MAGNETIC SURVEY IN THE AREA OF THE COAST DE DANCO, AMONG PUNTA PY CABO END VIVOT. NW ANTARCTIC PENINSULA.

TASSONE, ALEJANDRO; LIPPAI, H.; VILAS, JUAN F.

Moscone Center West, 800 Howard Street, San Francisco, CA, USA

Otro; AGU Fall Meeting; 2006

AGU

A geophysical campaign has been developed along Danco Coast –between Py Point to the south, and Vivot Cape to the north- with the aim of 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. Rock outcrops mostly belong to plutonic bodies of granitic through tonalitic composition, and rhyolites, andesites and basaltic rocks. The geologic survey included the lithologic and structural sampling, a total of 216 rock cores were obtained for AMS and paleomagnetic studies. The acquired data have been GPS referred. The magnetic survey was carried out with two magnetometers of the proton free-precession: a Scintrex ENVI GRAD (used as permanent base which registered continuously in cycles every 30 seconds and obtained about 88900 data) and a Geometrics G856 magnetometer employed for sampling stations (which measured the intensity of the 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 334 GPS fixed onland stations. A Zodiac MK5 was employed for the offshore magnetic survey. The Geometrics magnetometer was located on prow; GPS data were acquired both in static and dynamic mode, with plotting speed of 2´30” and stations each 90 m and/or 25 m in critic localities. 5162 stations constitute the magnetic grid in offshore areas, organized along orthogonal sections with a total length of around 380 km. The magnetic anomaly map produced with the acquired data shows five N-S-oriented belts of maximums up to 3000 nT separated by minimum of -500nT. The preliminary interpretation of the data might infer the offshore prolongation of volcanic levels such as those observed in onland areas. Results of the magnetic survey along with the paleomagnetic and petrologic information presently in process will provide new insights of the western border of Antarctic Peninsula and its geodynamic relation with other segments of the old Gondwana margin.