S to 22o S the Southern Brazilian shelf constitutes the only part of the Brazilian shelf with a subtropical to temperate environment. The studies on the different geological aspects of the area began in the 1960´s and have recently been reassessed after studies related to the determination of the Economic Exclusive Zone. In terms of morphology, the Southern Brazilian shelf may be divided into three sectors, the São Paulo Bight, the Florianópolis-Mostardas Sector and the Rio Grande Cone, characterized by conspicuous differences in terms of geological determining factors, bathymetry, declivities and the presence of canyons and channels. Despite the existence of hundreds of radiocarbon datings the sea level changes curve of southern Brazil during the Last Glacial Cycle is still a matter of debate. A recent controversy on the Middle and late Holocene sea level changes curve raised the question of the amplitude of the oscillations which occurred in the period. Also, a few but relatively consistent radiocarbon datings suggest the occurrence of a high sea level during Isotope Stage 3. In terms of sedimentary cover the Southern Brazilian shelf exhibits a very strong hydrodynamic control, both latitudinal and bathymetrical. The sector southward from 25 o S is characterized by the influence of the plume of water carrying sediments originating from the Río de La Plata. Actually its presence is conspicuous up to 28 o S, with the area between this latitude and 25 o S constituting a transitional zone. In terms of bathymetry the outer shelf is marked by the "floor-polisher" effect of the Brazil Current, which is responsible for the maintenance of a relict facies in areas deeper than 100 meters. R E S U M OEstendendo-se entre as latitudes 34 o S e 22 o S, a plataforma continental sul-brasileira constitui o único setor que corresponde a um ambiente subtropical a temperado. Os estudos dos diferentes aspectos geológicos da área iniciaram-se na década de 1960 e foram recentemente retomados após os trabalhos relativos à delimitação da Zona Econômica Exclusiva. Em termos de morfologia, pode ser dividida em três setores: Embaiamento de São Paulo, Setor Florianópolis-Mostardas e o Cone do Rio Grande, cada qual definido com base em diferenças geológicas relativas a batimetria, declividade e a presença de cânions e canais. A despeito da existência de centenas de datações ao radiocarbono, a curva de variações relativas do nível do mar no Último Ciclo Glacial é ainda tema de debate. Controvérsia recente sobre as curvas de variação do nível do mar sobre as durante o Holoceno Médio e Tardio trouxe à tona a questão da amplitude das oscilações do nível do mar. Adicionalmente, poucas mas consistentes datações sugerem a ocorrência de um nível do mar elevado durante o Estágio Isotópico 3. Em termos de processos sedimentares atuais, a plataforma continental sul-brasileira exibe um controle hidrodinâmico muito forte, tanto latitudinal quanto batimétrico. O setor ao sul de 25 o S é caracterizado pela influência da pluma de água que carreia sedimento...

The aim of this work was to generate an inventory of the data on radiocarbon datings obtained from sediments of the São Paulo Bight (southern Brazilian upper margin) and to analyze the data in terms of Late Quaternary sedimentary processes and sedimentation rates. A total of 238 radiocarbon datings from materials collected using different sampling procedures was considered for this work. The sedimentation rates varied from less than 2 to 68 cm.kyr -1 . The highest sedimentation rate values were found in a low-energy (ría type) coastal system as well as in the upwelling zones of Santa Catarina and Cabo Frio. The lowest rates were found on the outer shelf and upper slopes. Our results confirm the strong dependency of the shelf currents, with an emphasis to the terrigenous input from the Río de La Plata outflow which is transported via the Brazilian Coastal Current, as well as of the coupled Brazil Current -Intermediate Western Boundary Current (BC-IWBC) dynamics on the sedimentary processes. At least three indicators of the paleo sea level were found at 12200 yr BP (conventional radiocarbon age) (103 meters below sea level -mbsl), 8300-8800 cal yr BP (13 mbsl) and 7700-8100 cal yr BP (6 mbsl).

A B S T R A C TSediment cores are an essential tool for the analysis of the dynamics of mangrove succession. Coring was used to correlate changes in depositional environments and lateral sedimentary facies with discrete stages of forest succession at the Cananéia-Iguape Coastal System in southeastern Brazil. A local level successional pattern was examined based on four core series T1) a sediment bank; T2) a smooth cordgrass Spartina alterniflora bank; T3) an active mangrove progradation fringe dominated by Laguncularia racemosa, and; T4) a mature mangrove forest dominated by Avicennia schaueriana. Cores were macroscopically described in terms of color, texture, sedimentary structure and organic components. The base of all cores exhibited a similar pattern suggesting common vertical progressive changes in depositional conditions and subsequent successional colonization pattern throughout the forest. The progradation zone is an exposed bank, colonized by S. alterniflora. L. racemosa, replaces S. alterniflora as progradation takes place. As the substrate consolidates A. schaueriana replaces L. racemosa and attains the greatest structural development in the mature forest. Cores collected within the A. schaueriana dominated stand contained S. alterniflora fragments near the base, confirming that a smooth cordgrass habitat characterized the establishment and early seral stages. Cores provide a reliable approach to describe local-level successional sequences in dynamic settings subject to drivers operating on multiple temporal and spatial scales where spatial heterogeneity can lead to multiple equilibria and where similar successional end-points may be reached through convergent paths. RESUMOTestemunhos de sondagem apresentam-se como importantes ferramentas para análise da dinâmica sucessional de bosques de mangue. A sucessão dos bosques de mangue, no litoral sul do Estado de São Paulo (Brasil), foi determinada com base em quatro testemunhos de sondagem: T1) banco de sedimento; T2) banco de gramínea Spartina alterniflora; T3) bosque de mangue em progradação, dominado por Laguncularia racemosa; e T4) bosque de mangue maduro, dominado por Avicennia schaueriana. Os testemunhos foram descritos macroscopicamente em função de cor, textura, estruturas sedimentares e componentes orgânicos. A base de todos os testemunhos apresentou padrão semelhante, sugerindo colonização similar por bosques de mangue , em toda sua extensão. Áreas em progradação apresentam banco de sedimento exposto, colonizado por S. alterniflora. Faixa de L. racemosa substitui a gramínea, com a progradação. À maior consolidação do sedimento, passam a dominar outras espécies típicas de mangue, como observado no bosque maduro, onde A. schaueriana alcança grande desenvolvimento estrutural. No testemunho coletado na área colonizada pelo bosque maduro dominado por A. shaueriana, há fragmentos de S. alterniflora próximo à base, confirmando o papel da gramínea como espécie pioneira. Os testemunhos analisados refletem a zonação e a sucessão dos bosques de mangue da r...