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3D Reconstruction of the Source and Scale of Buried Young Flood Channels on Mars

Science  03 May 2013:
Vol. 340, Issue 6132, pp. 607-610
DOI: 10.1126/science.1234787

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Seeing Below the Surface

Marte Vallis represents the largest of the young outflow channels on Mars. Thought to be the result of an ancient megaflood that occurred during a period that is otherwise known to be cold and dry, this channel system extends more than approximately 1000 kilometers in length and 100 kilometers in width. The channels' depths are unknown, however, because they have been covered by lava flows. By using the SHARAD radar sounder on the Mars Reconnaissance Orbiter, Morgan et al. (p. 607, published online 7 March) produced a three-dimensional reconstruction of the subsurface channels. The channels are twice as deep as previously thought and the floodwaters came from the Cerberus Fossae extensional fracture system.

Abstract

Outflow channels on Mars are interpreted as the product of gigantic floods due to the catastrophic eruption of groundwater that may also have initiated episodes of climate change. Marte Vallis, the largest of the young martian outflow channels (<500 million years old), is embayed by lava flows that hinder detailed studies and comparisons with older channel systems. Understanding Marte Vallis is essential to our assessment of recent Mars hydrologic activity during a period otherwise considered to be cold and dry. Using data from the Shallow Radar sounder on the Mars Reconnaissance Orbiter, we present a three-dimensional (3D) reconstruction of buried channels on Mars and provide estimates of paleohydrologic parameters. Our work shows that Cerberus Fossae provided the waters that carved Marte Vallis, and it extended an additional 180 kilometers to the east before the emplacement of the younger lava flows. We identified two stages of channel incision and determined that channel depths were more than twice those of previous estimates.

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