HR: 0800h
AN: V31A-0297    [Abstracts]
TI: The Dispersal of Ash From an Ancient Volcanic Center on Mars
AU: * Kerber, L A
EM: Laura_Kerber@brown.edu
AF: Brown University, Geological Sciences 324 Brook Street Box 1846, Providence, RI 02912, United States
AU: Head, J W
EM: James_Head_III@Brown.edu
AF: Brown University, Geological Sciences 324 Brook Street Box 1846, Providence, RI 02912, United States
AB: Apollinaris Patera (-8°S, 174°E) is a medium-sized martian volcano thought to have been active during the Hesperian period in Mars history. Extensive deposits near the volcano, mapped as a part of the Medusae Fossae Formation (MFF), have been dated as Amazonian. The deposits surrounding the volcano have been shown to be friable and fine grained, resulting in a wide variety of eolian landforms including long, linear dunes and yardangs. The MFF is found at both high and low elevations. These pieces of evidence have caused some to suspect that the formation is made of windblown, reworked eolian material or loess. Pedestal craters, which are thought to result from impact-induced armoring or cementing of the target material and subsequent erosion by wind or volatile sublimation, are common in the unit, although pedestal craters are usually seen in volatile-rich substrates closer to the poles. The MFF also appears similar to circumpolar deposits. This evidence has suggested that either the deposits are the result of airborne volatile-rich sediments deposited during high obliquity, or that they are themselves paleopolar deposits. The MFF lies in close proximity to Apollinaris, a volcano of considerable size; it is thus an interesting possibility that the MFF is the result of pyroclastic flows, ashfall (or some combination thereof) from Apollinaris. The MFF has been dated as Amazonian, postdating Apollinaris Patera, but there is evidence that a considerable amount of reshaping and removal of material has gone on in the Medusae Fossae region which could cause a crater count to yield an anomalously young age. We present results from a modeling study using a Mars Global Climate Model (Mars GCM) and an eruption and dispersal model to better constrain where deposits of ash erupted from Apollinaris might accumulate according to current ideas regarding eruption dynamics on Mars and modern martian global wind patterns. Mapping of deposits surrounding the volcano provides a general check of modeling results and an assessment of the viability of the ashfall hypothesis. Further work will focus on differences between current wind patterns and those present during the eruptive phase of the volcano, more than three billion years before the present.
DE: 5480 Volcanism (6063, 8148, 8450)
DE: 8404 Volcanoclastic deposits
DE: 8409 Atmospheric effects (0370)
DE: 8414 Eruption mechanisms and flow emplacement
DE: 8428 Explosive volcanism
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting