CARACTERIZACIÓN PALEOMAGNÉTICA Y DE MAGNETOFÁBRICA DE LAS DOS SECUENCIAS QUE COMPONEN EL BATOLITO DE ACHALA, DEVÓNICO, SIERRAS PAMPEANAS (ARGENTINA)

GEUNA, S.; LÓPEZ DE LUCHI, M. G.; ESCOTEGUY, L.

Tandil

Congreso; Segunda Reunión Bienal de la Asociación Latinoamericana de Paleomagnetismo y Geomagnetismo (LATINMAG); 2011

Asociacion Latinoamericana de Paleomagnetismo y Geomagnetismo

The Achala batholith (31o30´S, 64o45´W, Córdoba, Argentina) is a major magmatic complex of the Sierras Pampeanas, emplaced in a metamorphic?plutonic basement during the Achalian Orogeny (Devonian). It is mainly a porphyritic to coarse-grained equigranular monzogranite (Sequence I), with crystallization age of ~380 Ma, followed by fine-grained, biotite-muscovite granites of ~370 Ma (Sequence II). Thirty-six sites were studied for paleomagnetism and anisotropy of magnetic susceptibility (AMS), mostly in the Sequence II, and combined with published data. Overall, the batholith is weakly magnetic, and it shows ilmeno-haematite as magnetic carrier of a stable remanence. Thermal demagnetization up to 620-640oC isolated steeply dipping remanence directions. Both Sequences provided different palaeomagnetic poles, not far from the 380-370 Ma segment of the Gondwana apparent polar wander path. The AMS is higher for Sequence II and the AMS ellipsoid is aligned with the direction of shearing active during its emplacement.