Paleomagnetic study of Deception Island, South Shetland Islands, Antarctica.

BARALDO, ANDRéS; RAPALINI, AUGUSTO E.; BOEHNEL, HARALD; MENA, MABEL

GEOPHYSICAL JOURNAL INTERNATIONAL

Royal Astronomical Society

Lugar: London; Año: 2003 vol. 153 p. 333 - 343

0956-540X

SUMMARYA paleomagnetic study was carried out on recent volcanic rocks exposed on Deception Island(63.0◦S, 60.6◦W), Antarctica. Sampling comprised all stratigraphic units exposed onthe island, which include basaltic, andesitic and trachytic lavas, basaltic dykes and pyroclasticflows. Following stepwise thermal and alternating field demagnetization procedures, consistentcharacteristic remanence directions were determined at 21 sites, using principal-componentanalysis. The overall mean remanence direction for the Deception Island rocks is dec. 348.8◦,inc. −73.7◦, á95 = 4.4◦, N = 21, and is consistent within error with the geocentric axialdipole direction at the study locality. All of the studied rocks show normal polarity, indicatinga Brunhes Chron age. The only available radiometric date of 153 ± 46 kyr agrees with thisand suggests a minimum chronostratigraphic span of 100 kyr for the sampled rocks. The sitemean directions show a Fisherian distribution and dispersion values compatible with currentpalaeosecular variation models. No evidence of the far-sided or right-handed effect is foundin our data.Key words: Antarctica, Deception Island, Earth magnetic field, palaeomagnetism,palaeosecular variation, Quaternary.