Resumen
This study is focused on the analysis of volcanic deposits that crop out at the middle portion of the Las
Planchadas range, northern part of the Famatina System in Argentina. These volcanic rocks are records of an Ordovician
effusive basaltic volcanism that took place under subaqueous marine conditions. Along the study area crop out an
Arenigian volcanic and volcaniclastic rocks succession with massive and autoclastic lavas, hyaloclastites of basaltic
composition and volcaniclastic sandstones and mudstones. Large volumes of the volcanic deposits were strongly affected
by fragmentation processes during their subaqueous emplacement and in situ accumulated as basaltic breccias. The same
volcanic-volcaniclastic association crops out to the south of the Las Planchadas range, forming a basaltic belt with similar
characteristics. The geochemical features of the basalts are compatible with depleted mid-ocean ridge basalt (MORB)-
like source for the magma, with contribution of subducted related components such as water rich marine hemipelagic
sediments, compatible with a back arc geotectonic setting developed along the northern part of the Famatina System
during the Arenigian.