HR: 1340h
AN: P13D-1555    [Abstracts]
TI: Possible Volcanic Province in Western Promethei Terra, Mars
AU: * Raitala, J
EM: jouko.raitala@oulu.fi
AF: Astronomy, Dept. of Physical Sciences, PO Box 3000, University of Oulu, Oulu, 90014, Finland
AU: Ivanov, M
EM: Mikhail_Ivanov@Brown.edu
AF: Astronomy, Dept. of Physical Sciences, PO Box 3000, University of Oulu, Oulu, 90014, Finland
AU: Ivanov, M
EM: Mikhail_Ivanov@Brown.edu
AF: Lab. of Comparative Planetology, RAS, Vernadsky Institute, 19 Kasigyn Street, Moscow, 119991, Russian Federation
AU: Kostama, V
EM: petri.kostama@oulu.fi
AF: Astronomy, Dept. of Physical Sciences, PO Box 3000, University of Oulu, Oulu, 90014, Finland
AU: Korteniemi, J
EM: jarmo.korteniemi@oulu.fi
AF: Astronomy, Dept. of Physical Sciences, PO Box 3000, University of Oulu, Oulu, 90014, Finland
AU: Törmänen, T
EM: terhi.tormanen@oulu.fi
AF: Astronomy, Dept. of Physical Sciences, PO Box 3000, University of Oulu, Oulu, 90014, Finland
AU: Neukum, G
EM: gneukum@zedat.fu-berlin.de
AF: Institut of Geosciences, Dept. of Earth Sciences, Freie Universität, Malteserstr. 74-100, Berlin, 12249, Germany
AB: The western Promethei Terra region (36-50°S, 90-106°E) studied is roughly ~700 km across. It occupies a unique area on the smoothened eastern Hellas basin rim, and consists of two parts: a gentler (~0.07°, eastward of ~97°E) and a steeper (~0.88°, W of ~97°E) regional slope. The Noachian cratered terrain surrounds the region in the NE, E, and S. The large canyons of Harmakhis, Reull and Teviot Valles cut through the central area and the smooth Hesperian plains [1-10] of the western and central areas display a set of features that does not occur elsewhere on the eastern side of the Hellas basin. The plains have multi-layered interiors as seen on the walls of the canyons that cut them. Similar stacks of sub- horizontal layers are seen in other Martian regions with exposed lava plain interiors, for example, in Lunae Planum and Syrtis Major. These are classic volcanic provinces the layered structure of which was formed by successive emplacement of sheet lava flows that followed the general topographic trend. The average visible thickness of the Promethei layers is ~70-80 m and the typical measured canyon wall slope is ~25-30o. This gives an estimate of the thickness of the layers, which is ~35-45 m. The full layer stack thickness, estimated from observations, is ~1.3 km. Consistent with the observed layering, there are narrow wrinkle ridges (WR) that deform the surface of the plains. WR mostly occur in the eastern portion of the area near Reull and Teviot Valles but some of them are seen near Harmakhis Vallis in the west. Additional long straight narrow ridges (widths < km, heights 10s m, lengths 10s km), which occur in mostly NE-SW-oriented groups, are seen on the surface of the plains. The regional topography does not appear to control the distribution of the ridges. Their morphologic characteristics, areal distribution, and close association with the lava plains are consistent with and suggest that the straight ridges may represent exhumed dikes [11], which have served as feeders for the lava plains. The identified features and layered structure suggest that the regional basement material is of volcanic origin. The lava sheets have experienced post-emplacement compression and dike injections. The approximate volume of the layered material in this region is estimated to be ~0.3 x 106 km3 and the time of emplacement of the material may correspond to the Late Noachian-Early Hesperian epochs. References: [1] Potter (1976) USGS I-941. [2] King (1978) USGS I-1073. [3] Scott & Carr (1978) USGS I-1083. [4] Scott &. Tanaka (1986) USGS I-1802-A. [5] Greeley & Guest (1987) USGS I-1802-B. [6] Crown et al. (1992) Icarus 100, 1-25. [7] Price (1998) USGS I-2557. [8] Mest & Crown (2002) USGS I-2730. [9] Mest & Crown (2002) USGS I- 2763. [10] Leonard & Tanaka (2001) USGS I-2694. [11] Head et al. (2006) Geology 34, 285-288.
DE: 5470 Surface materials and properties
DE: 5480 Volcanism (6063, 8148, 8450)
DE: 8148 Planetary volcanism (5480, 8450)
DE: 8450 Planetary volcanism (5480, 6063, 8148)
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting