A major volcaniclastic unit is associated with Archibarca, named the La Torre formation after the valley where its lower bright red unit reaches a thickness of 20 metres (66 ft). The red unit is formed from unconsolidated pyroclastics with spherical clasts (3 centimetres (1.2 in) up to 10 centimetres (3.9 in)). Granite and pumice are materials also present in this unit. The upper white unit is a thick pyroclastic flow from Archibarca. A 30 metres (98 ft) thick rhyolitic flow with banding structures is also present as well as an associated lava dome that intruded the La Torre formation on the volcano's southern side.[4]
Andesites from this volcano are partly derived from crustal assimilation, with the crustal component constituting 40% of total rock.: 103 [2] The Caballo Muerto and Archibarca ignimbrites may be derived from this volcano.[5]
References
^Kraemer, B.; Adelmann, D.; Alten, M.; Schnurr, W.; Erpenstein, K.; Kiefer, E.; van den Bogaard, P.; Görler, K. (March 1999). "Incorporation of the Paleogene foreland into the Neogene Puna plateau: The Salar de Antofalla area, NW Argentina". Journal of South American Earth Sciences. 12 (2): 157–182. doi:10.1016/S0895-9811(99)00012-7.
^Richards, Jeremy P.; Ullrich, Thomas; Kerrich, Robert (April 2006). "The Late Miocene–Quaternary Antofalla volcanic complex, southern Puna, NW Argentina: Protracted history, diverse petrology, and economic potential". Journal of Volcanology and Geothermal Research. 152 (3–4): 197–239. doi:10.1016/j.jvolgeores.2005.10.006.