Abstract
Geologic mapping on a scale of 1:10000 and detailed stratigraphic studies of lava flows and tephra deposits of the Arenal-Chato volcanic system reveal a complex and cyclic volcanic history. This cyclicity provides insight into the evolution of magma batches during the growth of the andesitic volcanic system. The Arenal and Chato volcanoes have a central zone comprised of a lava armor and a distal zone comprised of a tephra apron. During Arenal's last two eruptive periods major craters formed near intersections of regional fractures at the lava armortephra apron transition. We suggest that such intersections are potential sites for future major explosions. The earliest rocks, i.e., the Chato lava flows, range in composition from basaltic andesite to andesite. These rocks, except for the andesitic domes of Chatito and La Espina, appear to have evolved from a common parental magma. The last active period of Chato volcano occurred 3550 B. P. The earliest known activity of Arenal volcano is 2900 B. P. Arenal lava flows have 54–56 wt% SiO2 and may be subdivided into a high-alumina group (HAG, Al2O3 = 20 wt%) and a low-alumina group (LAG, Al2O3 = 19 wt%). Compared to the HAG, the LAG also has smaller amounts of incompatible elements and higher amounts of FeO and MgO. Arenal tephra deposits were emplaced by Plinian-Sub-Plinian explosions occurring at 300±150-yr intervals. These deposits are compositionally zoned and alternate between dacite and basalt. The stratigraphy reveals an apparent magmatic cycle consisting of (a) dacitic-andesitic tephra, (b) HAG lava flows, (c) LAG lava flows, and (d) andesitic-basaltic tephra. This magmatic cycle is repeated four times during Arenal's history and is interpreted to have developed by the crystal fractionation and crystal redistribution of a single magma batch. The period of this cycle, and consequently the “life” of a magma batch, is about 800 years. If the cyclic pattern continues, a basaltic explosive phase may occur in the next 250 years.
Similar content being viewed by others
References
Alvarado GE (1984) Aspectos petrologicos y geologicos de los volcanes y unidades lavicas del Cenozoico Superior de Costa Rica. Thesis, Universidad de Costa Rica, Costa Rica, p 183
Alvarado, Barquero R Las senales sismicas del Volcan Arenal (Costa Rica) y su relacion con las fases eruptivas, 1968–marzo 1986. Ciencia y Tecnologia, Costa Rica (in press)
Barquero J (1978–1986) Boletin de Vulcanologia. Escuela de Ciencias Geograficas, Universidad Nacional, Heredia, Costa Rica, p 1–16
Bennett FD, Raccichini S (1977) Las erupciones del volcan Arenal, Costa Rica. Revista Geografica de America Central, Costa Rica, 5–6:7–35
Bonasia V, Casertano L, Imbo G, Oliveri del Castillo A (1967) Variazioni morfologiche del gran Cono Vesuviano e conformazione di alcuni crateri felgrei e cileni. Atti del XX Congresso Geografico Italiano, Roma, Societa' Geografica Italiana
Borgia A (1987) Shape and structure of Arenal volcano, Costa Rica. Abstract. Submitted to International Union of Geodesy and Geophysics XIX General Assembly
Borgia A, Linneman S, Spencer D, Morales LD, Brenez JA (1983) Dynamics of lava flow fronts, Arenal volcano, Costa Rica. J Volcanol Geotherm Res 19:303–329
Borgia A, Poore C (1983) New crater in Costa Rica. EOS, American Geophysical Union 64:450
Carr MJ, Stoiber RE (1977) Geologic setting of some destructive earthquakes in Central America. Geol Soc Am Bull 89:151–156
Carr MJ, Walker AJ Intra-eruption changes in compossition of some mafic to intermediate tephras in Central America, Journal of Volcanology and Geothermal Research (in press)
Chiesa S (1987) La mayor eruption pliniana del Volcan Arenal, Costa Rica. Revista Geologica de America Central, 6:25–41
Cigolini C, Borgia A (1979) Consideraciones sobre la viscosidad de la lava y la estructura de las coladas del Volcan Arenal. Costa Rica. Revista Geografica de America Central 11-12:131–140
Cigolini C, Bogliotti C (1984) Phase relationships and “silicate liquid immiscibility” in Arenal volcano lava flows, Costa Rica: preliminary studies. Atti della Accademia delle Scienze di torino 118:226–236
Cigolini C, Borgia A, Casertano C (1984) Intracrateric activity, aa-block lava, viscosity and flow dynamics: Arenal Volcano, Costa Rica. J Volcanol Geotherm Res 20:155–176
