Sponsor
Travel and thermoluminescence dating support was provided by NOAA Office of Sea Grant and Extramural Programs, U.S. Department of Commerce, under grant number NA76RG0476, project number R/ SD-04, and by appropriations made by the Oregon State Legislature.
Published In
Aeolian Research
Document Type
Article
Publication Date
7-2017
Subjects
Coastal dunes, Marine transgression, Continental shelf, Quaternary
Abstract
Shallow morpho-stratigraphic sections (n = 11) in each of two large coastal dune sheets including the Magdalena (7000 km2) and Guerrero Negro (8000 km2) dune sheets, from the Pacific Ocean side of Baja California Sur, Mexico, have been analyzed for dune deposit age. The shallow morpho-stratigraphic sections (∼2-10 m depth) include 11 new TL and 14C ages, and paleosol chronosequences, that differentiate cemented late Pleistocene dune deposits (20.7 ± 2.1 to 99.8 ± 9.4 ka) from uncemented Holocene dune deposits (0.7 ± 0.05 to at least 3.2 ± 0.3 ka). Large linear dune ridges (5-10 m in height) in the dune sheet interiors trend southeast and are generally of late Pleistocene age (∼70-20 ka). The late Pleistocene dune deposits reflect eolian transport of marine sand across the emerged continental shelf (30-50 km southeast distance) from low-stand paleo-shorelines (-100 ± 25 m elevation), which were locally oriented nearly orthogonal to modeled deep-water wave directions (∼300° TN). During the Holocene marine transgression, onshore and alongshore wave transport delivered remobilized shelf-sand deposits to the nearshore areas of the large dune sheets, building extensive barrier islands and sand spits. Submerged back-barrier lagoons generally precluded marine sand supply to dune sheet interiors in middle to late Holocene time, though exceptions occur along some ocean and lagoon shorelines. Reactivation of the late Pleistocene dune deposits in the dune sheet interiors lead to generally thin (1-3 m thickness), but widespread, covers of Holocene dune deposits (0.41 ± 0.05 to 10.5 ± 1.6 ka). Mechanical drilling will be required to penetrate indurated subsoil caliche layers to reach basal Pleistocene dune deposits.
DOI
10.1016/j.aeolia.2017.07.003
Persistent Identifier
https://archives.pdx.edu/ds/psu/33217
Citation Details
Peterson, C. D., Murillo-Jiménez, J. M., Stock, E., Price, D. M., Hostetler, S. W., & Percy, D. (2017). Origins of late-Pleistocene coastal dune sheets, Magdalena and Guerrero Negro, from continental shelf low-stand supply (70–20ka), under conditions of southeast littoral-and eolian-sand transport, in Baja California Sur, Mexico. Aeolian Research, 28, 13-28.
Description
This work was authored as part of the Contributor's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
Originally appeared in Aeolian Research, vol. 28, pages 13-28. © Elsevier B.V.
Available at http://dx.doi.org/10.1016/j.aeolia.2017.07.003.