Third Mars Polar Science Conference (2003) 8105.pdf TROPICAL MOUNTAIN GLACIERS ON MARS: EVIDENCE FOR AMAZONAIN CLIMATE CHANGE: James W. Head1, David E. Shean1, Sarah Milkovich1 and David Marchant2, 1Dept. Geol. Sci, Brown Univ., Provi- dence, RI 02912 USA, 2Dept., Earth Sciences, Boston Univ., Boston, MA 02215 USA,
[email protected] Introduction and background: Polar deposits on mon in an advanced state of glacial retreat. Spoon- Mars represent one of the most significant current vola- shaped hollows that commonly form at the head of tile reservoirs on the planet and these, together with many terrestrial rock glaciers likely arise due to excess high-latitude surface and near-surface ground ice, the sublimation in areas with incomplete debris cover as global cryosphere, possible groundwater, and small opposed to preservation by the more extensive tills amounts of atmospheric water vapor, represent compo- down valley. nents of the hydrological cycle. Recent Odyssey data Three shield volcanoes, collectively known as the Thar- have been interpreted to signify the presence of signifi- sis Montes, cap the broad Tharsis Rise, a huge center of cant amounts of near-surface ice at mid-to high latitudes volcanism and tectonism spanning almost the entire in both hemispheres [1]. These deposits, together with history of Mars. Olympus Mons is located on the flank other topography and morphology data, have been in- of the rise (Figure 1). Each of these volcanoes, although terpreted to mean that volatile-rich deposits have been largely constructed of effusive and explosive volcanic emplaced from about 30o north and south latitude to the deposits, contains a distinctive and unusual lobe, or fan- poles during obliquity excursions on the order of <35o shaped deposit on their west-northwestern flank.