Stratovolcano in Putre, Chile
Lauca is a 5,140 metres (16,860 ft)[1] high andesitic stratovolcano in the Central Volcanic Zone of the Andes on the Altiplano in northern Chile. Administratively it is located in Putre, Arica y Parinacota Region. The volcano was active during the Late Miocene from 10.5 million years ago onwards. A major ignimbrite collapsed the volcano in the Late Pliocene.
Geology
Andesites from the Lauca volcano, active in the Late Miocene as of 10.5 million years ago,[3] exist in two groups, plagioclase rich ones which underwent alteration and fine grained silicic ones that are fresher.[1] The territory is underpinned with a crust formed from rocks of Precambrian to Cretaceous age, with thicknesses up to 70 kilometres (43 mi).[2] Amphibole rich lava flows formed a uniform volcanic cone. A later major ignimbrite eruption caused the collapse of the centre and formed the Lauca ignimbrite.[1] A caldera is present, with a lava dome at the northeastern rim.[1]
The Lauca ignimbrite has a thickness up to 150 metres (490 ft), covering the El Diablo Formation in parts and filling the Lluta Canyon. Ar-Ar ages for this rhyolitic ignimbrite have been determined at 2.73 ± 0.02 Ma based on sanidine analysis and 2.87 ± 0.05 Ma from biotite.[4] The Lauca ignimbrite has been correlated to the Pérez ignimbrite in Bolivia and the Pachía ignimbrite in southern Peru.[5] Along the Copaquilla-Tignámar Fault, uplifting the eastern side over the western side,[6] the Lauca ignimbrite has been displaced over 100 to 150 metres (330 to 490 ft), indicative of tectonic activity after deposition in the Late Pliocene.[7] In parts, the Lauca ignimbrite is covered by conglomeratic terrace deposits.[8]
Chile
