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Volume 24 Issue 2 (February 2014)

GSA Today

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Article, pp. 4-10 | Full Text | PDF (3.8 MB)

Boulders of the Vastitas Borealis Formation: Potential origin and implications for an ancient martian ocean

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Lorena Moscardelli

Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin; now at Statoil North America–Research, Development and Innovation in Austin, Texas, USA


The hypothetical existence of a martian ocean that is based on identification of alleged paleoshorelines has been heavily contested during recent years. Despite the controversy surrounding the paleoshoreline interpretation, additional evidence supporting the idea of a late Hesperian–early Amazonian martian ocean has recently been documented in areas that were potentially covered by this body of water. Most of these observations have been made by the establishment of analogies between martian features within the northern plains and depositional elements from deep-water terrestrial environments (e.g., teardrop-shaped islands, large-scale polygonal terrains, and high-albedo mounds). This paper showcases a new terrestrial, deep-water analogy that also supports the existence of an ancient martian ocean. Boulder-size rocks that are contained within the Vastitas Borealis Formation (VBF) on the northern plains of Mars are compared with boulder- and kilometer-scale blocks that have been transported subaqueously as part of mass-transport events in a multitude of terrestrial deep-water environments. These observations suggest that meter-scale rocks that make up part of the VBF might have been emplaced by catastrophic mass-transport events similar to those documented within continental margins on Earth.

Manuscript received 20 Aug. 2013; accepted 5 Sept. 2013

DOI: 10.1130/GSATG197A.1