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Patterson, MO, McKay R, Naish T, Escutia C, Jimenez-Espejo FJ, Raymo ME, Meyers SR, Tauxe L, Brinkhuis H, Scientists IE318.  2014.  Orbital forcing of the East Antarctic ice sheet during the Pliocene and Early Pleistocene. Nature Geoscience. 7:841-847.   10.1038/ngeo2273   AbstractWebsite

The Pliocene and Early Pleistocene, between 5.3 and 0.8 million years ago, span a transition from a global climate state that was 2-3 degrees C warmer than present with limited ice sheets in the Northern Hemisphere to one that was characterized by continental-scale glaciations at both poles. Growth and decay of these ice sheets was paced by variations in the Earth's orbit around the Sun. However, the nature of the influence of orbital forcing on the ice sheets is unclear, particularly in light of the absence of a strong 20,000-year precession signal in geologic records of global ice volume and sea level. Here we present a record of the rate of accumulation of iceberg-rafted debris offshore from the East Antarctic ice sheet, adjacent to the Wilkes Subglacial Basin, between 4.3 and 2.2 million years ago. We infer that maximum iceberg debris accumulation is associated with the enhanced calving of icebergs during ice-sheet margin retreat. In the warmer part of the record, between 4.3 and 3.5 million years ago, spectral analyses show a dominant periodicity of about 40,000 years. Subsequently, the powers of the 100,000-year and 20,000-year signals strengthen. We suggest that, as the Southern Ocean cooled between 3.5 and 2.5 million years ago, the development of a perennial sea-ice field limited the oceanic forcing of the ice sheet. After this threshold was crossed, substantial retreat of the East Antarctic ice sheet occurred only during austral summer insolation maxima, as controlled by the precession cycle.

Cook, CP, van de Flierdt T, Williams T, Hemming SR, Iwai M, Kobayashi M, Jimenez-Espejo FJ, Escutia C, Gonzalez JJ, Khim BK, McKay RM, Passchier S, Bohaty SM, Riesselman CR, Tauxe L, Sugisaki S, Galindo AL, Patterson MO, Sangiorgi F, Pierce EL, Brinkhuis H, Scientists IE318.  2013.  Dynamic behaviour of the East Antarctic ice sheet during Pliocene warmth. Nature Geoscience. 6:765-769.   10.1038/ngeo1889   AbstractWebsite

Warm intervals within the Pliocene epoch (5.33-2.58 million years ago) were characterized by global temperatures comparable to those predicted for the end of this century(1) and atmospheric CO2 concentrations similar to today(2-4). Estimates for global sea level highstands during these times(5) imply possible retreat of the East Antarctic ice sheet, but ice-proximal evidence from the Antarctic margin is scarce. Here we present new data from Pliocene marine sediments recovered offshore of Adelie Land, East Antarctica, that reveal dynamic behaviour of the East Antarctic ice sheet in the vicinity of the low-lying Wilkes Subglacial Basin during times of past climatic warmth. Sedimentary sequences deposited between 5.3 and 3.3 million years ago indicate increases in Southern Ocean surface water productivity, associated with elevated circum-Antarctic temperatures. The geochemical provenance of detrital material deposited during these warm intervals suggests active erosion of continental bedrock from within the Wilkes Subglacial Basin, an area today buried beneath the East Antarctic ice sheet. We interpret this erosion to be associated with retreat of the ice sheet margin several hundreds of kilometres inland and conclude that the East Antarctic ice sheet was sensitive to climatic warmth during the Pliocene.

Tauxe, L, Stickley CE, Sugisaki S, Bijl PK, Bohaty SM, Brinkhuis H, Escutia C, Flores JA, Houben AJP, Iwai M, Jimenez-Espejo F, McKay R, Passchier S, Pross J, Riesselman CR, Rohl U, Sangiorgi F, Welsh K, Klaus A, Fehr A, Bendle JAP, Dunbar R, Gonzalez J, Hayden T, Katsuki K, Olney MP, Pekar SF, Shrivastava PK, van de Flierdt T, Williams T, Yamane M.  2012.  Chronostratigraphic framework for the IODP Expedition 318 cores from the Wilkes Land Margin: Constraints for paleoceanographic reconstruction. Paleoceanography. 27   10.1029/2012pa002308   AbstractWebsite

The Integrated Ocean Drilling Program Expedition 318 to the Wilkes Land margin of Antarctica recovered a sedimentary succession ranging in age from lower Eocene to the Holocene. Excellent stratigraphic control is key to understanding the timing of paleoceanographic events through critical climate intervals. Drill sites recovered the lower and middle Eocene, nearly the entire Oligocene, the Miocene from about 17 Ma, the entire Pliocene and much of the Pleistocene. The paleomagnetic properties are generally suitable for magnetostratigraphic interpretation, with well-behaved demagnetization diagrams, uniform distribution of declinations, and a clear separation into two inclination modes. Although the sequences were discontinuously recovered with many gaps due to coring, and there are hiatuses from sedimentary and tectonic processes, the magnetostratigraphic patterns are in general readily interpretable. Our interpretations are integrated with the diatom, radiolarian, calcareous nannofossils and dinoflagellate cyst (dinocyst) biostratigraphy. The magnetostratigraphy significantly improves the resolution of the chronostratigraphy, particularly in intervals with poor biostratigraphic control. However, Southern Ocean records with reliable magnetostratigraphies are notably scarce, and the data reported here provide an opportunity for improved calibration of the biostratigraphic records. In particular, we provide a rare magnetostratigraphic calibration for dinocyst biostratigraphy in the Paleogene and a substantially improved diatom calibration for the Pliocene. This paper presents the stratigraphic framework for future paleoceanographic proxy records which are being developed for the Wilkes Land margin cores. It further provides tight constraints on the duration of regional hiatuses inferred from seismic surveys of the region.