is obvious across much of the entire flow west of the cone complex and accounts for significant topographic variation.