Stable isotope geochemistry of Quaternary calcretes in the Mersin area, southern Turkey - A comparison and implications for their origin

In the Mersin area, Quaternary calcretes are widespread, and occurred in a variety of forms, as namely powdery, nodular, tubular, fracture-infill, laminar crust, hard laminated crust (hardpan), pisolithic crust. They are predominantly calcite, and small amount of palygorskite associated with them as a minor component. Calcite delta O-18 and delta C-13 values of the calcretes vary from -4.31 to -6.82 and from -6.03 to -9.65 parts per thousand PDB, respectively. These values are consistent with values of pedogenic calcretes reported in literature from worldwide sites. The oxygen isotope values indicate formation under the influence of meteoric water at estimated temperatures from 25 to 32 degrees C. The carbon isotope values are typical for pedogenic calcretes, reflecting development under the C3-dominated vegetation cover and semiarid or seasonally arid climatic conditions. (C) 2011 Elsevier GmbH. All rights reserved.