Abstract
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 differents ampling 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).
Highlights
The northernmost part of the southern Brazilian margin is known as the São Paulo Bight, an arc-shaped embayment extending from 23◦S to 28◦S (Zembruscki 1979)
In order to develop a better comprehension of the sedimentary processes in the context of these data, the samples were divided into three different geomorphological sectors, i.e., “Coast”, comprising the submerged coastal environments up to the 20-meter isobath; “Inner and Middle Shelf”, comprising the samples located from the 20-meter to the 100-meter isobath; and “Outer Shelf/Upper Slope”, beyond the 100-meter isobath
Most of the datings showed Mid- to Late Holocene ages with the exception of the base of one core (SS1), which showed a coherent sequence of datings with conventional radiocarbon ages ranging from ca. 39,300 yr BP to 10,240 yr BP
Summary
The northernmost part of the southern Brazilian margin is known as the São Paulo Bight, an arc-shaped embayment extending from 23◦S to 28◦S (Zembruscki 1979). A series of papers has reevaluated the sedimentary processes on the continental shelf and upper slope in terms of hydrodynamic factors and the input of terrigenous sediments. The latter is especially related to the transport of the Río de La Plata sediments to the Brazilian margin (Mahiques et al 2004, 2008, Campos et al 2008). The area has a big potential for studying changes related to the Last Climatic Cycle, sub-Milankovitch variations such as latitudinal shifts of the Intertropical Convergence Zone (ITCZ) (Haug et al 2001), and variations in the El Niño Southern Oscillation (ENSO) (Woodroffe et al 2003)
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