info:eu-repo/semantics/article
SEDIMENTAÇÃO RECENTE NA COSTA ATLÂNTICA DE SALVADOR
SEDIMENTAÇÃO RECENTE NA COSTA ATLÂNTICA DE SALVADOR
Autor
BITTENCOURT, ABÍLIO CARLOS DA SILVA PINTO
Institución
Resumen
Wave energy and the proximity of granulite outcrops or river mouths appear to be the three principal factors controlling the composition and texture of the sand in the atlantic litoral of Salvador, State of Bahia, Brazil. The sand is chiefly quartzose with contributions of biogenic carbonate grains (maximum 58%, minimum 6%). Samples collected on the beach near granulite outcrops have a feldspar content up to 3.5%, sub-angular grains, medium to coarse median-diameters, a positive skewness and characteristics of transport by roIling. Samples taken distant from outcrops show sub-rounded grains, medium to fine median-diameters, a positive or negative skewness depending on the proximity or absence, respectively, of river mouths, and have been transported in graded suspension with or without additional rolling. High energy beaches have the lowest content of bioclasts and, where rock outcrops are absent, exhibit a symmetrical distribution or negative skewness. The best sorting values correspond to medium sand. The degree of roundness grows with the sphericity and with particle size. Wave energy and the proximity of granulite outcrops or river mouths appear to be the three principal factors controlling the composition and texture of the sand in the atlantic litoral of Salvador, State of Bahia, Brazil. The sand is chiefly quartzose with contributions of biogenic carbonate grains (maximum 58%, minimum 6%). Samples collected on the beach near granulite outcrops have a feldspar content up to 3.5%, sub-angular grains, medium to coarse median-diameters, a positive skewness and characteristics of transport by roIling. Samples taken distant from outcrops show sub-rounded grains, medium to fine median-diameters, a positive or negative skewness depending on the proximity or absence, respectively, of river mouths, and have been transported in graded suspension with or without additional rolling. High energy beaches have the lowest content of bioclasts and, where rock outcrops are absent, exhibit a symmetrical distribution or negative skewness. The best sorting values correspond to medium sand. The degree of roundness grows with the sphericity and with particle size.