PALEOMAGNETISM OF A PERMO-TRIASSIC BIMODAL DIKE SWARM OF NORTHERN PATAGONIA

MARTINEZ DOPICO, C.I.; RAPALINI, A.E.; LUPPO, T.; MIGUEZ, M.; LÓPEZ, MÓNICA GRACIELA

LatinMag Letters

Universidad Nacional Autónoma de México

Lugar: Mexico; Año: 2016 vol. 6 p. 1 - 6

2007-9656

Paleomagnetic data was obtained from 16 sites collected from mafic and acid dikes (< 250 Ma) of theLa Esperanza Plutono-Volcanic Complex, outcropping in the northern Patagonia, Argentina. AF andthermal demagnetization procedures revealed mostly north-northwestern directions with moderate upwardinclinations on specimens from 13 out of 16 analyzed sites. Site mean direction for the dikes clusters aroundDm = 346°; Im = -60°, which allowed calculating a paleomagnetic pole for the La Esperanza dikes (LEpole), located at -82.5° (lat), 11.9° (long) (α95=10.9º; N=13, k=17). The magnetization is primary and mainlycarried by PSD magnetite and minor hematite as evidenced by textures observed by ore microscope and IRMand thermomagnetic curves. The LE pole is the first pole bracketed in age for the Permo-Triassic intervalfor central northern Patagonia calculated with a primary magnetization on igneous rocks. The comparisonof the position of the LE pole with other poles of Patagonia and neighbouring areas of Gondwana suggeststhat these blocks were already juxtaposed earlier than 250 Ma, as suggested in previous geologic models.