MODEL FOR THE GENESIS OF YOUNG CONTINENTAL-ARC SHOSHONITES IN THE TALAMANCA CORDILLERA, COSTA RICA
Alfaro, Aristides Jose
Aristides José Alfaro Gálvez investigated the Late Cenozoic magmatism of the Talamanca Cordillera, Southern Central America. Six to five Ma continental-arc shoshonites and other high-K rocks crop out among the summits of that region. Their trace element composition (Sr~1700 ppm at Rb~120 ppm concentrations) suggests a genesis related to subduction processes rather than lower crustal melting. This work integrates Monte Carlo simulations of trace element geochemistry and isotopic evidence in order to explain the origin of these highly enriched continental arc igneous rocks. The main conclusion is that the trace element budget of the Talamanca arc rocks requires the input of an incompatible element-enriched component, similar in composition to the Cocos Island Province (Pacific Ocean), as a result of slab melting of subducted seamounts.
Central America; Continental crust; Shoshonite; Slab melting; Subduction; Talamanca cordillera
White, Bill; Keranen, Kade
M.S., Geological Sciences
Master of Science
dissertation or thesis