HR: 1340h
AN: V13B-1483    [Abstracts]
TI: Geochemistry of Concepcion and Maderas Volcanoes, Nicaragua, Central America
AU: * Lindsay, F N
EM: flindsay@rci.rutgers.edu
AF: Rutgers University, Wright Labs Geological Sciences 610 Taylor Rd, Piscataway, NJ 08854 United States
AU: Bolge, L L
EM: bolge@bu.edu
AF: Boston University, Department of Earth Sciences 685 Commonwealth Ave., Boston, MA 02215 United States
AU: Carr, M J
EM: carr@rci.rutgers.edu
AF: Rutgers University, Wright Labs Geological Sciences 610 Taylor Rd, Piscataway, NJ 08854 United States
AU: Feigenson, M D
EM: feigy@rci.rutgers.edu
AF: Rutgers University, Wright Labs Geological Sciences 610 Taylor Rd, Piscataway, NJ 08854 United States
AB: The occurrence of geochemical zoning along the Central American volcanic arc is due primarily to changes in mantle composition and both the composition and amount of incorporated slab components. The maximum slab signal, represented by the ratio of Ba/La, occurs in the Nicaraguan volcano Telica and decreases to both the northwest and southeast. Whereas continuous geochemical coverage between El Salvador and Nicaragua suggests that the transition is gradual, a gap in volcanic geochemical analyses between Nicaraguan and Costa Rican volcanoes hinders any conclusion as to whether the decrease is gradual here as well, or more abrupt. To this end, we analyze newly collected volcanic lavas from Isla de Ometepe in Lago de Nicaragua and northern Costa Rica using XRF and HR- ICP- MS techniques to quantify major oxides and trace elements. The island consists of two volcanoes: Concepcion and Maderas. Concepcion is presently active and records two periods of lava flows, one recent and one prehistoric. Here, our work on lavas from the eastern side of the island complements the recent work by Benjamin van Wyk de Vries on western tephra. Maderas, while not historically active, has long been a private coffee plantation granting public access only recently. These analyses will mark the first samples of this volcano within the geological community.
DE: 8499 General or miscellaneous
DE: 1099 General or miscellaneous
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting