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Dielectric map of the Martian northern hemisphere and the nature of plain filling materials
Author(s) -
Mouginot Jérémie,
Pommerol Antoine,
Beck Pierre,
Kofman Wlodek,
Clifford Stephen M.
Publication year - 2012
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2011gl050286
Subject(s) - geology , martian , hesperian , mars exploration program , northern hemisphere , geophysics , volcano , sedimentary rock , amazonian , volcanology , geomorphology , earth science , paleontology , astrobiology , atmospheric sciences , physics , ecology , amazon rainforest , biology
A number of observations suggest that an extended ocean once covered a significant part of the Martian northern hemisphere. By probing the physical properties of the subsurface to unprecedented depth, the MARSIS/Mars Express provides new geophysical evidences for the former existence of a Late Hesperian ocean. The Vastitas Borealis formation, located inside a putative shoreline of the ancient ocean, has a low dielectric constant compared with that of typical volcanic materials. We show that the measured value is only consistent with low‐density sedimentary deposits, massive deposits of ground‐ice, or a combination of the two. In contrast, radar observations indicate a distribution of shallow ground ice in equilibrium with the atmosphere in the south polar region. We conclude that the northern plains are filled with remnants of a late Hesperian ocean, fed by water and sediments from the outflow channels about 3 Gy ago.