Famatinian magmatism in the SW Gondwana margin: A review focused on the Sierras Pampeanas (Argentina)

The Famatinian orogeny along the proto-Pacific margin of Gondwana, from Venezuela to northeastern Patagonia, was of the accretional type during the Paleozoic (Ordovician to Silurian). Information gathered from the Sierras Pampeanas (Argentina) reveals magmatism (plutonism and volcanism) between 490 and 465 Ma, with a peak at 473–467 Ma, similar to other regions along the margin. Metamorphic events in the middle crust occurred between 484 and 465 Ma, and at ca. 440 Ma. Recent reviews propose a lithospheric extension phase (>480 Ma) before contraction episodes (ca. 470 and 440 Ma). Magmatism transitioned from peraluminous to metaluminous intrusions, with prolonged mafic magmatism throughout. Mafic intrusions show a broad spectrum of isotope compositions (87Sr/86Srt = 0.705 to 0.711 and ƐNdt = +5 to −6) but with general trends toward isotopically enriched magmas. The main arc consists of tonalite-granodiorite magmas (ca. 480–470 Ma) with