HR: 16:45h
AN: P34A-04 INVITED    [Abstracts]
TI: Fire and Ice: Lavas on Io, Cryolavas on Titan
AU: * Lopes, R M
EM: rosaly.m.lopes@jpl.nasa.gov
AF: Jet Propulsion Laboratory, California Institute of Technology, MS 183-601, 4800 Oak Grove Dr, Pasadena, CA 91109, United States
AU: Gregg, T K
EM: tgregg@geology.buffalo.edu
AF: SUNY Buffalo, Dept of Geology, 876 Natural Sciences Complex, Buffalo, NY 14260, United States
AU: Spencer, J R
EM: spencer@boulder.swri.edu
AF: Southwest Research Institute, 1050 Walnut St, Boulder, CO 80302, United States
AU: Mitchell, K L
EM: Karl.L.Mitchell@jpl.nasa.gov
AF: Jet Propulsion Laboratory, California Institute of Technology, MS 183-601, 4800 Oak Grove Dr, Pasadena, CA 91109, United States
AU: Williams, D A
EM: David.Williams@asu.edu
AF: Arizona State University, Dept of Geological Sciences, Tempe, AZ 85287, United States
AB: Volcanic flows in our solar system are remarkably varied. Io and Titan are particularly good examples of relatively large bodies that have erupted a variety of flows, ranging from basaltic and possibly sulfur and ultramafic lavas on Io to mixtures of water and possibly ammonia and methanol on Titan. These exotic extraterrestrial flows can be much different from the examples we see on Earth, but the similarities are also striking. Understanding their eruption mechanisms is important for better constraining how effusive eruptions behave on Earth under present and past conditions. Io has exceptionally long lava flows, but these are rare compared to the most common form of Ionian volcanism; lava lakes and lava flows that are confined within calderas [Lopes et al., 2004, Icarus; Gregg and Lopes, Icarus, in press]. The largest lava flows on Io can be considered analogues to continental flood basalts on Earth, being hundreds of km long and containing many different flow units. The composition of these flows on Io is thought to be either basaltic or ultramafic. Galileo results showed the largest active flow in the Solar System at Amirani [300 km long; Kezthelyi et al., 2001, JGR 106] and recent observations by the New Horizons spacecraft showed a new flow at Masubi that is about 200 km long. Ionian flows at volcanoes such as Masubi, Maui, and Prometheus generate persistently active plumes and the movement of the Prometheus plume has been related to the growth of the lava flow [Kieffer et al. 2000, Science 288]. Sulfur flows are thought to exist on Io, but are largely a by-product of silicic volcanism. On Earth, sulfur flows are rare but have formed from melting hydrothermal sulfur deposits. Flows around Emakong on Io are thought to be sulfur flows [Williams et al., 2001, JGR 106], but to date there are no measurements that can confirm their composition. Ra Patera's flows at the time of the Voyager encounter was thought to be a site of sulfur volcanism [Pieri et al., 1984, Icarus 60], but the deposits have since been covered over. Cryovolcanism is a process that has no terrestrial analogue but which appears to be widespread in the outer solar system. Features thought to be cryovolcanic have been shown on Titan's surface [Lopes et al., 2007, Icarus 186]. Cryolavas on Titan are thought to be water and ammonia, with possibly some methanol, and to have rheologies similar to those of andesites or more evolved flows on Earth. As we continue our exploration of the solar system, we need to redefine "lava flows" as a geologic process, using a planetary rather than terrestrial context.
DE: 5480 Volcanism (6063, 8148, 8450)
DE: 8450 Planetary volcanism (5480, 6063, 8148)
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting