Open AccessChlorine isotope variations along the Central American volcanic front and back arc
Author(s) -
Barnes J. D.,
Sharp Z. D.,
Fischer T. P.,
Hilton D. R.,
Carr M. J.
Publication year - 2009
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1029/2009gc002587
Subject(s) - geology , tephra , volcano , front (military) , geochemistry , lava , volcanic rock , mantle (geology) , oceanography
Volcanic outputs (ash, tephra, and lava samples) of 23 volcanic centers from the volcanic front, secondary front, and back arc in Central America were analyzed for their δ 37 Cl values with the goal of using chlorine isotopes as a tracer of fluids sourced from the subducting Cocos slab. δ 37 Cl values range from −2.6 to +3.0‰ with systematic variations along the length of the front. Values from the northernmost (Guatemala and El Salvador) and southernmost (Costa Rica) ends of the front have mantle‐like signatures. In contrast, δ 37 Cl values are both positive and negative in the center of the front (Nicaragua), implying a sediment and/or serpentinite‐derived component. Geophysical observations are consistent with extensive hydration of the Cocos plate offshore of Nicaragua, in support of a serpentinite‐derived fluid source. Fluids from dehydrating serpentinites may also incorporate Cl from overlying sediments, resulting in a multiple‐source chlorine signature.