Monday, 27 August 2007 - 4:20 PM
1.P2.A-3
Preliminary chronostratigraphy for the upper 700 m (upper Miocene – Pleistocene) of the AND-1B drillcore recovered from beneath the McMurdo Ice Shelf, Antarctica
Gary S. Wilson1, Richard H. Levy2, Greg Browne3, Fabio Florindo4, Stuart A. Henrys3, Ian Graham3, William C. McIntosh5, R. M. McKay6, T. R. Naish6, Christian Ohneiser1, Ross D. Powell7, Jake I. Ross5, Leonardo Sagnotti4, Reed Scherer7, Charlotte Sjunneskog8, C. Percy Strong3, Marco Taviani9, and Diane Winter10. (1) Department of Geology, University of Otago, PO Box 56, Dunedin, New Zealand, (2) ANDRILL Science Management Office, University of Nebraska - Lincoln, 126 Bessey Hall, Lincoln, NE 68588-0341, (3) GNS Science, 1 Fairway Drive, Avalon, Lower Hutt, New Zealand, (4) Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata, 605, Rome, I-00143, Italy, (5) Department of Earth and Environmental Sciences, New Mexico Tech, 801 Leroy Pl, Socorro, NM 87801, (6) Antarctic Research Centre, Victoria University of Wellington, Wellington, New Zealand, (7) Department of Geology and Environmental Geosciences, Northern Illinois University, DeKalb, IL 60115, (8) Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA 70803, (9) ISMAR-CNR, Via Gobetti 101, Bologna, Italy, (10) University of Nebraska - Lincoln, Department of Geosciences, Lincoln, NE 68588
Chronostratigraphic data available for the preliminary age model for the upper 700 m for the AND-1B drill core include diatom biostratigraphy, magnetostratigraphy, 40Ar/39Ar ages, 87Sr/86Sr ages nd surfaces of erosion identified from physical appearance in the drill core. The age data allow a relatively well-constrained age model to be constructed. ~70% of the AND-1B magnetic polarity stratigraphy can be correlated with the Geomagnetic Polarity Time Scale (GPTS). Unique correlation is not possible in several coarse diamictite intervals with closely spaced glacial surfaces of erosion and sparse microflora. However, the age model 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. in the drillcore. The mid-late Pleistocene is represented by superimposed diamictite units separated from late Pliocene alternating diamictites / diatomites by a ~ 1 m.y. hiatus.