24°16′S 66°27′W / 24.267°S 66.450°W / -24.267; -66.450[1]Nevados de Pastos Grandes is a Miocene volcanic centre in the Puna,[2] Salta province, Argentina.
[7] The Pleistocene glaciation has excavated cirques and U-shaped valleys in the western and northern side of Azufre and Gordo above 4,500 metres (14,800 ft).
It has left talus and moraines on the upper flanks of the volcano as well as exposing hydrothermally altered areas, chiefly on the western side of the range.
As is typical for many Puna volcanoes, the first lava flows that were erupted are dacitic and are exposed in the northern and eastern flanks.
In this view, the last activity coincides with the cessation of large ignimbritic volcanism in the northern Puna and is probably linked to a steeper subduction of the Nazca Plate.
[11][12] The volcanic centre is underpinned by an Ordovician basement including metamorphed flysch and phyllites on the western side of the complex.
[1] A unique volcano La Pava-Ramadas is found north of Queva and has generated ash falls as far as the Subandean ranges 8.75 million years ago.
[3] Nevado de Pastos Grandes is a major polymetallic district, including lead, silver and tin.
[12] The area is cold and has an arid climate typical of the Altiplano,[4] with less than 500 millimetres per year (20 in/year) precipitation falling mainly during the summer monsoon.
[8] The town of San Antonio de los Cobres is located 53 kilometres (33 mi) northeast.
[5] The Alero Cuevas archeological site is located west of Nevados de Pastos Grandes and depended on water coming from the range.