Magnetic Fabrics and Paleomagnetism of the El Nihuil Mafic Unit, -San Rafael Block, Mendoza, Argentina

RAPALINI, AUGUSTO; WALTHER, ANA MARÍA; CINGOLANI, CARLOS

Pre-Carboniferous Evolutions of the San Rafael Block, Argentina. implications in the SW Gondwana Margin. Series Springer Earth System Sciences

Springer Nature

Lugar: Cham; Año: 2017; p. 127 - 136

Abstract A reconnaissance magnetic fabric and paleomagnetic study was carriedout on the El Nihuil mafic unit exposed in the San Rafael Block, MendozaProvince, Argentina. Sampling comprised eight sites on three different lithologies.While sites N1 and N2 corresponded to gneisses, N3 to N6 were located on doleriteoutcrops. Sites N7 and N8 were situated on the Loma Alta gabbro, although site N8corresponded to a dolerite intruding the gabbro. The magnetic fabric shows that thebulk susceptibility ranges from 4.9 × 10−4 SI to 1.7 × 10−2 SI, with the gabbroshowing the lowest values and the dolerite the highest. Despite the differentlithologies all sites showed a low anisotropy degree and an oblate fabric.Distribution of foliation planes shows a dominant NW trending describing anantiformal shape for the whole unit. Lineations were in most cases of low angle.Most samples showed well-defined but scattered remanence directions whichindicate that no significant paleomagnetic data can be obtained from El Nihuil maficunit.Keywords Mesoproterozoic basement Ordovician dolerites Paleomagnetic data