The response of a dune succession from Lençóis Maranhenses, NE Brazil, to climate changes between MIS 3 and MIS 2. (30th January 2020)

• Record Type: Journal Article
• Authors: Zular, André; Sawakuchi, André O.; Wang, Hong; Guedes, Carlos C.F.; Hartmann, Gelvam A.; Jaqueto, Plínio F.; Chiessi, Cristiano M.; Cruz, Francisco W.; Giannini, Paulo C.F.; Daros, Vinícius K.; Atencio, Daniel; Trindade, Ricardo I.F.
• Is Part Of: Quaternary international. Volume 537(2020)
• Page Start: 97
• Page End: 111
• Publication Date: 2020-01-30
• Subjects: Lençóis maranhenses dunefield -- Heinrich stadials -- Last glacial maximum -- Paleoclimate -- Coastal eolian deposits -- Optically stimulated luminescence -- Multy-proxy approach; Geology, Stratigraphic -- Quaternary -- Periodicals; Stratigraphie -- Quaternaire -- Périodiques; 551.79
• DOI: 10.1016/j.quaint.2019.12.012
• Languages: English
• ISSNs: 1040-6182

Abstract

Abstract: In tropical Southern Hemisphere South America, late Quaternary marine core and speleothem records provide different proxies and accurate chronologies correlating millennial-scale intervals of increased precipitation with southward shifts of the Intertropical Convergence Zone (ITCZ). However, the climatic effect of these intervals on coastal landforms is poorly understood. Here we investigated the response of abrupt and long-lasting climate events during the Marine Isotope Stages 3 and 2 in a 13.8-m thick sand succession located in a large-scale coastal eolian system, the Lençóis Maranhenses Dunefield, NE Brazil, where winds and precipitation are anti-phased and controlled by the single action of the ITCZ. A chronology of the sediment overburden determined by optically stimulated luminescence (OSL) dating of 14 sediment samples obtained at 1-m intervals showed ages between 132.2 ± 7.0 and 12.9 ± 0.6 thousand years ago in stratigraphic order. A multi-proxy approach based on grain size, surface grain texture, heavy minerals, thermoluminescence (TL) sensitivity, inorganic geochemistry, reflectance, and magnetic parameters from 268 sediment samples collected at 5-cm intervals indicated periods of dune building and stabilization. Significant stabilization periods are synchronous with Heinrich Stadials 6, 4, 3, 2, and 1, and Greenland Stadial 4, within age model uncertainties. Heavy mineral analysis indicated a steady sand source to the dune succession, while TL sensitivity analysis of quartz grains showed the input allochthonous sediments during stadials. The preservation of peak dune activity during the Last Glacial Maximum is attributed to the enduring precipitation brought by the subsequent Heinrich Stadial 1 event. Highlights: A 13.8-m stabilized eolian deposit in the Lençóis Maranhenses Dunefield was investigated. A multi-proxy approach was essential in determining periods of dune-building and stabilization. Periods of dune stabilization are synchronous with stadial events of MIS3–MIS2.