Carbonate Spikes and Displaced Components at Deep Sea Drilling Project Site 515: Pliocene/Pleistocene Depositional Processes in the Southern Brazil Basin

Abstract

Late Pliocene to Recent sediments from the southern Brazil Basin (DSDP Hole 515A, hydraulic piston core) were analyzed for evidence of episodic flow of Antarctic Bottom Water (AABW) through the Vema Channel. Carbonate-enriched layers punctuate the post-Pliocene section, otherwise composed predominantly of terrigenous silt and clay. Carbonate enrichment is thought to result from rapid deposition of fine-grained calcareous turbidites, originating in canyons incised on the northern margin of the Rio Grande Rise. The composition of benthic foraminiferal assemblages and the presence of stratigraphically displaced discoasters is consistent with a turbidite origin. Based on the presence of displaced Antarctic diatoms, AABW flow through the Vema Channel apparently has had a major influence on this site for only four periods during the last 2.7 Ma (about 45 to 250; 375 to 430; 700 to 780; 1320 to 1345 thousand yr. ago).

Sea-surface temperature reconstruction of the Quaternary western South Atlantic: New planktonic foraminiferal correlation function

“…Location map of core GeoB2806-4 within the western South Atlantic. (Johnson et al, 1982;Shor et al, 1982;Bickert and Wefer, 1996) and within the Brazil-Malvinas Confluence zone ( Fig. 1; Arhan et al, 2002Arhan et al, , 2003.…”