Architectural and Tectonic Control on the Segmentation of the Central American Volcanic Arc

Central America has a rich mix of conditions that allow comparisons of different natural experiments in the generation of arc magmas within the relatively short length of the margin. The shape of the volcanic front and this margin's architecture derive from the assemblage of exotic continental and oceanic crustal slivers, and later modification by volcanism and tectonic activity. Active tectonics of the Cocos-Caribbean plate boundary are strongly influenced by oblique subduction, resulting in a narrow volcanic front segmented by right steps occurring at similar to 150-km intervals. The largest volcanic centers are located where depths to the slab are similar to 90-110 km. Volcanoes that develop above deeper sections of the subducting slab are less voluminous and better record source geochemical heterogeneity. Extreme variations in isotopic and trace element ratios are derived from different components of the subducted oceanic lithosphere. However, the extent that volcanoes sample these signatures is also influenced by lithospheric structures that control the arc segmentation. The architecture of Central America derives from the assemblage of exotic continental and oceanic crustal slivers modified by arc magmatism and tectonic processes. Active tectonics in Central America are controlled by oblique subduction. The lithospheric architecture and tectonics define the segmentation of the volcanic front, and thus the depth to the slab below a volcanic center. The composition of the subducted material is the main control of the along arc geochemical variations observed in Central American volcanoes. Geochemical heterogeneity in each segment is highlighted by extreme compositions representing the smaller centers with variations up to 65% of the total observed range.

Automated summary

Central America provides a rich setting for studying arc magmatism, with a narrow volcanic front segmented by right steps at 150-km intervals, influenced by oblique subduction of the Cocos-Caribbean plate boundary. Volcanic centers located above depths of 90-110 km are larger and exhibit source geochemical heterogeneity. The composition of subducted oceanic lithosphere controls geochemical variations in Central American volcanoes, while lithospheric structures influence arc segmentation.