Neogene ice-rafted debris record of ODP Hole 120-751A

One of the primary objectives of Leg 120 was to obtain a high-resolution Neogene stratigraphic section from the Kerguelen Plateau. Site 751, located in the central part of the Raggatt Basin on the Southern Kerguelen Plateau in 1633.8 m of water (57°43.56'S; 79°48.89'E), was selected as the dedicated Neogene site for this objective. High-resolution sampling at Site 751 was used to delineate in detail the Neogene ice-rafted debris (IRD) occurrences on the Kerguelen Plateau. The oldest IRD found at Site 751 was approximately 9.9 Ma, and it was not until approximately 8.5 Ma that significant concentrations of IRD were detected. The first major IRD event at this site occurred in the uppermost Miocene between 6.0 and 5.5 Ma. During this time period, a general climatic cooling and glacial expansion occurred on Antarctica. The late Miocene IRD event was followed by a continuous episode of elevated IRD deposition in the lowermost Pliocene between 4.5 and 4.1 Ma. The 0.4-m.y. duration and the timing of the early Pliocene IRD event on the Kerguelen Plateau corresponds with IRD fluxes observed on the Falkland Plateau and in the Weddell Abyssal Plain. This correspondence of data indicates that a major global climatic event occurred during the early Pliocene. The East Antarctic Ice Sheet may have experienced deglaciation between 4.5 and 4.1 Ma and, as a result, released large volumes of sediment-laden ice into the Southern Ocean

Distribution of clay minerals in ODP Hole 120-751A (Table 1)

The purpose of this paper is to present data from a clay mineralogy investigation of the sediments analyzed for ice-rafted debris (IRD) from Hole 751A (see Breza, 1992, doi:10.2973/odp.proc.sr.120.136.1992). This data is significant in that the change in clay mineralogy may provide information about the Neogene evolution of climate and oceanic circulation near the Kerguelen Plateau and adjacent to Prydz Bay, Antarctica. Site 751 is located in the central part of the Raggatt Basin on the Southern Kerguelen Plateau in 1633.8 m of water (57°43.56'S, 79°48.89'E). The plateau is a structural high isolated from any continental input by means of turbidities or nepheloid transport. It is bounded to the northeast by the Australian-Antarctic Basin, to the southwest by the African-Antarctic Basin, and to the northwest by the Crozet Basin. To the south it is separated from Antarctica by the Princess Elizabeth Trough. Site 751 consists of two lithologic units. Unit I is composed of 40 m of upper Pleistocene to lower Pliocene diatom ooze with varying amounts of IRD and foraminifers. Unit II consists of 126 m of upper to lower Miocene diatom nannofossil ooze, with nannofossils as the primary sedimentary component