Phengite-Based Chronology of K- and Ba-Rich Fluid Flow in Two Paleosubduction Zones
E. J. Catlos,1*
S. S. Sorensen2
Subduction recycles aqueous fluids from slab and sediment to the
mantle. Subduction zones are long-lived, but time scales for fluid-rock
interaction within subduction complexes are uncertain. Large-ion
lithophile elements (potassium and barium) were added to
eclogite (subducted basalt) during high pressure/temperature metamorphism via phengite crystallization from subduction zone fluids.
Phengite grains from eclogite blocks and their metasomatic selvages
yielded 40Ar/39Ar ages across grains and
between samples that indicate 25 and 60 million years of fluid-rock
interaction in the Samana Complex, Dominican Republic, and the
Franciscan Complex, California, respectively.
1 School of Geology, Oklahoma State University,
105 Noble Research Center, Stillwater, OK 74078, USA.
2 Department of Mineral Sciences, NHB-119, National
Museum of Natural History, Smithsonian Institution, Washington, DC
20560-0119, USA.
*
To whom correspondence should be addressed. E-mail:
catlos{at}okstate.edu
