Geological evolution of the Pacific margin of Western Antarctica: sea-floor spreading and plate tectonics

In English:

The cruise GEBRAP'96 has been carried out on board RV Hesperides
from 03.12.96 to 06.01.97 in the northern Bellinghausen Sea, the
Gerlache Strait and Bransfield Basin, Western Antarctica. The
scientific task carried out include detailed mapping of the seafloor
relief by means of multibeam and single beam echo-sounders, the study
of the sedimentary cover at various scales with BPS and high to medium
resolution seismic reflection profiling, measuring of the total
magnetic field and the gravity field with a marine magnetometer and
gravity-meter, dredging of the submarine volcanic edificies of the
Bransfield central subbasin which were identified in the former cruise
GEBRA '93, sediment coring with a gravity, corer, and the systematic
monitoring of the krill biomass with a biological
echo-sounder.

Several complementary tasks to the previous ones have
been also done, together with the usual automatic recording of
environmental data. It is worth to be mentioned the acquisition of
vertical velocity profiles of the sea water by means of Sippican
sensors, and the continuous recording of physical and biological
(fluorescence) properties of the sea surface waters with a
thermo-salinitymeters and fluorometer pair, and the continuous
recording of meteorological data. Also, the movements of the vessel
during its moorings, as well as the going and back tracks to the
mooring position off the BAE in Livingston Island allowed to draw a
detailed bathymetric map of this mooring site.

En Espanol:

La campana GEBRAP '96 se ha desarrollado a bordo del
B.I.O. Hesperides entre los d?as 03.12.96 y 06.01.97 en
aguas del Mar de Bellinghausen septentrional, el Estrecho de Gerlache
y la Cuenca de Bransfield. En la misma se han llevado a cabo labores
de cartografia morfologica del lecho marino con sondas de
multihaz y de monohaz, de estudio del recubrimiento sedimentario a
distintas escalas con sonda BPS y sismica de reflexion de
alta y media resolucion, de medicion del campo
magnetico total y del campo gravitatorio mediante
magnetometro y grav?metro marinos, de dragado de los
edificios volcanicos submarinos de la subcuenca central de
Bransfied cartografiados en una campana previa (GEBRA '93), de
obtencion de testigos de sedimento con sacatestigos de gravedad,
y de seguimiento sistem?tico de la biomasa de krill mediante una
sonda biologica.

Asimismo se han realizado labores complementarias a las anteriores
y se ha mantenido el registro automatico rutinario de datos
ambientales. Cabe citar, en este sentido, la obtencion de
perfiles de velocidad en el agua mediante sondas Sippican, mediciones
en continuo de parametros f?sicos y biologicos
(fluorescencia) de las aguas superficiales con termosalinometro y
fluorometro, y registro cont?nuo de datos
meteorologicos. Ademas, aprovechando los borneos del buque
durante el fondeo en la BAE, en Livingston, asi como sus
recorridos de ida y vuelta, se levanto un mapa batimetrico
de gran precision y con cobertura total de dicho fondeadero.