HR: 14:45h
AN: GP23A-04 [Abstracts]
TI: New Early Paleozoic Paleomagnetic Poles From NW Argentina: a Reappraisal of Tectonic Models
AU: * Spagnuolo, C M
EM: cspagnuolo@gl.fcen.uba.ar
AF: Ingeodav, Depto. Cs. Geológicas, F.C.E.y N., Universidad de Buenos Aires,
Pabellón 2, Ciudad Universitaria, Buenos Aires, C1428EHA, Argentina
AU: Rapalini, A E
EM: rapalini@gl.fcen.uba.ar
AF: Ingeodav, Depto. Cs. Geológicas, F.C.E.y N., Universidad de Buenos Aires,
Pabellón 2, Ciudad Universitaria, Buenos Aires, C1428EHA, Argentina
AU: Astini, R A
EM: raastini@com.uncor.edu
AF: Laboratorio de Análisis de Cuencas, F.C.E.F.y N., Universidad Nacional de
Córdoba, Av. Velez Sarsfield 1611, Córdoba, X5016GCA, Argentina
AB:
A paleomagnetic study carried out on Early Ordovician volcanic units in the Famatina Ranges of NW Argentina
yielded a pre-tectonic paleomagnetic pole at 32.7°S, 4.3°E, (5.6°/ 8.6°, N=14 sites) that is
consistent with four previous Early Ordovician poles from the Famatina - Eastern Puna Eruptive Belt of NW
Argentina. However, these five poles are rotated around 50° clockwise respect to the coeval reference pole
of Gondwana. Our new results seem to confirm previous models of this belt as a paraauthocthonous rotated
terrane on the southwestern margin of Gondwana. However, a recent paleomagnetic pole from the Late
Cambrian Mesón Group, at the Eastern Cordillera of NW Argentina, corresponding to the Gondwana foreland
(4.5°S, 359.0°E, dp=5.5°, dm=8.8°, n=26 samples) and preliminary paleopoles obtained
from the same unit and the latest Cambrian - Early Ordovician Santa Victoria Group at other three localities in the
same region, also indicate an anomalous pole position rotated some 40° clockwise respect to the
reference pole for Gondwana. These results suggest that the postulated model of a rotated terrane for the
Famatina-Eastern Puna belt must be reconsidered. Different alternative scenarios including the possibility of an
Early Paleozoic displacement of the whole basement of the Eastern Sierras Pampeanas of Argentina ("Pampia")
will be explored.
DE: 1525 Paleomagnetism applied to tectonics: regional, global
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Joint Assembly