Gravel-mantled megaripples of the Argentinean Puna: A model for their origin and growth with implications for Mars

Research Article| November 01, 2013 Gravel-mantled megaripples of the Argentinean Puna: A model for their origin and growth with implications for Mars S.L. de Silva; S.L. de Silva † 1College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331, USA †E-mail: desilvas@geo.oregonstate.edu Search for other works by this author on: GSW Google Scholar M.G. Spagnuolo; M.G. Spagnuolo 1College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331, USA Search for other works by this author on: GSW Google Scholar N.T. Bridges; N.T. Bridges 2Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland 20723, USA Search for other works by this author on: GSW Google Scholar J.R. Zimbelman J.R. Zimbelman 3CEPS/NASM MRC 315, Smithsonian Institution, Washington, District of Columbia 20013-7012, USA Search for other works by this author on: GSW Google Scholar Author and Article Information S.L. de Silva † 1College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331, USA M.G. Spagnuolo 1College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331, USA N.T. Bridges 2Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland 20723, USA J.R. Zimbelman 3CEPS/NASM MRC 315, Smithsonian Institution, Washington, District of Columbia 20013-7012, USA †E-mail: desilvas@geo.oregonstate.edu Publisher: Geological Society of America Received: 06 May 2013 Revision Received: 05 Sep 2013 Accepted: 03 Oct 2013 First Online: 08 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 © 2013 Geological Society of America GSA Bulletin (2013) 125 (11-12): 1912–1929. https://doi.org/10.1130/B30916.1 Article history Received: 06 May 2013 Revision Received: 05 Sep 2013 Accepted: 03 Oct 2013 First Online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation S.L. de Silva, M.G. Spagnuolo, N.T. Bridges, J.R. Zimbelman; Gravel-mantled megaripples of the Argentinean Puna: A model for their origin and growth with implications for Mars. GSA Bulletin 2013;; 125 (11-12): 1912–1929. doi: https://doi.org/10.1130/B30916.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Gravel "megaripples" in the Puna of Argentina are the most extreme aeolian megaripples on Earth and are useful analogs for aeolian processes on Mars. Field observations, supplemented by experimental and numerical constraints on wind characteristics and aeolian transport, reveal their conditions of formation and growth to be an aeolian geomorphology "perfect storm."The bedforms are formed on a substrate of weakly indurated ignimbrite, aeolian deflation of which yields a bimodal lag of lithics and pumice clasts onto an undulating surface. Under normal wind conditions in this region, the lithics are organized into bedforms on local upslopes and "highs" through creep induced by the impact of saltating sand and pumice. The gravel bedforms grow through "shadowing" and trap sand and silt that is gradually kinetically sieved down to "lift" the gravel mantle upwards to form the megaripples. These observations connote that the largest features are not ripples in the sense of migrating bedforms, but rather nucleation sites of wind-transported sediment. Strong control by bedrock topography means that the largest bedform wavelengths are not a result of particle trajectories, and this complicates their comparison with other ripples and may require a new classification.Of relevance to Mars, the Puna megaripples are morphologically and contextually similar to small ripple-like transverse aeolian ridges (TARs). Moreover, the Puna gravels have similar equivalent weight (mg) to those composing granule ripples at Meridiani Planum, and their local origin may have implications for the origin of sediment in martian aeolian bedforms. Finally, the stable yet dynamic character of the Puna megaripples could help reconcile current models of TARs with periodic bedrock ridges that may be produced by aeolian erosion. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.