Geochemical and geothermal evidence for fluid migration in the Barbados Accretionary Prism (ODP leg 110)

Abstract

Measured geochemical and geothermal effects of fluid migration in the northern Barbados accretionary prism indicate that: (1) fluid flows laterally along low‐angle active faults; (2) the entire length of the Leg 110 transect is a fluid discharge zone; (3) migration results in heating of sediments across the transect but most strongly at the deformation front; and (4) migration results in dilution of pore water‐Cl and 18O enrichment more in the arcward than the seaward side of the prism, suggesting that the Cl‐poor, 18O‐rich fluids that intrude the prism are derived from smectiteillite reactions occurring arcward. These conclusions have strengthened those derived from the initial appraisal of shipboard data, modified ideas about where fluids are heated most and where the geochemistry is strongly altered, and provided new ideas about the sources of fluids and their relative contributions.