MAGNETIC FABRICS OF THE LATE SILURIAN VILLACORTA FORMATION, SIERRA DE FAMATINA, ARGENTINA

BELLANTE, MICAELA; CUKJATI, ANDRÉS; FRANCESCHINIS, PABLO R.; MARENSSI, SERGIO; RAPALINI, AUGUSTO E.

Río de Janeiro

Congreso; LatinMag VII Biennal Meeting; 2023

Asociación Latinoamericana de Paleomagnetismo y Geomagnetismo

The Villacorta Forma􀆟on was recently discovered and described outcropping on the western flank of the Fama􀆟na Ranges in NW Argen􀆟na. It is a clas􀆟c sequence of around 500 meters thick, dominated by fine to medium-grained sandstones. Palynological associa􀆟ons found in the upper levels suggest a Late Silurian age, which has apparently been confirmed by yet unpublished detrital zircons U-Pb ages. This unit has been subdivided into four sec􀆟ons. The second one, characterized by purple fine grain sandstones was sampled for a paleomagne􀆟c and magne􀆟c fabric study. Preliminary results from the later indicate a coherent magne􀆟c fabric that can be interpreted of deposi􀆟onal origin but with some tectonic influence. K3 axis are dominantly sub-ver􀆟cal, in paleohorizontal coordinates, with an incipient subver􀆟cal girdle developed together with K2 axes. Meanwhile K1 axes show a dis􀆟nct grouping around an NNW-SSE subhorizontal direc􀆟on which is subparallel to the axis of a roughly N-S, 2 km wavelength, an􀆟cline affec􀆟ng the Villacorta Forma􀆟on. This disposi􀆟on is consistent with a magne􀆟c fabric influenced by the compressive tectonic deforma􀆟on, assigned to the Chañic phase, that affected the western margin of Argen􀆟na in middle to late Devonian 􀆟mes.