15 research outputs found
Beach ridges, foredunes or transgressive dunefields? Definitions and an examination of the Torres to TramandaĂ barrier system, Southern Brazil
The role of population movement in the epidemiology and control of schistosomiasis in Brazil: a preliminary typology of population movement
Germination responses of the invasive Calotropis procera (Ait.) R. Br. (Apocynaceae): comparisons with seeds from two ecosystems in northeastern Brazil
Composition of functional ecological guilds of the fish fauna of the internal sector of the Amazon Estuary, ParĂĄ, Brazil
Child's anxiety preceding the dental appointment: evaluation through a playful tool as a conditioning feature
A reevaluation of the late quaternary sedimentation in todos os Santos Bay (BA), Brazil
Todos os Santos Bay is a large (<img ALIGN="BOTTOM" BORDER="0" SRC="http:/img/fbpe/aabc/v72n4/0052img1.gif" ALT=""> 1000 kmÂČ), structurally controlled tidal bay in northeast Brazil. Three main drainage basins debouch into the bay, providing a mean freshwater discharge of 200 mÂł/s (prior to 1985), or less than 1% of the spring tidal discharge through the bay mouth. Based on the result of several sedimentological studies performed in the 1970's, five surface sedimentary facies were identified inside the bay, namely i) transgressive siliciclastic marine sand facies; ii) transgressive bay sand-mud facies; iii) a transgressive carbonate marine sand facies; iv) regressive bay-mud facies, and v) regressive fluvial sand facies. The spatial distribution of these facies would follow, somewhat closely, the hydrodynamic-energy distribution inside the bay. Seismic profiles along the bay bottom indicate the existence of several paleochannels, 5-10 m deep, blanketed at least by three different sedimentary units. The topmost sedimentary unit, 5-20 m thick, appears to be associated with the regressive bay-mud facies, and assuming that it was laid down within the last 5000 years, sedimentation rates for the central and northeastern part of the bay would average at 2,4 mm/y