Geological and paleoceanographic evolution of the South Atlantic and the adjacent Antarctic margins
Entry ID: CNDA-ESP_ANT93-1008-C03-HE014

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Summary
Abstract: In English:

The GEBRA '93 survey was carried out in December 1993 in the waters
of Bransfield Strait and adjacent areas, on board B.I.O. Hesperides.

Different types of measurements were performed during the survey:
swath bathymetric sounding; single-channel seismic reflection, BPS
bottom parametric source and magnetic profiling, and gravity coring;
and several instruments were moored. In total, an area of 17.000 Km2
of sea floor, at an average depth of about 1.500 m. has been covered
by the bathymetric swaths. About 1.500 km. of seismic, parametric and
magnetic profiles were acquired simultaneously (total: 5.500 km). Two
gravity cores of 2.5 m. and 4.5 m. were obtained. Seven current
meters, 3 tide gauges, one wave buoy and 3 acoustic release systems
were deployed. These different activities were carried out during 21
effective working days.

The abundant data acquired have permitted to characterize in great
detail the morphostructure, sedimentary cover and magnetic anomalies
of the study area. The GEBRA '93 swath bathymetry data cover an area
between 49?30' W and 60?30'W with a width of 30' of latitude that
comprises the Bransfield Basin and the western termination of the
South Scotia Ridge.

Amongst other relevant results, the GEBRA '93 survey has clearly
revealed the existence of several large volcanic edifices in the
Central Bransfield Basin, and the presence of a major submarine valley
on the continental slope of the Antarctic Peninsula margin, in the
prolongation of the Antarctic Channel. This submarine valley has been
named "GEBRA Valley". The Eastern Bransfield Basin has an extremely
complicated morphology mainly as a result of the interference between
NE-SW (Bransfield) and E-W (South Scotia Ridge) structural
directions.

The interpretation of the acquired geophysical data and the
analysis of the sediment samples will provide important new
information and contribute to a better knowledge of the Antarctic
continenetal margins and of the paleoceanographic evolution of the
area.

Scientists of different institutions participated into the GEBRA
'93 survey: the University of Barcelona, the Institute of Marine
Sciences of Barcelona, the Spanish Institute of Oceanography, the
University of Salamanca, the University of Gent (Belgium) and Rice
University (USA). The survey took place in the framework of the
coordinated programme "Geologic and paleoceanographic evolution of the
South Atlantic basins and adjacent Antarctic margins", and was funded
by CICYT.

En Espanol:

La campana GEBRA '93 se ha desarrollado en aguas del Estrecho
de Bransfield y zonas proximas entre los dias 3 y 24 de Diciembre
de 1993, a bordo del B.I.O. Hesperides.

En ella se han llevado a termino trabajos de barrido con
multihaz, sismica de reflexion de monocanal, sonda
parametrica BPS, magnetometr?a, extraccion de testigos
de gravedad y fondeo de instrumentos. En total se han barrido 17.000
km2 del fondo marino, con una profundidad media de 1500 m., se han
registrado simultaneamente 1.500 km. de lineas de sismica,
sonda parametrica BPS y magnetometria (total 4.500 Km.), se
han obtenido dos testgos de gravedad de 2.5 m. y 4.5 m. de longitud, y
se han fondeado 7 correntimetros, 3 mareografos, una boya de
oleaje y 3 liberadores acusticos. Todo ello en 21 dias
efectivos de trabajo.

Los abundantes datos obtenidos han pernitido caracterizar con gran
detalle la morfoestructura, el recubrimiento sedimentario y las
anomalias magneticas del area estudiada. Los datos de
multihaz de GEBRA '93 cierran la cobertura total de un arco de 11
degrees de longitud (49 degrees 30 minutes W hasta 60 degrees 30
minutes W) y una anchura media de 30 minutes de latitud, que ocupa la
Cuenca de Bransfield y el segmento occidental de la Dorsal Sur de
Scotia.

Entre otras aportaciones relevantes, se ha puesto de manifiesto la
existencia de varios edificios volcanicos de grandes dimensiones
en el fondo de la subcuenca central de Bransfield, y de un gran valle
submarino en el margen antartico, aguas afuera del Canal
Antartico. Dicho valle ha recibido el nombre de Valle Gebra. La
subcuenca oriental de Bransfield presenta una morfolog?a
extremadamente compleja debido en gran medida a la interferencia entre
las direcciones estructurales de la cuenca de Bransfield (NE-SW) y de
la Dorsal Sur de Scotia (E-W).

La interpretacion definitiva de los datos geofisicos
adquiridos y el analisis de los testigos de sedimentos
aportaran nuevas informaciones que contribuican
significativamente al conocimiento de la evolucion
geodinamica de la Cuenca de Bransfield y de su vulcanismo, de la
Estratigrafia Sismica de los margenes continentales
antarticos, y de la evolucion paleoceanografica de la
region.

