8. CLAY MINERAL STRATIGRAPHY OF THE RIO GRANDE RISE AND SOUTHERN BRAZIL BASIN, WESTERN SOUTH ATLANTIC OCEAN1

• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Core materials from the Deep Sea Drilling Project; Antarctic; Antarc*; South Atlantic Ocean
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.622.8874; http://www.deepseadrilling.org/72/volume/dsdp72_08.pdf

Clay mineral facies of DSDP Sites (Legs 39 and 72) in the western South Atlantic Ocean reflect the region's tectonic and paleoceanographic events. An abrupt change to a smectite-dominated assemblage occurs in the lower Tertiary and represents the onset of extensive volcanic activity at that time. In the Coniacian-Campanian section of Site 516, a well-crystallized kaolinite suggests the presence of a deeply weathered continental remnant at the crest of the Rio Grande Rise and strongly opposed current systems at shallow and mid-water depths on the northern flanks of the Rise. Within the Rio Grande Gap, initiation of Antarctic Bottom Water flow occurs within the time span represented by an early Eocene-Oligocene unconformity in the sediment section of Site 515 at the northern terminus of the Vema Channel.