Cueros de Purulla

The volcano lies in Catamarca Province of Argentina[2] 60–70 kilometres (37–43 mi) southeast of Antofagasta de la Sierra.[3] Cerro Blanco volcano lies 25 kilometres (16 mi) south of Cueros de Purulla.[1]

It is the northern of two lava domes which lie at the southern end of the Sierra de Calalaste.[4] The dome is accompanied by ignimbrites[1] and a debris deposit consisting of obsidian lies at the foot of the dome.[4] Two volcanic fallout units are associated with Cueros de Purulla. A lower fallout unit consisting of lapilli and volcanic ash extends several kilometres from the volcano, and remnants occur as far as 180 kilometres (110 mi) from it.[5] The upper unit is formed by ignimbrites and pyroclastic density current deposits.[6]

Volcanic rocks erupted at Cueros de Purulla include rhyolite. Mineralogically, the rocks contain allanite, amphibole, apatite, biotite, clinopyroxene, epidote, feldspar, ilmenite, magnetite, muscovite, quartz, titanite and zircon.[6] For the past five millennia,[7] the volcano has been used as a source of obsidian, which occurs at 4,380 metres (14,370 ft) in the form of blocks and nodules of various colours, and is of high quality.[3] Reportedly, gold and silver can be found at the volcano.[8][9]

The lava dome at Cueros de Purulla is 400,000 ± 100,000 years old.[10] A large eruption occurred during the Holocene, 7820 years before present (i.e. about 5870 BC).[11] Deposits from this eruption form the Cerro Paranilla Ash in the Calchaquí Valleys.[12] The eruption was highly explosive, forming a buoyant cloud[13] and depositing tephra as far as Cafayate in the Salta Province.[14]