Quartz OSL sensitivity as a proxy for storm activity on the southern Brazilian coast during the Late Holocene

Autor(es)

Sawakuchi, A. O. ^[1] ; Guedes, C. C. F. ^[1] ; DeWitt, R. ^[2] ; Giannini, P. C. F. ^[1] ; Blair, M. W. ^[3] ; Nascimento, Jr., D. R. ^{[1, 4]} ; Faleiros, F. M. ^[5]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Geociencias, Dept Geol Sedimentar & Ambiental, BR-05508080 Sao Paulo - Brazil

^[2] E Carolina Univ, Dept Phys, Greenville, NC 27858 - USA

^[3] Los Alamos Natl Lab, Mat & Technol Div, Los Alamos, NM - USA

^[4] Univ Fed Ceara, Dept Geol, Ctr Ciencias, BR-60455760 Fortaleza, CE - Brazil

^[5] CPRM, Serv Geol Brasil, BR-01304010 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: QUATERNARY GEOCHRONOLOGY; v. 13, p. 92-102, DEC 2012.
• Citações Web of Science: 13

Resumo

Natural cycles of irradiation during burial and bleaching due to solar exposure during transport increase the Optically Stimulated Luminescence (OSL) sensitivity of quartz sand grains. The relationship between the OSL sensitivity and sediment transport allows to discriminate quartz sand grains with different depositional histories. In this paper, we evaluate the variation of OSL sensitivity in quartz grains deposited during the progradation of the Ilha Comprida barrier on the southern Brazilian, coast. Changes in sand sensitivity recorded by barrier growth since 6 ka ago are controlled by the variation in the proportion of low versus high sensitivity quartz grains. Low sensitivity grains with short sedimentary history are supplied by the Ribeira de Iguape River and reach the barrier through southward alongshore currents during fair weather conditions. Storm conditions shift the alongshore currents to northeast and permit the transport of high sensitivity grains with long sedimentary history from distal southern coastal sectors to the barrier. Therefore, the input of distal sediments for the Ilha Comprida barrier depends on the frequency and intensity of storms. Thus, the OSL sensitivity can be used as proxy for storm activity. The variation of OSL sensitivity through time indicates that the Ilha Comprida barrier changed from a relatively stable to an unstable storm pattern around 2 ka ago. Periods with increased storm activity peaked around AD 500, AD 1500 and AD 1850, approximately on the boundaries of the Medieval Climate Anomaly and the Little Ice Age. (C) 2012 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 07/54889-8 - Proveniencia sedimentar de graos de quartzo: comparacao de assinaturas tl e osl com dados termobarometricos e assembleias de minerais pesados.
• Beneficiário: André Oliveira Sawakuchi
• Modalidade de apoio: Auxílio à Pesquisa - Regular