Martian Fluvial Conglomerates at Gale Crater

Research areas:
Year:
2013
Authors:
  • R. M. E. Williams
  • J. P. Grotzinger
  • W. E. Dietrich
  • S. Gupta
  • D. Y. Sumner
  • R. C. Wiens
  • Nicolas Mangold
  • M. C. Malin
  • K. S. Edgett
  • S. Maurice
  • O. Forni
  • O. Gasnault
  • A. Ollila
  • H. E. Newsom
  • G. Dromart
  • M. C. Palucis
  • R. A. Yingst
  • R. B. Anderson
  • K. E. Herkenhoff
  • Stéphane Le Mouélic
  • W. Goetz
  • M. B. Madsen
  • A. Koefoed
  • J. K. Jensen
  • J. C. Bridges
  • S. P. Schwenzer
  • K. W. Lewis
  • K. M. Stack
  • D. Rubin
  • L. C. Kah
  • J. F. Bell
  • J. D. Farmer
  • R. Sullivan
  • T. Van Beek
  • D. L. Blaney
  • O. Pariser
  • R. G. Deen
  • MSL Sci Team
Journal:
SCIENCE
Volume:
340
Number:
6136
Pages:
1068-1072
Month:
MAY 31
ISSN:
0036-8075
Abstract:
Observations by the Mars Science Laboratory Mast Camera (Mastcam) in
Gale crater reveal isolated outcrops of cemented pebbles (2 to 40
millimeters in diameter) and sand grains with textures typical of
fluvial sedimentary conglomerates. Rounded pebbles in the conglomerates
indicate substantial fluvial abrasion. ChemCam emission spectra at one
outcrop show a predominantly feldspathic composition, consistent with
minimal aqueous alteration of sediments. Sediment was mobilized in
ancient water flows that likely exceeded the threshold conditions (depth
0.03 to 0,9 meter, average velocity 0.20 to 0.75 meter per second)
required to transport the pebbles. Climate conditions at the time
sediment was transported must have differed substantially from the cold,
hyper-arid modern environment to permit aqueous flows across several
kilometers,