Plume subduction beneath the Neuquén Basin and the last mountain building stage of the Southern Central Andes

GIANNI, GUIDO M.; PESCE, AGUSTINA; GARCIA HECTOR; LUPARI MARIANELA; SEBASTIAN CORREA; SILVINA VALERIA NACIF; FOLGUERA ANDRES

Opening and closure of the Neuquén Basin in the Southern Andes

Springer

Año: 2019;

The occurrence of a Neogene shallow subduction stage, as well as, a Pliocene tearing and steepening of the Nazca plate in the Southern Central Andes are well established. However, a satisfactory explanation for the origin and connection between these complex processes is still elusive. In this contribution, we revise the late Cenozoic tectonic and magmatic evolution of the Southern Central Andes between 35° and 38°S and discuss different proposals for the Miocene slab shallowing and its Pliocene destabilization. Recent plate-kinematic reconstructions show that Neogene arc-front expansion linked to slab shallowing, fold-belt reactivation in the Main Cordillera and intraplate contraction in the San Rafael Block correlate with the subduction of the ancient Payenia plume, a deep mantle anomaly potentially rooted in the lower mantle. Also, the Nazca slab tear determined from tomographic analyses and subsequent slab steepening may also be a direct consequence of this plume subduction process. Considering the westward drift of South America and the presence of several neighbor hotspots over the Nazca plate, the Payenia plume overriding could be the first of future episodes of plume-trench interaction in the Andes.