It is the northern of two
lava domes which lie at the southern end of the Sierra de Calalaste[4] and on its eastern flank.[5] A 1.5 kilometres (0.93 mi) wide horseshoe-shaped collapse scar dominates the edifice of the lava dome and has generated large debris block.[6] and hummocky debris.[7] A second edifice developed within the collapse scar.[8] The total volume of the volcano is about 5.19 cubic kilometres (1.25 cu mi).[9]
The volcano 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.[10] The upper unit is formed by
ignimbrites and
pyroclastic density current deposits.[11]
For the past five millennia,[14] 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.[15][16]
Eruption history
The lava dome at Cueros de Purulla is 400,000 ± 100,000 years old[17] and produced volcanic units that resemble the older volcanics of Cerro Blanco; some were originally attributed to that volcano.[5] At first, "coulee"
lava flows were erupted and a large
lava dome grew. After the collapse, the same processes rebuild part of the volcano. Notably, there is no indication that Cueros de Purulla produced
block-and-ash flows.[13] Based on the stratigraphic relations with volcanic rocks from Cerro Blanco, Cueros de Purulla was active during the last 73,000 years.[18]
The "El Paso ash" in the Tafí valley was emplaced between 11802 and 4289 years
before present and may originate at Cueros de Purulla volcano.[19] A large eruption occurred during the
Holocene, 7820 years
before present (i.e. about 5870 BC).[20] Deposits from this eruption form the Cerro Paranilla Ash in the
Calchaquí Valleys,[21] while a correlation to the 12,000-4,300 years before present[22] so-called "VO ash" is unlikely.[23] The eruption was highly explosive, forming a buoyant cloud[24] and depositing tephra as far as
Cafayate in the
Salta Province.[25] However, it is possible that deposits close to Cueros de Purulla might originate from activity at Cerro Blanco instead.[26]
^
abSeggiaro, Raúl E.; Hongn, Fernando D.; Castillo, Alfredo; Pereyra, Fernando Xavier; Villegas, Daniela; Martínez, Liliana; González, Osvaldo Edgar (2006).
Hoja Geológica 2769-II Paso San Francisco. Servicio Geológico Minero Argentino. Instituto de Geología y Recursos Minerales. p. 26.
^Roy, R.; Cassard, D.; Cobbold, P. R.; Rossello, E. A.; Billa, M.; Bailly, L.; Lips, A. L. W. (1 November 2006). "Predictive mapping for copper–gold magmatic-hydrothermal systems in NW Argentina: Use of a regional-scale GIS, application of an expert-guided data-driven approach, and comparison with results from a continental-scale GIS". Ore Geology Reviews. 29 (3): 286.
doi:
10.1016/j.oregeorev.2005.10.002.
hdl:11336/16669.
ISSN0169-1368.
^Osterrieth, Margarita; Alvarez, María Fernanda; Gallardo, Juan Fernando; Saavedra, Julio; Fernandez-Turiel, Jose-Luis; Rodriguez-Gonzalez, Alejandro; Perez-Torrado, Francisco J.; Rejas, Marta (10 July 2019). "Palaeoenvironmental use of silicophytoliths in soils and palaeosols associated with Holocene volcanic ash deposits in north-western Argentina". Quaternary International. 522: 103.
Bibcode:
2019QuInt.522..103O.
doi:
10.1016/j.quaint.2019.07.001.
hdl:10261/185417.
ISSN1040-6182.
S2CID198418382.
^Osterrieth, Margarita; Alvarez, María Fernanda; Gallardo, Juan Fernando; Saavedra, Julio; Fernandez-Turiel, Jose-Luis; Rodriguez-Gonzalez, Alejandro; Perez-Torrado, Francisco J.; Rejas, Marta (10 July 2019). "Palaeoenvironmental use of silicophytoliths in soils and palaeosols associated with Holocene volcanic ash deposits in north-western Argentina". Quaternary International. 522: 104.
Bibcode:
2019QuInt.522..103O.
doi:
10.1016/j.quaint.2019.07.001.
hdl:10261/185417.
ISSN1040-6182.
S2CID198418382.