The Ioffe Drift

Book excerpt: The Discovery of the calcareous Ioffe Drift in the SW Atlantic in 2010 opens new perspectives in the contourite theory. Although demonstrating similar behavior relative to bottom water dynamics, rather rare and poorly studied calcareous contourites differ from their terrigenous analogs in origin, grain-size distribution, chemical and mineral composition of sedimentary particles. The detailed multidisciplinary study of the Ioffe Drift produces new knowledge on biogenic contourites deposited in pelagic realm, in conditions of low biological productivity and terrigenous material supply, under the influence of the Antarctic Bottom Water flow from the Vema Channel. The major intervals of prevailing erosion are inferred on the drift from 2.51/2.59 to 1.9 Ma and from 1.6 to 0.81 Ma thus indicating strong paleoceanographic changes most likely associated with the reorganization of deep-sea circulation and increased bottom water production in the Southern Ocean during the Early Pleistocene and, in particular, around the Mid-Pleistocene Transition.