Palaeoenvironment reconstruction, volcanic evolution and geochronology of the Cerro Blanco subcomplex, Nevados de Chillán volcanic complex, central Chile
Nevados de Chillán Volcanic Complex, central Chile, has been active for at least 640 ka—a period spanning a number of glacial and interglacial periods. Geologic mapping, radiometric dating and geochemical analysis have identified six new volcanic units and produced four new 40Ar/39Ar ages for Cerro Blanco, the northern subcomplex of Nevados de Chillán volcano. Compositions range from dacite to basaltic-andesite and a new geologic map is presented. Examination of lava fracture structures on both newly mapped lavas and those mapped during previous studies has enabled interpretations of former eruptive environments. Palaeoenvironment reconstructions, combined with 40Ar/39Ar ages and comparison with the marine oxygen isotope record, show that at least three phases of volcanic activity have occurred during the evolution of Cerro Blanco: (1) a constructive, pre-caldera collapse period; (2) a period of caldera formation and collapse; and (3) a constructive period of dome growth forming the modern day volcanic centre. This style of volcanic evolution, whereby large-scale caldera collapse is followed by growth of a new stratocone is common at Andean volcanoes.
KeywordsVolcano–ice interaction Nevados de Chillán Cerro Blanco Palaeoenvironment reconstruction Snow-contact Caldera-collapse 40Ar/39Ar dating
The authors would like to thank Hugh Tuffen and Mike James for their valuable contributions in the field, along with Holly Frey and Charles Stern for their thorough reviews, all of which have considerably improved this manuscript. KM was funded by a NERC Studentship; JSG acknowledges receipt of a 2001 Lancaster University Small Grant; DM received support from the OU Science Staff Tutor research fund; and JAN would like to thank Sernageomin’s PRV and Fondecyt Project No. 1960186.
- Cas RAF, Wright JV (1987) Volcanic successions—modern and ancient. Allen & Unwin, LondonGoogle Scholar
- Clavero JE, Sparks SJ, Polanco E, Pringle MS (2004) Evolution of Parinacota volcano, Central Andes, Northern Chile. Rev Geol Chile 31(2):317–347Google Scholar
- Déreulle B, Déreulle J (1974) Los volcanes Cuaternarios de los Nevados de Chillán y reseña sobre el volcanismo Cuaternario de los Andes Chilenos. Estud Geol 30:91–108Google Scholar
- Harford CL, Pringle MS, Sparks RSJ, Young SR (2002) The volcanic evolution of Montserrat using 40Ar/39Ar geochronology. In: Druitt TH and Kokelaar BP (eds) The eruption of Soufrière Hills Volcano, Montserrat, from 1995 to 1999. Geol Soc London Mem 21:93–113. The Geological Society of London 2002Google Scholar
- Lowe JJ, Walker MJC (1997) Reconstructing quaternary environments, 2nd edn. Pearson Prentice Hall, EnglandGoogle Scholar
- Naranjo JA, Lara LE (2004) August–September 2003 small vulcanian eruption at the Nevados de Chillán Volcanic Complex (36°50′S), Southern Andes, Chile. Rev Geol Chile 31(2):359–366Google Scholar
- Naranjo JA, Chávez R, Sparks RSJ, Gilbert JS, Dunkley P (1994) Nuevos antecedentes sobre la evolución cuaternaria del complejo volcánico Nevados de Chillán. Congreso Geológico Chileno 7, Concepción, Chile, 1:342–345Google Scholar
- Pringle MS (1993) Age progressive volcanism in the musicians seamounts: a test of the hot spot hypothesis for the Late Cretaceous Pacific. In: Pringle MS, Sager WW, Sliter VW, Stein S (eds) The mesozoic pacific: geology, tectonics and volcanism. AGU Geophysical Monograph Series 77:187–215Google Scholar
- Taylor JR (1982) An introduction to error analysis. University Science Books, Mill Valley, CaliforniaGoogle Scholar
- Tuffen H, McGarvie DW, Gilbert JS, Pinkerton H (2002a) Physical volcanology of a subglacial-to-emergent rhyolitic tuya at Rauðufossafjöll, Torfajökull, Iceland. In: Smellie JL, Chapman MG (eds) Volcano–ice interaction on Earth and Mars. Geol Soc London Spec Pub 202:213–236Google Scholar