Beach ridges, foredunes or transgressive dunefields? Definitions and an examination of the Torres to Tramandaí barrier system, Southern Brazil

Anais da Academia Brasileira de Ciências

Patrick A. Hesp²  Sergio R. Dillenburg¹  Eduardo G. Barboza¹  Luiz J. Tomazelli¹  Ricardo N. Ayup-zouain¹  Luciana S. Esteves¹  Nelson L.s. Gruber¹  Elirio E. Toldo-jr.¹  Luiz L.c. De A. Tabajara¹  Luiz C.p. Clerot¹ 

[1] ,Louisiana State University Department of Geography and Anthropology Baton Rouge LA ,USA

关键词: beach ridges;    coastal barriers;    transgressive dunefields;    Holocene;    southern Brazil;    cordões de praia;    barreiras costeiras;    dunas transgressivas;    Holoceno;    sul do Brasil;   

DOI  :  10.1590/S0001-37652005000300010

来源: SciELO

【 摘 要 】

Many prograded barriers and some dunefields in theworld have been termed 'beach ridge' plains, but the actual genesis of the 'ridges' is often unknown. Use of the terms, berms, beach ridges and foredunes is also confusing in the literature because their definitions are highly variable and are commonly used interchangeably. Thus, the formation and definition of sand berms, beach ridges and foredunes is briefly reviewed. Beach ridges are re-defined as entirely wave formed deposits which are most commonly formed during high wave conditions and/or elevated water levels (e.g. storm surges). Foredunes are formed by aeolian sand deposition in vegetation on the backshore. Some dunefields in Brazil have been called beach ridge plains when they are, in fact, foredune plains, transgressive dunefields, or complex barriers (i.e. barriers comprising two types of dunes). The Holocene barrier extending from Torres to Tramandaí in southern Brazil has been regarded as a beach ridge plain. The landforms of this Holocene barrier comprise wide, relatively linear, widely spaced (400-600m), shore parallel ridges on the landward half, and more closely spaced (80-400m), lobate and crescentic, discrete ridges on the seaward half. Low, rolling dunefields, sand sheets, nebkha fields and deflation plains occur between the ridges. The barrier is re-interpreted as a prograded, transgressive dunefield barrier.

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