26 research outputs found
Postglacial sedimentary processes on the Storfjorden and Kveithola trough mouth fans: significance of extreme glacimarine sedimentation
18The depositional history of the Storfjorden and Kveithola trough-mouth fans (TMFs) in the
northwestern Barents Sea has been investigated within two coordinated Spanish and Italian projects in
the framework of the International Polar Year (IPY) Activity 367, NICE STREAMS. The investigation has
been conducted using a multidisciplinary approach to the study of sediment cores positioned on highresolution
multibeam bathymetry and TOPAS/CHIRP sub-bottom profiles.
Core correlation and the age model were based on 27 AMS 14C samples, rock magnetic parameters,
lithofacies sequences, and the presence of marker beds including two oxidized layers marking the post
Last Glacial Maximum (LGM) inception of deglaciation (OX-2) and the Younger Dryas cold climatic
event (OX-1).
Sediment facies analysis allowed the distinction of a number of depositional processes whose onset
appears closely related to ice stream dynamics and oceanographic patterns in response to climate
change. The glacigenic diamicton with low water content, high density, and high shear strength,
deposited during glacial maxima, indicates ice streams grounded at the shelf edge. Massive release of
IRD occurred at the inception of deglaciation in response to increased calving rates with possible outer
ice streams lift off and collapse. The presence of a several-meter-thick sequence of interlaminated
sediments deposited by subglacial outbursts of turbid meltwater (plumites) indicates rapid ice
streams' melting and retreat. Crudely-layered and heavily-bioturbated sediments were deposited by
contour currents under climatic/environmental conditions favorable to bioproductivity.
The extreme sedimentation rate of 3.4 cm a-1 calculated for the plumites from the upper-slope area
indicates a massive, nearly instantaneous (less than 150 years), terrigenous input corresponding to a
large outburst flood. We propose these interlaminated sediments to represent the high-latitude marine
record of Melt Water Pulse 1a (MWP-1a). Different bathymetric and oceanographic conditions
controlled locally the mode of glacial retreat, resulting in different thickness of plumites on the upper
continental slope of the Storfjorden and Kveithola TMFs. It is possible that the southern part of
Storfjorden TMF received additional sediments from the deglaciation of the neighboring Kveithola ice
stream.reservedmixedR.G. Lucchi; A.Camerlenghi; M. Rebesco; E. Colmenero-Hidalgo; F.J. Sierro; L. Sagnotti; R.Urgeles;R. Melis; C. Morigi; M.-A. Bárcena; G. Giorgetti; G. Villa; D. Persico; J.-A. Flores; A.S. Rigual-Hernández; M.T. Pedrosa; P.Macri; A. CaburlottoR. G., Lucchi; Camerlenghi, Angelo; M., Rebesco; E., Colmenero Hidalgo; F. J., Sierro; L., Sagnotti; R., Urgeles; Melis, Romana; C., Morigi; M. A., Bárcena; G., Giorgetti; G., Villa; D., Persico; J. A., Flores; A. S., Rigual Hernández; M. T., Pedrosa; P., Macri; A., Caburlott
Stellar variability from Dome A, Antarctica
The Antarctic plateau is one of the best observing sites on the surface of the Earth thanks to its extremely cold, dry, stable and transparent atmosphere conditions. Various astronomical activities are underway there and the Chinese Center for Antarctic Astronomy (CCAA) is dedicated to developing Antarctic astronomy at the highest point, Dome A or the Chinese Kunlun station. So far a large number of images have been collected from a 14.5-cm quad-telescope called the Chinese Small Telescope ARray (CSTAR) and the first two of a trio of 50-cm Antarctic Survey Telescopes (AST3-1 and AST3-2)