Timing constraints on building an intermediate plutonic arc crustal section: U- Pb zircon geochronology of the Sierra Valle Fértil-La Huerta, Famatinian arc, Argentina

The Sierra Valle Fértil Range in northwestern Argentina exposes a tilted crustal section through the Ordovician Famatinian arc, from >25 km to shallow crustal paleodepths. Fourteen new U‐Pb zircon crystallization ages of magmatic rocks from Sierra Valle Fértil area show that this section of the arc was built over a short time interval during the Ordovician, between 485 and 465 Ma. Zircon rim ages demonstrate that high‐grade metamorphism and migmatization were synchronous with magmatic emplacement. Inherited ages in some of the plutonic rocks as well as detrital zircons in the metasedimentary framework suggest that the Famatinian arc was emplaced into a thick miogeoclinal cover to the thinned margin of the proto‐South American continent in the Ordovician, which represents a part of Gondwana. Docking of the Precordilleran terrane outboard of proto‐South America led to the cessation of arc magmatism in the Valle Fértil area and preservation of the arc in its early stages after