Evidence for a Noachian-aged ephemeral lake in Gusev Crater, Mars

Gusev crater has long been considered the site of a lake early in Martian history, but the Mars Exploration Rover Spirit found no apparent evidence of lake deposits along its 7 km traverse from 2004 to 2010. Although outcrops rich in Mg-Fe carbonate, dubbed Comanche, were discovered in the Noachian-...

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Bibliographic Details
Published in:Geology (Boulder) 2014-04, Vol.42 (4), p.359-362
Main Authors: Ruff, Steven W, Niles, Paul B, Alfano, Fabrizio, Clarke, Amanda B
Format: Article
Language:English
Subjects:
Basalt
basalts
carbonates
Columbia Hills
Craters
Deposition
ephemeral lakes
Evaporative
Extraterrestrial geology
Fluid dynamics
Freshwater
Gusev Crater
igneous rocks
Lakes
Leaching
Mars
Mars Exploration Rover
mineral assemblages
Noachian
Outcrops
paleolakes
planets
Precipitation
pyroclastics
Sedimentary geology
terrestrial planets
volcanic rocks
Volcanoes
water-rock interaction
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Summary:Gusev crater has long been considered the site of a lake early in Martian history, but the Mars Exploration Rover Spirit found no apparent evidence of lake deposits along its 7 km traverse from 2004 to 2010. Although outcrops rich in Mg-Fe carbonate, dubbed Comanche, were discovered in the Noachian-aged Columbia Hills, they were inferred to result from volcanic hydrothermal activity. We now find evidence that the alteration of the Comanche outcrops is consistent with evaporative precipitation of low-temperature, near-surface solutions derived from limited water-rock interaction with rocks equivalent to nearby outcrops called Algonquin. Additional observations show that the Algonquin outcrops are remnants of volcanic tephra that covered the Columbia Hills and adjacent plains well before emplacement of basalt flows onto the floor of Gusev crater. Water-limited leaching of formerly widespread Algonquin-like tephra deposits by ephemeral waters, followed by transport and evaporative precipitation of the fluids into the Comanche outcrops, can explain their chemical, mineralogical, and textural characteristics.
ISSN:0091-7613
1943-2682
DOI:10.1130/G35508.1