HR: 16:00h
AN: P34A-01 INVITED    [Abstracts]
TI: Volcanism at Aramaiti Corona, Venus
AU: * Lang, N P
EM: nlang1@utk.edu
AF: Department of Earth and Planetary Sciences, University of Tennessee, 1412 Circle Drive, Knoxville, TN 37996, United States
AU: Lopez, I
EM: ivan.lopez@urjc.es
AF: Area de Geología-ESCET, Universidad Rey Juan Carlos, Madrid, 28933, Spain
AB: Aramaiti Corona (26° S, 82° E) is a 375 km diameter volcano-tectonic structure on Venus that is characterized by 1) an annulus of concentric fractures that crosscut a suite of radial fractures and 2) a >1100 km2 flow field that consists of small (1-20 km diameter) shield edifices, long (>100 km2) lava flows, and three overlapping steep- sided domes. The small shields occur locally within the corona interior, but are predominantly associated with the radial fractures and comprise about 75% of the flow field; timing of the shields is unconstrained. Comprising the rest of the flow field are the long lava flows and domes, which erupted from the concentric fractures, and, as such, we interpret them to represent some of the latest stages of Aramaiti volcanism. The three domes occur at the origin of the longest lava flow suggesting that the flow and domes are part of the same eruptive episode. Analysis of the spatial and temporal relation of the fractures and volcanic features reveals insight into the volcanic processes that have operated at Aramaiti. To illustrate, based on interpretations for the formation of terrestrial shield fields, the large distribution of small shield edifices suggests that volcanism at Aramaiti was dominated by the discontinuous rise of small batches of magma along the radial fractures. Further, based on their association with the concentric fractures, eruption of the late stage long lava flows and domes may be due to concentric fracture formation. To illustrate, if the center of a corona collapses (thus forming the concentric fractures) into an underlying shallow magma chamber, magma would rise through the concentric fractures to the surface. This process would be broadly akin to terrestrial caldera collapse and predicts that the domes may represent a crystal-rich mush that was squeezed from the bottom of a fractionating magma chamber; such a scenario seems to be consistent with previous interpretations of steep-sided dome formation through low effusion rates. Reconnaissance mapping of Bhumidevi (17° S, 343° E) and Zemire (32° N, 312° E) Coronae reveals similar spatial and timing relations between fractures, shields, flows, and domes suggesting that the volcanic processes that occurred at Aramaiti may be common among Venusian coronae.
DE: 5464 Remote sensing
DE: 5475 Tectonics (8149)
DE: 5480 Volcanism (6063, 8148, 8450)
DE: 8148 Planetary volcanism (5480, 8450)
DE: 8429 Lava rheology and morphology
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting