Cross-arc geochemical variations in volcanic fields in Honduras C.A.: progressive changes in source with distance from the volcanic front |
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| Authors: | Lina C Patino Michael J Carr Mark D Feigenson |
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| Institution: | (1) Geological Sciences, Rutgers University, New Brunswick, NJ 08903, USA, US |
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| Abstract: | A geochemical traverse across Honduras reveals the heterogeneity of the mantle underneath Central America. Alkali basalts
from Lake Yojoa (170 km behind the front) have low 87Sr/86Sr but high La/Yb, and elevated incompatible trace element abundances, consistent with derivation from a normal mid-ocean
ridge basalt source mantle via low degrees of melting. These lavas lack evidence for an enriched source thought to be intermingled
with normal mid-ocean ridge basalt source mantle beneath most of Central America. The amplitude of the subducted slab signature
decreases smoothly with distance from the volcanic front. Lavas from Zacate Grande, the area nearest to the volcanic front
(17 km behind the arc), display large ion lithophile element enrichment and high field strength element depletion indicating
the involvement of subducted material in magma genesis. Components of subducted material are not evident in lavas from Lake
Yojoa, the area furthest from the arc. Basalts and basaltic andesites from Tegucigalpa, 102 km behind the volcanic front,
are geochemically intermediate between those of Lake Yojoa and Zacate Grande. The lavas from Tegucigalpa show a decreased
influence of the subduction component, and are affected by assimilation-fractional crystallization processes at shallow depths.
The gradual decrease in the subducted component from the volcanic front to Zacate Grande, Tegucigalpa and finally Lake Yojoa
contrasts with the abrupt decrease documented for southeast Guatemala, the only other area in Central America where a cross-arc
transect has been studied.
Received: 1 July 1995 / Accepted: 16 July 1997 |
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