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Rodriguez JAP, Tanaka KL, Bramson AM, Leonard GJ, Baker VR, Zarroca M. North polar trough formation due to in-situ erosion as a source of young ice in mid-latitudinal mantles on Mars. Sci Rep 2021; 11:6750. [PMID: 33767212 PMCID: PMC7994824 DOI: 10.1038/s41598-021-83329-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 01/28/2021] [Indexed: 11/24/2022] Open
Abstract
The clockwise spiral of troughs marking the Martian north polar plateau forms one of the planet’s youngest megastructures. One popular hypothesis posits that the spiral pattern resulted as troughs underwent poleward migration. Here, we show that the troughs are extensively segmented into enclosed depressions (or cells). Many cell interiors display concentric layers that connect pole- and equator-facing slopes, demonstrating in-situ trough erosion. The segmentation patterns indicate a history of gradual trough growth transversely to katabatic wind directions, whereby increases in trough intersections generated their spiral arrangement. The erosional event recorded in the truncated strata and trough segmentation may have supplied up to ~25% of the volume of the mid-latitude icy mantles. Topographically subtle undulations transition into troughs and have distributions that mimic and extend the troughs’ spiraling pattern, indicating that they probably represent buried trough sections. The retention of the spiral pattern in surface and subsurface troughs is consistent with the megastructure’s stabilization before its partial burial. A previously suggested warm paleoclimatic spike indicates that the erosion could have occurred as recently as ~50 Ka. Hence, if the removed ice was redeposited to form the mid-latitude mantles, they could provide a valuable source of near-surface, clean ice for future human exploration.
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Affiliation(s)
- J Alexis P Rodriguez
- Planetary Science Institute, 1700 East Fort Lowell Road, Suite 106, Tucson, AZ, 85719-2395, USA.
| | - Kenneth L Tanaka
- Planetary Science Institute, 1700 East Fort Lowell Road, Suite 106, Tucson, AZ, 85719-2395, USA
| | - Ali M Bramson
- Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, 550 Stadium Mall Dr, West Lafayette, IN, 47907, USA
| | - Gregory J Leonard
- Department of Planetary Sciences, Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, 85721, USA
| | - Victor R Baker
- Department of Planetary Sciences, Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, 85721, USA.,Department of Hydrology and Atmospheric Sciences, University of Arizona, Tucson, AZ, 85721, USA
| | - Mario Zarroca
- External Geodynamics and Hydrogeology Group, Department of Geology, Autonomous University of Barcelona, 08193, Bellaterra, Barcelona, Spain
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de Haas T, McArdell BW, Conway SJ, McElwaine JN, Kleinhans MG, Salese F, Grindrod PM. Initiation and Flow Conditions of Contemporary Flows in Martian Gullies. JOURNAL OF GEOPHYSICAL RESEARCH. PLANETS 2019; 124:2246-2271. [PMID: 31763111 PMCID: PMC6853261 DOI: 10.1029/2018je005899] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 07/23/2019] [Accepted: 07/26/2019] [Indexed: 06/10/2023]
Abstract
Understanding the initial and flow conditions of contemporary flows in Martian gullies, generally believed to be triggered and fluidized by CO2 sublimation, is crucial for deciphering climate conditions needed to trigger and sustain them. We employ the RAMMS (RApid Mass Movement Simulation) debris flow and avalanche model to back calculate initial and flow conditions of recent flows in three gullies in Hale crater. We infer minimum release depths of 1.0-1.5 m and initial release volumes of 100-200 m3. Entrainment leads to final flow volumes that are ∼2.5-5.5 times larger than initially released, and entrainment is found necessary to match the observed flow deposits. Simulated mean cross-channel flow velocities decrease from 3-4 m/s to ∼1 m/s from release area to flow terminus, while flow depths generally decrease from 0.5-1 to 0.1-0.2 m. The mean cross-channel erosion depth and deposition thicknesses are ∼0.1-0.3 m. Back-calculated dry-Coulomb friction ranges from 0.1 to 0.25 and viscous-turbulent friction between 100 and 200 m/s2, which are values similar to those of granular debris flows on Earth. These results suggest that recent flows in gullies are fluidized to a similar degree as are granular debris flows on Earth. Using a novel model for mass flow fluidization by CO2 sublimation we are able to show that under Martian atmospheric conditions very small volumetric fractions of CO2 of ≪1% within mass flows may indeed yield sufficiently large gas fluxes to cause fluidization and enhance flow mobility.
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Affiliation(s)
- T. de Haas
- Department of Physical GeographyUniversiteit UtrechtUtrechtThe Netherlands
- Department of GeographyDurham UniversityDurhamUK
| | - B. W. McArdell
- Swiss Federal Institute for Forest, Snow and Landscape Research WSLBirmensdorfSwitzerland
| | - S. J. Conway
- Laboratoire de Planétologie et Géodynamique, CNRS UMR 6112, Université de NantesNantesFrance
| | - J. N. McElwaine
- Department of Earth SciencesDurham UniversityDurhamUK
- Planetary Science InstituteTucsonAZUSA
| | - M. G. Kleinhans
- Department of Physical GeographyUniversiteit UtrechtUtrechtThe Netherlands
| | - F. Salese
- Department of Physical GeographyUniversiteit UtrechtUtrechtThe Netherlands
- International Research School of Planetary SciencesUniversità Gabriele D'AnnunzioPescaraItaly
| | - P. M. Grindrod
- Department of Earth SciencesNatural History MuseumLondonUK
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Guillard F, Marks B, Einav I. Dynamic X-ray radiography reveals particle size and shape orientation fields during granular flow. Sci Rep 2017; 7:8155. [PMID: 28811568 PMCID: PMC5557931 DOI: 10.1038/s41598-017-08573-y] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 07/13/2017] [Indexed: 11/17/2022] Open
Abstract
When granular materials flow, the constituent particles segregate by size and align by shape. The impacts of these changes in fabric on the flow itself are not well understood, and thus novel non-invasive means are needed to observe the interior of the material. Here, we propose a new experimental technique using dynamic X-ray radiography to make such measurements possible. The technique is based on Fourier transformation to extract spatiotemporal fields of internal particle size and shape orientation distributions during flow, in addition to complementary measurements of velocity fields through image correlation. We show X-ray radiography captures the bulk flow properties, in contrast to optical methods which typically measure flow within boundary layers, as these are adjacent to any walls. Our results reveal the rich dynamic alignment of particles with respect to streamlines in the bulk during silo discharge, the understanding of which is critical to preventing destructive instabilities and undesirable clogging. The ideas developed in this paper are directly applicable to many other open questions in granular and soft matter systems, such as the evolution of size and shape distributions in foams and biological materials.
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Affiliation(s)
- François Guillard
- School of Civil Engineering, The University of Sydney, Sydney, 2006, Australia
| | - Benjy Marks
- School of Civil Engineering, The University of Sydney, Sydney, 2006, Australia
| | - Itai Einav
- School of Civil Engineering, The University of Sydney, Sydney, 2006, Australia. .,Department of Civil, Environmental & Geomatic Engineering, Faculty of Engineering Science, University College London, London, WC1E 6BT, UK.
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