Two modes for dune orientation

Abstract

Research Article| September 01, 2014 Two modes for dune orientation Sylvain Courrech du Pont; Sylvain Courrech du Pont * 1Laboratoire Matière et Systèmes Complexes, Sorbonne Paris Cité, Université Paris Diderot, CNRS UMR 7057, 10 rue A. Domon et L. Duquet, 75205 Paris Cedex13, France *E-mail: sylvain.courrech@univ-paris-diderot.fr. Search for other works by this author on: GSW Google Scholar Clément Narteau; Clément Narteau 2Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Université Paris Diderot, CNRS UMR 7154, 1 rue Jussieu, 75238 Paris Cedex 05, France Search for other works by this author on: GSW Google Scholar Xin Gao Xin Gao 2Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Université Paris Diderot, CNRS UMR 7154, 1 rue Jussieu, 75238 Paris Cedex 05, France Search for other works by this author on: GSW Google Scholar Geology (2014) 42 (9): 743–746. https://doi.org/10.1130/G35657.1 Article history received: 08 Mar 2014 rev-recd: 03 Jun 2014 accepted: 04 Jun 2014 first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Sylvain Courrech du Pont, Clément Narteau, Xin Gao; Two modes for dune orientation. Geology 2014;; 42 (9): 743–746. doi: https://doi.org/10.1130/G35657.1 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 SocietyGeology Search Advanced Search Abstract Earth’s sand seas (dune fields) experience winds that blow with different strengths and from different directions in line with the seasons. In response, dune fields show a rich variety of shapes, from crescentic barchans to star and linear dunes. These dunes commonly exhibit complex and compound patterns with a range of length scales and various orientations, which up to now have remained difficult to relate to wind cycles. Here, we develop a model for dune orientation that explains the coexistence of bedforms with different alignments in multidirectional wind regimes. This model derives from subaqueous experiments, which show that a single bidirectional flow regime can lead to two different dune orientations depending on sediment availability, i.e., the erodibility of the bed. Sediment availability selects the overriding mechanism for the formation of dunes: increasing in height from the destabilization of a sand bed (with no restriction in sediment availability) or elongating in a finger on a non-erodible surface from a localized sand source. These mechanisms drive the dune orientation. Therefore, dune alignment maximizes dune orthogonality to sand fluxes in the bed instability mode, while dunes are aligned with the mean sand transport direction in the fingering mode. Applied to Earth’s deserts, the model quantitatively predicts the orientation of rectilinear dunes and their superimposed patterns. This field study suggests that many linear dunes on Earth elongate from sources, and are simply aligned with the mean sand transport direction. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.