Abstract

SUGUIO, Kenitiro; BEZERRA, Francisco H.R.  and  BARRETO, Alcina M.F.. Luminescence dated Late Pleistocene wave-built terraces in northeastern Brazil. An. Acad. Bras. Ciênc. [online]. 2011, vol.83, n.3, pp. 907-920.  Epub July 01, 2011. ISSN 0001-3765.  http://dx.doi.org/10.1590/S0001-37652011005000010.

This study presents field and chronological investigations along the coast of northeastern Brazil from ~4°S to 9°S latitude, which corresponds to ~700 km of coastline under a semi-diurnal mesotidal regime. We investigated wave-built terrace deposits and dated sediments using the optically stimulated luminescence and thermoluminescence methods on quartz grains. The wave-built terraces yielded two main age groups: 200-230 ka and 100-130 ka, which we interpreted as depositional ages. We correlated these age groups with oxygen-isotope stages 7c and 5e, respectively. These events correspond to the antepenultimate and penultimate transgressions along the Brazilian coast. The deposits occur mainly in patches on low-lying flat plateaus along the littoral zone and incision valleys that cut across coastal tablelands. The altitude of the base of the 200-230 ka terraces ranges from 10 m above mean sea level (asl) to -2m asl, whereas the base of the 100-130 ka varies from 12 m asl to -2 m asl. Both terraces were deposited in the foreshore and upper shoreface zones. We noted a coincidence between sea-level highstand chronologies in northeastern Brazil and those in the Bahamas and Bermuda.

Keywords : luinescence dating; northeastern razil; Pleistocene; sea-level change.