Pliocene-Holocene Polar Front Zone in the South Atlantic: changes in its position and sediment-accumulation rates from Holes 699A, 701C, and 704B

Abstract

The Pliocene-Holocene sediments recovered on ODP Leg 114 from Holes 699A, 701C, and 704B are the subject of a detailed investigation to interpret changes in the oceanographic environment of the South Atlantic in the vicinity of the Polar Front Zone (PFZ). The cores sample sediments at shallow (Hole 704B, 2532 m), intermediate (Hole 699A, 3716 m), and basinal (Hole 701C, 4647 m) depths. Sites 699 and 704 come under the influence of the Antarctic Circumpolar Current (ACC) and Circumpolar Deep Water. It is possible that the upper reaches of Antarctic Bottom Water (AABW) may also affect Hole 699A. Site 701 is influenced by AABW. Sharp fluctuations of large amplitude and high frequency in the lithology of the sediments from Hole 704B in the eastern South Atlantic, starting at about 0.75 my and characterizing the whole Brunhes Epoch, record the rapid movement of the northern border of the PFZ over the site. These reflect strong glacial/interglacial alternations in climate. To a lesser extent, lithologic fluctuations in Hole 701C reflect the same phenomenon, whereas in Hole 699A the lithology does not vary as dramatically. -from Authors