Han participado en GEBRA '93 investigadores de la Universidad de
Barcelona, del Instituto de Ciencias del Mar de Barcelona, del
Instituto Espanol de Oceanografia, de la Universidad de
Salamanca, de la Universidad de Gante (Belgica) y de la
Universidad de Rice (Estados Unidos). Esta campana ha sido la
segunda del programa coordinado "Evolucion geologica y
paleoceanografica del Atlantico Sur y de las cuencas y
margenes antarticos adyacentes", financiado por la CICYT.

Related URL
Link: VIEW PROJECT HOME PAGE
Description: In English: Information on the vessel's Hesperides,
oceanographic expeditions can be found on this page. The information
includes a summary of the scientific results, participating agencies,
etc.


En Espanol: En esta pagina se encuentra
informacion sobre la campanas realizadas por el Buque
Oceanografico Hesperides: Resumen de los resultados
cientificos, organismos participantes..etc.


Geographic Coverage
 N: -60.0 S: -64.0  E: -50.0  W: -61.0

Temporal Coverage
Start Date: 1993-12-03
Stop Date: 1993-12-24


Location Keywords
CONTINENT > ANTARCTICA > Bransfield Strait
GEOGRAPHIC REGION > POLAR


Science Keywords
ATMOSPHERE >ATMOSPHERIC PRESSURE >ATMOSPHERIC PRESSURE MEASUREMENTS    [Definition]
ATMOSPHERE >ATMOSPHERIC TEMPERATURE >AIR TEMPERATURE    [Definition]
ATMOSPHERE >ATMOSPHERIC WATER VAPOR >HUMIDITY    [Definition]
ATMOSPHERE >ATMOSPHERIC WATER VAPOR >WATER VAPOR    [Definition]
ATMOSPHERE >ATMOSPHERIC WINDS    [Definition]
ATMOSPHERE >ATMOSPHERIC RADIATION >SOLAR RADIATION    [Definition]
OCEANS >BATHYMETRY/SEAFLOOR TOPOGRAPHY >SEAFLOOR TOPOGRAPHY    [Definition]
OCEANS >BATHYMETRY/SEAFLOOR TOPOGRAPHY >FRACTURE ZONES    [Definition]
OCEANS >MARINE GEOPHYSICS >MARINE GRAVITY FIELD    [Definition]
OCEANS >MARINE GEOPHYSICS >MARINE MAGNETICS >MAGNETIC ANOMALIES    [Definition]
OCEANS >BATHYMETRY/SEAFLOOR TOPOGRAPHY >OCEAN PLATEAUS/RIDGES    [Definition]
OCEANS >BATHYMETRY/SEAFLOOR TOPOGRAPHY >SEAMOUNTS    [Definition]
OCEANS >OCEAN OPTICS >FLUORESCENCE    [Definition]
OCEANS >OCEAN TEMPERATURE >WATER TEMPERATURE    [Definition]
OCEANS >SALINITY/DENSITY >CONDUCTIVITY    [Definition]
OCEANS >SALINITY/DENSITY >SALINITY    [Definition]
OCEANS >MARINE GEOPHYSICS >PLATE TECTONICS >SUBDUCTION    [Definition]


ISO Topic Category
CLIMATOLOGY/METEOROLOGY/ATMOSPHERE
ELEVATION
GEOSCIENTIFIC INFORMATION
OCEANS


Platform
SHIPS    [Information]


Instrument
GRAVIMETERS    [Information]
SEDIMENT CORERS    [Information]
THERMOSALINOGRAPHS    [Information]
MAGNETOMETERS    [Information]
GPS >Global Positioning System    [Information]
SEISMIC REFLECTION PROFILERS    [Information]
ADCP >Acoustic Doppler Current Profiler    [Information]
ECHO SOUNDERS    [Information]
FLUOROMETERS    [Information]


Originating Center


Data Center
Unidad de Tecnologia Marina, Consejo Superior de Investigaciones Cientificas, Espana    [Information]
Data Center URL: http://www.utm.csic.es/

Data Center Personnel
Name: MIGUEL ANGEL OJEDA
Phone: +34932216416
Email: maojeda at utm.csic.es
Contact Address:
Centro Mediterraneo de Investigaciones Marinas y Ambientales
CSIC
Unidad de Tecnologia Marina
Paseo Maritimo, 37-39
City: Barcelona
Postal Code: 08003
Country: SPAIN



Distribution
Distribution_Media: CD-ROM, DAT tape
Distribution_Format: ASCII, BINARY


Personnel
ANTONIO BARRAGAN SANABRIA
Role: DIF AUTHOR
Phone: +34913495731
Fax: +34913495929
Email: a.barragan at igme.es
Contact Address:
Centro Nacional de Datos Antarticos
Instituto Geologico y Minero de Espana
c/Rios Rosas 23
City: Madrid
Postal Code: 28003
Country: SPAIN


MIGUEL CANALS
Role: INVESTIGATOR
Phone: +3434021360
Fax: +3434021340
Email: miquel at natura.geo.ub.es
Contact Address:
Facultad de Geologia
Universidad de Barcelona
Nucleo Universitario de Pedralbes
City: Barcelona
Postal Code: 08071
Country: Spain



Creation and Review Dates
Last DIF Revision Date: 2003-09-24

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