Tectono-sedimentary evolution of the western Gondwana margin during the Silurian: Insights from new sedimentological and geochronological analysis of the Villacorta Formation

Abstract

The Villacorta Formation is a Silurian sedimentary succession exposed in a restricted area in the central-westernFamatinian Belt, with its type locality at Los Oitos Creek. This formation represents an exceptional and wellpreservedSilurian record. Detailed facies analysis reveals five distinct facies associations that record a progradationaltrend from subtidal sandbars and tidal channels to a tide-dominated deltaic system. To constrain itsprovenance, we report U–Pb geochronological analysis of detrital zircon from a sandstone sample collected fromthe upper portion of the stratigraphic profile. The sample yielded a nearly unimodal age distribution dominatedby Lower Ordovician ages, indicating a prevailing source in the Famatinian batholith. This detrital zirconsignature resembles the Lower Ordovician age cluster that also occurs in coeval Silurian–Devonian units of thePrecordillera (e.g., Los Espejos Formation), supporting the existence of a broader Silurian basin system thatstretches from the Famatinian orogen into the Cuyania terrane. These findings suggest that the Silurian Seaextended as far west as the present-day Famatinian batholith. A significant outcome of this study is the recognitionof the Villacorta Formation as a synorogenic deposit that predates the collapse of the Famatinian orogenand the exhumation of the Cuyania basement.