HR: 0830h
AN: V31C-0939    [PDF]
TI: The Geochemical Evolution of Arenal Volcano, Costa Rica
AU: * Bolge, L L
EM: lbolge@rci.rutgers.edu
AF: Rutgers University, 610 Taylor Rd, Piscataway, NJ 08854 United States
AU: Carr, M J
EM: carr@fas.rutgers.edu
AF: Rutgers University, 610 Taylor Rd, Piscataway, NJ 08854 United States
AU: Feigenson, M D
EM: feigy@rci.rutgers.edu
AF: Rutgers University, 610 Taylor Rd, Piscataway, NJ 08854 United States
AU: Alvarado I., G E
EM: GAlvaradoI@ice.go.cr
AF: Instituto Costarricense de Electricidad, Apdo. 10032-1000, San Jose, 34020 Costa Rica
AB: Arenal is a small stratovolcano located in northwestern Costa Rica, along the Central American volcanic front. It is the youngest and most active volcano in Costa Rica. Field studies by Soto et al. (1996) have discovered over twenty distinct tephra layers and several lavas. This sequence spans approximately 7000 years. The geochemistry of these tephras and lavas show many variations in La/Yb, Zr/Hf, and Nb/Ta indicating changes in percent melting over time. Specifically, the percent of melting appears to increase for the first 4000 years, then decrease for the last 3000 years. Trace element ratios that track the subducted slab signal, such as Ba/La, U/Th and Pb/Ce correlate positively with the apparent percent of melting. These slab signal indicators increase during the first 4000 years of Arenal's history and then decrease for the last 3000 years. Because of Arenal's high rate of eruption and the comprehensive sampling of major units, it is possible to show small temporal changes in the amount of flux melting in the mantle wedge beneath Arenal.
DE: 8400 VOLCANOLOGY
DE: 8439 Physics and chemistry of magma bodies
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting