Martian outflow channels: How did their source aquifers form, and why did they drain so rapidly?
Catastrophic floods generated ~3.2 Ga by rapid groundwater evacuation scoured the Solar System's most voluminous channels, the southern circum-Chryse outflow channels. Based on Viking Orbiter data analysis, it was hypothesized that these outflows emanated from a global Hesperian cryosphere-confined aquifer that was infused by south polar meltwater infiltration into the planet's upper crust. In this model, the outflow channels formed along zones of superlithostatic pressure generated by pronounced elevation differences around the Highland-Lowland Dichotomy Boundary. However, the restricted geographic location of the channels indicates that these conditions were not uniform. Furthermore, some outflow channel sources are too high to have been fed by south polar basal melting. Using more recent mission data, we argue that during the Late Noachian fluvial and glacial sediments were deposited into a clastic wedge within a paleo-basin located in the southern circum-Chryse region, which at the time was completely submerged under a primordial northern plains ocean [corrected]. Subsequent Late Hesperian outflow channels were sourced from within these geologic materials and formed by gigantic groundwater outbursts driven by an elevated hydraulic head from the Valles Marineris region. Thus, our findings link the formation of the southern circum-Chryse outflow channels to ancient marine, glacial, and fluvial erosion and sedimentation.
Planetary Science Institute, 1700 East Fort Lowell Road, Suite 106, Tucson, AZ 85719-2395, USA.|NASA Ames Research Center, Mail Stop 239-20, Moffett Field, CA 94035, USA.
J Alexis P
JA
Rodriguez
Department of Hydrology &Water Resources, University of Arizona, Tucson, AZ 85721, USA.
Jeffrey S
JS
Kargel
Department of Hydrology &Water Resources, University of Arizona, Tucson, AZ 85721, USA.
Victor R
VR
Baker
NASA Ames Research Center, Mail Stop 239-20, Moffett Field, CA 94035, USA.|SETI Institute, 189 Bernardo Avenue, Mountain View, CA 94043.
Virginia C
VC
Gulick
Planetary Science Institute, 1700 East Fort Lowell Road, Suite 106, Tucson, AZ 85719-2395, USA.
Daniel C
DC
Berman
Centro de Astrobiología, M-108 km 4, 28850 Madrid, Spain.|Department of Astronomy, Cornell University, Ithaca 14850 NY, USA.
Alberto G
AG
Fairén
External Geodynamics and Hydrogeology Group, Department of Geology, Autonomous University of Barcelona, 08193 Bellaterra, Barcelona, Spain.
Rogelio
R
Linares
External Geodynamics and Hydrogeology Group, Department of Geology, Autonomous University of Barcelona, 08193 Bellaterra, Barcelona, Spain.
Mario
M
Zarroca
State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Wuhan, 430070, China.
Jianguo
J
Yan
The University Museum, University of Tokyo, 113-0033, Japan.
Hideaki
H
Miyamoto
NASA Ames Research Center, Mail Stop 239-20, Moffett Field, CA 94035, USA.|SETI Institute, 189 Bernardo Avenue, Mountain View, CA 94043.
Natalie
N
Glines