Cigolini C, Kudo AM (1987) Xenoliths in recent basaltic andesite flows from Arenal Volcano, Costa Rica: Inference on the composition of the lower crust. Contrib Mineral Petrol, 96:381–390
Crisp JA (1984) Rates of magma emplacement and volcanic output. Jorunal of Volcanology and Geothermal Research 20:177–211
Dengo G (1962) Tectonic-igneous sequence in Costa Rica. Petrologic Studies: a volume to honor A. F. Buddington. In: AEJ Engel, HL James, BF Leonard (eds) Geol Soc Am
Dengo G (1968) Estructura geologica, historia tectonica y morfologia de la America Central. Centre Regional de Ayuda Tecnica (AID), Mexico DF, Mexico
Feigenson MD, Carr MJ (1985) Determination of major, trace, and rare earth elements in rocks, using DCP-AES. Chem Geol 51:19–27
Fudali RR, Melson WG (1972) Ejecta velocities, magma chamber pressure, and kinetic associated with the 1968 eruption of Arenal volcano. Bull Volcanol 35:383–401
Holdridge LR, Poveda LJ (1975) Arboles de Costa Rica. Centro Cientifico Tropical, Costa Rica
Hollister LS, Crisp JA, Kulic CG, Mase W, Sisson VB (1984) Quantitative energy dispersive analysis of rock-forming silicates. In: AD Romig Jr, JI Goldstein (eds) Microbeam Analysis, San Franciso Press, pp 143–144
Malavassi E (1979) Geology and petrology of Arenal Volcano, Costa Rica. Thesis, University of Hawaii, USA, p 111
Malavassi V, Madrigal R (1970) Reconocimiento geologico de la Zona Norte de Costa Rica. Direccion de Geologia, Minas y Petrolio, Costa Rica. Informe Tecnico y Nota Geologica 9:38:12
Matsumoto T, Umana JE (1976) Informe sobre la eruption del Volcan Arenal occurrida el 17 de junio de 1975. Revista Geografica del Institute Panamericano de Geografia e Historia 5:229–315
Melson WG (1982) Alternation between acidic and basic magmas in major explosive eruptions of Arenal volcano, Costa Rica. Boletin de Vulcanologia, Universidad Nacional, Costa Rica. 14:65–74
Melson WG, Saenz R (1968) The 1968 eruption of Volcano Arenal: preliminary summary of field and laboratory studies. Smithsonian Center for Short-Lived Phenomena, Report 7-1968
Melson WG, Saenz R (1973) Volume energy and cyclicity of eruptions of Arenal Volcano, Costa Rica. Bull Volcanol 37:416–437
Melson WG, Barquero JH, Saenz RR, Fernandez E (1986) Eruptiones explosivas de importancia en volcanes de Costa Rica. Boletin de Vulcanologia, Escuela de Ciencias Geograficas, Universidad Nacional, Heredia, Costa Rica. 16:15–19
Mora S (1983) Una revision y actualizacion de la clasificacion morfotectonica de Costa Rica, segun la teoria de la tectonica de placas. Boletin de Vulcanologia, Costa Rica 13:18–36
Obando ALG (1986) Estratigrafia de la formacion Venado y rocas sobreyacentes (MiocenoReciente) provincia de Alajuela, Costa Rica. Rev Geol Centr 5:73–104
Reagan KM, Gill JB, Malavassi E (1987) Changes in magma composition at Arenal Volcano, Costa Rica, 1968-1985: Realtime monitoring of open-system differentiation. Bull Volcanol 49:415–434
Rose WI, Anderson AT, Woodruff LG, Bonis SB (1978) The October 1974 basaltic tephra from Fuego Volcano: description and history of the magma body. J Volcanol Geotherm Res 4:3–53
Saenz R (1977) Eruption del Volcan Arenal en el ano 1968. Revista Geografia de America Central, Costa Rica, 5– 6:149–188
Umana JE, Mainieri A, Alfonso P, De La Torre P, Laporte G (1973) Informe geologico e viabilidad, Proyecto Arenal. Open file rep, Departamento de Geologia, ICE
Van der Bilt H, Paniagua S, Avila G (1976) Informe de la actividad del Volcan Arenal iniciada el 17 de junio de 1975. Revista Geografica del Instituto Panamericano de Geografia e Historia, Mexico. 5:295–298
Wadge G (1984) The magma budget of Volcan Arenal, Costa Rica, from 1968 to 1980. J Volcanol Geotherm Res 19:281–302
Walker JA, Carr MJ (1986) Compositional variations caused by phenocryst sorting at Cerro Negro volcano, Nicaragua. Geol Soc Am Bull 97:1156–1162
Williams H, McBirney A (1979) Volcanology. Freeman, Cooper & Co, San Francisco, p 397
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Borgia, A., Poore, C., Carr, M.J. et al. Structural, stratigraphic, and petrologic aspects of the Arenal-Chato volcanic system, Costa Rica: Evolution of a young stratovolcanic complex. Bull Volcanol 50, 86–105 (1988). https://doi.org/10.1007/BF01275171
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF01275171