HR: 09:00h
AN: V31D-06    [Abstracts]
TI: Lava flow-field emplacement at Rock Corral Butte, Eastern Snake River Plains, Idaho: It's doesn't look like Hawaii from here
AU: * Gregg, T K
EM: tgregg@geology.buffalo.edu
AF: University at Buffalo, Dept. of Geology 876 NSC, Buffalo, NY 14260-3050 United States
AU: Hughes, S
EM: hughscot@isu.edu
AF: Idaho State University, Dept. of Geology, Pocatello, ID 83209 United States
AU: Sakimoto, S E
EM: ssakimoto@nd.edu
AF: University of Notre Dame, Civil Engineering/Geological Sciences 105A Cushing Hall of Engineering, Notre Dame, IN 46556 United States
AB: Rock Corral Butte (RCB) is a basaltic shield volcano located at $43\deg$ 22.25'N, $113\deg$ 1.20'W within the Eastern Snake River Plains. The summit region is characterized by complex topography associated with late-stage eruption of spatter. Rock Corral Butte is surrounded by a large flow field ($>$16 km2) that is remarkable for its rolling, 2 to 4-m-scale topography that is superposed on large, kilometer-scale topographic terraces. The topographic highs within the flow are marked by relatively steep margins 2 to 4 m high, and flat or depressed interiors; the mounds are on the order of 5 to 10 m long and 3 to 10 m wide. These mounds may be tumuli or large lava lobes that have drained out or deflated (similar to flow-lobe tumuli observed in Icelandic shields). The mounds within the RCB flow field are distributed in distinct topographic terraces around the volcano. Initial analysis suggests that there is no significant change in petrology in the flow field with distance from the vent (up to 6 km), although the size and spatial density of the mounds decreases with distance. Preliminary research suggests that the distribution, size and morphology of these mounds at RCB are distinct from tumuli studied at Mauna Ulu, Hawaii, and are perhaps more similar to the distribution of similar features observed around Icelandic shields. This suggests that there may be fundamental differences in emplacement, and the formation of flow-field topography, at Mauna Ulu and RCB. Alternatively, a similar mechanism may create the RCB mounds as the tumuli at Mauna Ulu, but at different scales (both in time and space): tumuli at Mauna Ulu have been interpreted to require pulsating emplacement of small lava batches during the eruption along preferred pathways. If this holds true at RCB as well, it has implications for the size of lava pathways within the flow and eruption duration. We are continuing to examine and test models of flow field emplacement to constrain the behavior of RCB and similar shields along the Snake River Plains.
DE: 8429 Lava rheology and morphology
DE: 8499 General or miscellaneous
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting