Evolution of the Acipayam (Denizli, Turkey) rodingites

Numerous diabase and gabbro dikes intrude the Lycian peridotite thrust shee t of southwestern Turkey. Some of the dikes axe rodingitized and the host h arzburgite is serpentinized. The present study demonstrates that the major episodes of serpentinization (of harzburgite) and rodingitization (of dikes ) predated the obduction of the Lycian peridotite thrust sheet. Hydrogrossu lar veins, which represent the major event of calcium metasomatism in the d ikes, are locally fractured, fragmented, and offset. High-field-strength-el ement concentrations and Ta/Yb-Th/Yb ratios in the mafic rocks suggest that the dikes were originally emplaced in an island-are environment; thus, the y must have been transported to their current location. Fluid-inclusion microthermometry obtained on primary fluid inclusions in hy drogrossulars indicates that the fluid involved in rodingitization and cont emporaneous serpentinization was moderately saline (8 equiv. wt% NaCl) and within the range of 250 degrees -450 degreesC. The above salinity and tempe rature are consistent with microthermometric measurements obtained from rod ingite minerals worldwide. It is apparent from our study that rodingite geochemistry and mineralogy pr ovide valuable information on the tectonic and metamorphic evolution of a r egion. Trace-element and REE geochemistry can define the tectonic setting O f dikes, detailed mineralogy of the dikes and host serpentinite provides in formation on the relative timing of serpentinization and contemporaneous ro dingitization, and fluid-inclusion microthermometry provides information on the temperature and composition of the Ca-rich metamorphic fluids.