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Guatemala jadeitites and albitites were formed by deuterium-rich serpentinizing fluids deep within a subduction zone

January 1, 1999

Jadeitites and albitites from the Motagua Valley, Guatemala, are high-pressure-low-temperature metasomatic rocks that occur as tectonic inclusions in serpentinite-matrix melange. Metasomatism was driven by a fluid with a ??18OH2O value of 6???, and a ??DH2O value that is high in comparison with metamorphic fluids at other high-pressure-low-temperature localities of similar grade. We infer that the fluid was originally seawater that was entrained during subduction either as mineral-bound H2O or as free pore waters. The fluid drove serpentinization reactions in ultramafic rocks, possibly leading to deuterium enrichment of H2O, prior to forming the Jadeitites and albitites at a depth of 29 ?? 11 km. There are isotopic and fluid-inclusion similarities to rodingites, which are Ca-rich metasomatites found at other serpentinite localities. Our results suggest that the serpentinization process, whether it occurs within subduction zones or on the flanks of oceanic spreading ridges, may produce residual fluids that are H2O rich, have 1-8 wt% equivalent NaCl, and have high, perhaps sea water-like, ??D values.

Citation Information

Publication Year 1999
Title Guatemala jadeitites and albitites were formed by deuterium-rich serpentinizing fluids deep within a subduction zone
DOI
Authors C.A. Johnson, G.E. Harlow
Publication Type Article
Publication Subtype Journal Article
Series Title Geology
Series Number
Index ID 70021422
Record Source USGS Publications Warehouse
USGS Organization