The sediments of Gunnerus Ridge and Kainan Maru Seamount (Indian sector of Southern Ocean)

Combined bathymetric, sediment echosounding and sediment coring data from two expeditions of the RV “Polarstern” (ANT-VIII/6, ANT-XI/4) provides the first more comprehensive overview of Cenozoic sedimentation in the remote area of the Gunnerus Ridge and Kainan Maru Seamount off the Antarctic Continent (Indian sector of Southern Ocean). The Neogene and Oligocene sediment sequences were affected by at least three generations of large scale slide and slump events, which occurred around the early/late Pliocene and the early/late Oligocene boundaries and during an earlier time period in the Paleogene. Possible triggers for slumping events might have been changes in the circulation pattern, changes in sea level, or earthquakes. Changes in water mass circulation could have affected the distribution of sediments since the onset of the Neogene in conjunction with the establishment of the Antarctic Circumpolar Current (ACC). The recovered sediments are predominantly biosiliceous mud and ooze, except for early Oligocene and Quaternary sequences, which contain calcareous nannofossils and foraminifera, respectively. The sediments have been deposited at low sedimentation rates ranging from a few millimeters to centimeters per 1000 yr.