Swath bathymetry and seismic reflection profiles collected by the Italian Antarctic Program (PNRA WEGA and MOGAM projects), combined with Australian (CSIRO) oceanographic measures (Williams et al., 2010) and benthic fauna sampling (Post et al., 2010), in the offshore of the George Vth Land, document evidence of bottom water cascading currents and turbidity currents inside continental slope canyons. The continental slope is incised by canyons heading to shelf edge sills and bounding sedimentary ridges of Miocene age. Dense shelf water forms in coastal polynya and is exported off the shelf break to form the Adélie Land branch of the Antarctic Bottom Water (ALBW, Rintoul et al., 2008). This bottom water is detected by CTD and mooring measurements up to about 3200m of depth, in the Jussieu canyon and further to the west. The speed of the ALBW is enough to transport fine sand and silt from shallow to deep water as documented by sea bed sediments. Similar bottom currents activity is recorded also during Quaternary glacial and interglacials (Caburlotto et al., 2009, Macrì et al., 2005) with source in the George V Land rocks and in the continental shelf (Damiani et al., 2006). The meandering charater of the Jussieu canyon and the sediment wave field on its eastern ridge, would suggest that they likely formed under the action of downslope, continous, bottom current, since the early Pliocene (Escutia et al., 2010). Caburlotto A., Lucchi R.G., De Santis L., Macrì P., Tolotti R. 2010. Sedimentary processes on the Wilkes Land continental rise reflect changes in glacial dynamic and bottom water flow. International Journal of Earth Sciences, 99(4), 909-926. Damiani D., Giorgetti G., Memmi Turbanti I. 2006. Clay mineral fluctuations and surface textural analysis of quartz grains in Pliocene–Quaternary marine sediments from Wilkes Land continental rise (East-Antarctica): Paleoenvironmental significance. Marine Geology, 226,81-295. Escutia C., Brinkhuis H., Klaus A. & Expedition 318 Scientists 2011. Proc. Intergrated Ocean Drilling Program, 318. Macrì P., Sagnotti L., Dinares-Turrel J., Caburlotto A. 2005. A composite record of Late Pleistocene relative geomagnetic paleointensity from the Wilkes Land Basin (Antarctica). Physics of the Earth and Planetary interiors, 151, 223-242. Post A.L., O’Brien P.E., Beaman R.J., Riddle M.J., De Santis L. 2010. Physical controls on deep water coral communities on the George v Land slope, East Antarctica 2010. Antarctic Science, 22 (4), 371-378. Rintoul S.R. 1998. On the origin and influence of Adelie Land bottom water. In: Ocean, Ice and Atmosphere: Interactions at the Antarctic Continental Margin. American Geophysical Union, Washington DC, 151-171.

Antarctic Bottom Water flow pathway inferred from geomorphology and seismic stratigraphy of the George V Land margin.

COLIZZA, ESTER;CANDONI, OLIVIERO;
2014

Abstract

Swath bathymetry and seismic reflection profiles collected by the Italian Antarctic Program (PNRA WEGA and MOGAM projects), combined with Australian (CSIRO) oceanographic measures (Williams et al., 2010) and benthic fauna sampling (Post et al., 2010), in the offshore of the George Vth Land, document evidence of bottom water cascading currents and turbidity currents inside continental slope canyons. The continental slope is incised by canyons heading to shelf edge sills and bounding sedimentary ridges of Miocene age. Dense shelf water forms in coastal polynya and is exported off the shelf break to form the Adélie Land branch of the Antarctic Bottom Water (ALBW, Rintoul et al., 2008). This bottom water is detected by CTD and mooring measurements up to about 3200m of depth, in the Jussieu canyon and further to the west. The speed of the ALBW is enough to transport fine sand and silt from shallow to deep water as documented by sea bed sediments. Similar bottom currents activity is recorded also during Quaternary glacial and interglacials (Caburlotto et al., 2009, Macrì et al., 2005) with source in the George V Land rocks and in the continental shelf (Damiani et al., 2006). The meandering charater of the Jussieu canyon and the sediment wave field on its eastern ridge, would suggest that they likely formed under the action of downslope, continous, bottom current, since the early Pliocene (Escutia et al., 2010). Caburlotto A., Lucchi R.G., De Santis L., Macrì P., Tolotti R. 2010. Sedimentary processes on the Wilkes Land continental rise reflect changes in glacial dynamic and bottom water flow. International Journal of Earth Sciences, 99(4), 909-926. Damiani D., Giorgetti G., Memmi Turbanti I. 2006. Clay mineral fluctuations and surface textural analysis of quartz grains in Pliocene–Quaternary marine sediments from Wilkes Land continental rise (East-Antarctica): Paleoenvironmental significance. Marine Geology, 226,81-295. Escutia C., Brinkhuis H., Klaus A. & Expedition 318 Scientists 2011. Proc. Intergrated Ocean Drilling Program, 318. Macrì P., Sagnotti L., Dinares-Turrel J., Caburlotto A. 2005. A composite record of Late Pleistocene relative geomagnetic paleointensity from the Wilkes Land Basin (Antarctica). Physics of the Earth and Planetary interiors, 151, 223-242. Post A.L., O’Brien P.E., Beaman R.J., Riddle M.J., De Santis L. 2010. Physical controls on deep water coral communities on the George v Land slope, East Antarctica 2010. Antarctic Science, 22 (4), 371-378. Rintoul S.R. 1998. On the origin and influence of Adelie Land bottom water. In: Ocean, Ice and Atmosphere: Interactions at the Antarctic Continental Margin. American Geophysical Union, Washington DC, 151-171.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11368/2836277
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