Onshore/Offshore geophysical survey in Danco coast. NW Antarctic Peninsula

VILAS, J. F.; TASSONE A.; LIPPAI, H,; HORMAECHEA, J. L.

Toronto. Canada

Simposio; American Geophysical Union (AGU), Joint Assembly; 2009

American Geophysical Union (AGU

Within an area of around 119 km2 at Danco Coast (64° 09´ SL y 60° 57´ WL) a geophysical onshore/offshore survey was carried out during the 2005-06, 2006-07 and 2008-09 Antarctic summers. The Upper Cretaceous to Tertiary volcanic rocks intruded by a granodioritic pluton which outcrop in coastal areas belongs to the Mesozoic magmatic arc. Leucocratic and melanocratic andesitic dykes hosted in granodiorite at Cierva Cove bear sulphide mineralization. The main structures consist of two fault systems of WNW-ESE and NE-SW orientation which delineate the morphology of onland areas and the shoreline. Our geophysical and geologic survey was directed to acquire new data to define the geometry, lateral relationships and tectonic development of the geologic units of the Mesozoic magmatic arc exposed in the western border of the Antarctic Peninsula (AP). The geologic survey included lithologic and structural sampling, a total of 531 rock cores were obtained for AMS and paleomagnetic studies. The bathymetric survey of Hughes bay (including Sierva and Santucci creeks) has been carried out with the aim of determining the geometric features and spatial distribution of the main submerged depressions and their onshore continuity. This information is very useful for geophysical surveys and for comparing the submerged and emerged morphostructure. The magnetic survey was carried out with two magnetometers of proton free-precession: a Scintrex ENVI GRAD (used as permanent base) and a Geometrics G856 magnetometer employed for sampling stations (which measured the intensity of the total magnetic field and worked synchronized with the base magnetometer in order to make the corresponding corrections). A total of 1670 registrations were acquired in the 5803 GPS fixed onland stations within an area of 2.55 km2. A Zodiac MK3 was employed for the offshore magnetic survey. 11672 stations constitute the magnetic grid in offshore areas, organized along broadly orthogonal sections with a total length of around 548 km.