The interaction between biogenic silica export and burial, paleoceanography, diatom species succession and mats formation was examined based on relative abundances data of Plio/Pleistocene diatoms from six cores recovered during ODP Leg 177 on a transect across the Antarctic Circumpolar Current (ACC) in the Atlantic sector of the Southern Ocean. Fragilariopsis kerguelensis, Actinocyclus ingens and species of the genus Thalassiothrix were the main contributors to the diatom assemblages.Three main steps marked the development of the silica system in the Southern Ocean:Step 1 (at ca. 2.77 Ma), establishment of increased biogenic silica burial in the Antarctic Circumpolar Current area, following the large-scale oceanic reorganization connected to the increased northern hemisphere glaciation;Step 2 (at ca. 1.93 Ma), the Antarctic Polar Front becomes the main biogenic silica sink, diatom mats are widespread, and are also found slightly to the north and south of the APF;Step 3 (at ca. 0.63 Ma), with the strong drop in abundance (and later extinction at 0.38 Ma) of A. ingens and the rise to dominance of F. kerguelensis, the system enters a glacial-interglacial mode, with diatom mats occurring during interglacials at the APF and in the Antarctic Zone, but disappearing north of it.

Sediment depth is given in mcd. X = presence, - = absence of diatom mats. Diatom occurrence data see Zielinski and Gersonde (2003) datasets doi:10.1594/PANGAEA.678517. For age models see Zielinski and Gersonde (2002) datasets doi:10.1594/PANGAEA.678533. Data extracted in the frame of a joint ICSTI/PANGAEA IPY effort, see http://doi.pangaea.de/10.1594/PANGAEA.150150

Supplement to: Cortese, Giuseppe; Gersonde, Rainer (2008): Plio/Pleistocene changes in the main biogenic silica carrier in the Southern Ocean, Atlantic Sector. Marine Geology, 252(3-4), 100-110