HR: 10:35h
AN: C42A-02    [Abstracts]
TI: A Paleobathymetry Modelling Of The Ross Sea
AU: * De Santis, L
EM: ldesantis@ogs.trieste.it
AF: Istituto Nazionale di Oceanografia e di Geofisica Sperimentale - OGS, Borgo Grotta Gigante 42/c, Trieste, 34010, Italy
AU: Prato, S
EM: prato@area.trieste.it
AF: A.P.E. Research, Area Science Park Basovizza, s.s. 14, Km 163,5, Trieste, 34012, Italy
AB: Today the continental shelf of the Ross Sea is overdeepened (more than 500 m) and is characterised by glacial valleys incised by multiple advances of ice streams, draining both the East Antarctic Ice Sheet (EAIS) and the West Antarctic Ice Sheet (WAIS). Post-rift backstripping modelling has been applied to depth contour maps of some principal unconformities, previously compiled in the frame of the ANTOSTRAT project (Cooper, Barker, Brancolini, 1995), in order to reconstruct the Ross Sea paleobathymetry through its Cenozoic evolution The depth contour maps have been restored after removing sediment load, assuming Airy isostatic compensation, and including constraints from DSDP site 270. The restored maps show the diachronous formation of glacial troughs and banks, in relation with the development of the Eastern and Western Ice Sheets. Major changes in the shape of the continental shelf and slope throughout the Cenozoic can be recognised: Until the late Oligocene the continental shelf was characterised by terrestrial areas (e.g. the Central high) outcropping above sea level and hosting valley glaciers or small ice caps. A continental shelf edge was not clearly developed yet, the eastern flank of the Central High appeared as an inclined ramp, dipping toward the ocean In the early Miocene glacial processes shaped the shallow sectors of the continental shelf, where small ice caps likely developed. Marine processes influenced the deposition in the deepest areas of the Eastern Basin, where no evidences of erosion and deposition from ice streams are found. The shelf profile was seaward dipping and not overdeepened yet. The first evidence of ice stream incision across the shallowest central area of the continental shelf is found in the Mid-Miocene (?16.2-?14 Ma) sequences. The deep incision has SW-NE direction and may be caused by ice streams draining from the Eastern Antarctic Ice Sheet. Sub-glacial delta features have been preserved along the trough-axis up to the paleo-shelf edge, where a trough-mouth fan formed. In the late Miocene-early Pliocene (?10 - ?4 Ma) the bathymetric profile of the continental shelf progressively evolved from seaward to landward dipping in the Eastern Ross Sea and reached a generally overdeepened configuration, similar to the present day profile. Depositional and erosional processes over the continental shelf were largely controlled by ice streams dynamics. Cooper, A. K., Barker, P. F., Brancolini, G., (Eds.), Geology and seismic stratigraphy of the Antarctic margin, Antarct. Res. Ser., vol. 68, 301 pp., atlas, CD-ROMs, AGU, Washington, D.C.
DE: 0730 Ice streams
DE: 0774 Dynamics
DE: 0776 Glaciology (1621, 1827, 1863)
DE: 3022 Marine sediments: processes and transport
DE: 3025 Marine seismics (0935, 7294)
SC: Cryosphere [C]
MN: 2007 Fall Meeting