Distribui？？o sedimentar da Lagoa Rodrigo de Freitas através de sísmica de alta resolu？？o

the rodrigo de freitas lagoon (rio de janeiro state) sediments and bottom characteristics were analyzed using high-resolution (10 khz) sub-bottom profiles associated with particle size analyses of 44 bottom sediment samples. four types of echo-characters were identified revealing the strong relation with the particle size distribution and bottom morphology. in areas of acoustic penetration, the basement delineates buried sugar-loaf hills and infilled-valley features. the total sediment thickness can reach as much as 16 meters along the paleovalleys, which are aligned in a ne-sw direction, parallel to the regional basement orientation observed on the coastal massifs. there is a predominance of organic rich muddy sediments, infilling the paleovalleys which are the main sites of shallow gas occurrences within the lagoonal sediments.