HR: 10:20h
AN: C42A-01    [Abstracts]
TI: Chronostratigraphic constraints on Pliocene warmth and Pleistocene cooling in the ANDRILL-1B drillcore from beneath the McMurdo Ice Shelf, Antarctica.
AU: * Wilson, G S
EM: gary.wilson@otago.ac.nz
AF: Department of Geology University of Otago, PO Box 56, Dunedin, 9054, New Zealand
AU: Naish, T R
AF: GNS Science, PO Box 30368, Lower Hutt, 5040, New Zealand
AU: Naish, T R
AF: Antarctic Research Centre Victoria University of Wellington, PO Box 600, Wellington, 6140, New Zealand
AU: Powell, R D
AF: Department of Geology and Environmental Geosciences Northern Illinois University, 312 Davis Hall Normal Road, DeKalb, IL 60115-2854, United States
AU: Levy, R H
AF: ANDRILL Science Management Office University of Nebraska - Lincoln, 126 Bessey Hall, Lincoln, NE 68588-0340, United States
AU: Winter, D M
AF: Department of Geosciences University of Nebraska - Lincoln, 214 Bessey Hall, Lincoln, NE 68588-0340, United States
AU: Browne, G
AF: GNS Science, PO Box 30368, Lower Hutt, 5040, New Zealand
AU: Dunbar, N
AF: Earth and Environmental Science Department New Mexico Institute of Technology, 801 Leroy Place, Socorro, NM 87801, United States
AU: Florindo, F
AF: Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata, 6075, Rome, I-00143, Italy
AU: Graham, I
AF: GNS Science, PO Box 30368, Lower Hutt, 5040, New Zealand
AU: Henrys, S A
AF: GNS Science, PO Box 30368, Lower Hutt, 5040, New Zealand
AU: McIntosh, W C
AF: Earth and Environmental Science Department New Mexico Institute of Technology, 801 Leroy Place, Socorro, NM 87801, United States
AU: McKay, R M
AF: Antarctic Research Centre Victoria University of Wellington, PO Box 600, Wellington, 6140, New Zealand
AU: Ohneiser, C
AF: Department of Geology University of Otago, PO Box 56, Dunedin, 9054, New Zealand
AU: Ross, J I
AF: Earth and Environmental Science Department New Mexico Institute of Technology, 801 Leroy Place, Socorro, NM 87801, United States
AU: Sagnotti, L
AF: Earth and Environmental Science Department New Mexico Institute of Technology, 801 Leroy Place, Socorro, NM 87801, United States
AU: Scherer, R P
AF: Department of Geology and Environmental Geosciences Northern Illinois University, 312 Davis Hall Normal Road, DeKalb, IL 60115-2854, United States
AU: Sjunneskog, C
AF: Department of Geology and Geophysics Louisiana State University, Howe-Russell Geoscience Complex, Baton Rouge, LA 70803, United States
AU: Strong, C P
AF: GNS Science, PO Box 30368, Lower Hutt, 5040, New Zealand
AU: Taviani, M
AF: ISMAR-CNR, Via Gobetti 101, Bologna, 40129, Italy
AU: MIS Project Science Team, A
AF: http://www.andrill.org/support/references/appendixc.html, ANDRILL Science Management Office University of Nebraska - Lincoln 126 Bessey Hall, Lincoln, NE 68588-0340, United States
AB: In the 2006/2007 Austral summer, the ANDRILL project recovered a 1,285m Neogene drillcore (AND-1B) from the Victoria Land Basin beneath the McMurdo Ice Shelf (78°S), SW Ross Sea, Antarctica. Chronostratigraphic data available for the upper 700 m of the drillcore include diatom biostratigraphy, magnetostratigraphy, ⁴⁰Ar/³⁹Ar ages, ⁸⁷Sr/⁸⁶Sr ages and surfaces of erosion identified from physical appearance in the drillcore. The age data allow a relatively well-constrained age model to be constructed and allow direct correlation with the Geomagnetic Polarity Time Scale for ~70% of the upper 700m of the AND-1B record. The age model for the upper 700m of the drillcore indicates relatively rapid (up to 1m/k.y.) accumulation punctuated by several half to million year hiatuses representing more than half of the last 7 m.y. The Pliocene interval of the core is represented by ~450m of alternating diatomaceous and glacimarine strata comprising ~250m of Early Pliocene diatomaceous strata deposited relatively continuously between 4.9 and 4.2 Ma overlain by a more punctuated ~200m record of alternating diatomaceous and glacimarine strata deposited in the Late Pliocene (2.4-3.3 m.y.). The age model identifies several Late Pliocene 0.5-1 m.y. hiatuses in the AND-1B record coincident with glacial advance, grounding and erosion across the Western Ross Sea floor identified as glacial surfaces of erosion in the AND-1B drillcore and correlative with major regional unconformities in the seismic stratigraphic record of the Victoria Land Basin. Magnetic polarity tie points suggest that these hiatuses coincide with major Late Pliocene glacial isotope excursions with orbital-scale glacial variability recognised between major hiatuses. The upper ~150m of the AND-1B record includes a more strongly glacimarine succession which is dominated by diamicts, which indicate glacial advance and grounding in the western Ross Sea. Magnetic polarity stratigraphy and ⁴⁰Ar/³⁹Ar ages on volcanics between 100m and 150m indicate that orbital scale variability is still present in the Pleistocene record.
DE: 0700 CRYOSPHERE (4540)
DE: 0728 Ice shelves
DE: 1520 Magnetostratigraphy
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1641 Sea level change (1222, 1225, 4556)
SC: Cryosphere [C]
MN: 2007 Fall Meeting