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Plateaus and Sinuous Ridges as the Fingerprints of Lava Flow Inflation in the Eastern Tharsis Plains of MarsThe Tharsis Montes rift aprons are composed of outpourings of lava from chaotic terrains to the northeast and southwest flank of each volcano. Sinuous and branching channel networks that are present on the rift aprons suggest the possibility of fluvial processes in their development, or erosion by rapidly emplaced lavas, but the style of lava flow emplacement throughout rift apron development is not clearly understood. To better characterize the style of lava emplacement and role of fluvial processes in rift apron development, we conducted morphological mapping of the Pavonis Mons southwest rift apron and the eastern Tharsis plains using images from the High Resolution Imaging Science Experiment (HiRISE), Mars Orbiter Camera (MOC), Context Camera (CTX), Thermal Emission Imaging System (THEMIS), and High Resolution Stereo Camera (HRSC) along with the Mars Orbiter Laser Altimeter (MOLA) Precision Experiment Data Records (PEDRs) and gridded data. Our approach was to: (1) search for depositional fans at the slope break between the rift apron and adjacent low slope plains; (2) determine if there is evidence that previously formed deposits might have been buried by plains units; (3) characterize the Tharsis plains morphologies east of Pavonis Mons; and (4) assess their relationship to the rift apron units. We have not identified topographically significant depositional fans, nor did we observe evidence to suggest that plains units have buried older rift apron units. Flow features associated with the rift apron are observed to continue across the slope break onto the plains. In this area, the plains are composed of a variety of small fissures and low shield vents around which broad channel-fed and tube-fed flows have been identified. We also find broad, flat-topped plateaus and sinuous ridges mixed among the channels, tubes and vents. Flat-topped plateaus and sinuous ridges are morphologies that are analogous to those observed on the coastal plain of Hawai'i, where lava flows have advanced from the volcano's several degree flank onto the nearly zero degree coastal plain. When local volumetric flow rates are low, flow fronts tend to spread laterally and often thicken via endogenous growth, or inflation, of the sheet-like flow units. If flow advance is restricted by existing topography into narrow pathways, inflation can be focused into sinuous, elongate ridges. The presence of plateaus and ridges-emplaced from the rift zones, across the plains to the east of Pavonis Mons-and a lack of fan-like features, or evidence for their burial, are consistent with rift apron lavas crossing a slope break with low local volumetric flow rates that led to inflation of sheet-like and tube-fed lava flows.
Document ID
20170007459
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Bleacher, Jacob E.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Orr, Tim R.
(Hawaiian Volcano Observatory HI, United States)
de Wet, Andrew P.
(Franklin and Marshall Coll. Lancaster, PA, United States)
Zimbelman, James R.
(Smithsonian Institution Washington, DC, United States)
Hamilton, Christopher W.
(Arizona Univ. Tucson, AZ, United States)
Garry, W. Brent
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Crumpler, Larry S.
(New Mexico Museum of Natural History and Science Albuquerque, NM, United States)
Williams, David A.
(Arizona State Univ. Tempe, AZ, United States)
Date Acquired
August 8, 2017
Publication Date
March 29, 2017
Publication Information
Publication: Journal of Volcanology and Geothermal Research
Publisher: Elsevier
Volume: 342
ISSN: 0377-0273
Subject Category
Lunar And Planetary Science And Exploration
Geophysics
Report/Patent Number
GSFC-E-DAA-TN45479
Funding Number(s)
CONTRACT_GRANT: 12-MDAP12-0013
CONTRACT_GRANT: NNX14AL54G
CONTRACT_GRANT: 09-MDAP09-0020
Distribution Limits
Public
Copyright
Other

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