The present work offers the first biostratigraphic calibration based on calcareous nannoplankton of the
three evaporitic assemblages in the Rio Chicamo section. The A. primus FAD is registered at the upper part
of the Sanel marls, above the lower gypsum, and bellow the Tale gypsum. The A. delicatus FAD, and the A.
amplificus FAD occurs in the lower and upper part of the Chicamo Cycles, respectively, which allow to
calibrate the Chicamo Cycles reversal as the chron C3Ar. The Tortonian/Messinian boundary is found at
the Tale gypsu
