BIOSTRATIGRAPHIC EVENTS AT THE BARREMIAN APTIAN BOUNDARY IN THE BETICCORDILLERA, SOUTHERN SPAIN/

This paper presents an analysis of the vertical distribution of ammoni tes and calcareous nannofossils throughout the uppermost Barremian-low ermost Aptian interval of pelagic sections in the External Zones of th e Eerie Cordillera (southern Spain). We were able to identify all the standard ammonite zones in this interval and have established for the first time a direct calibration of calcareous nannofossil events again st the ammonite zonation. The results confirm that the Baaemian/Aptian boundary, defined by the first appearance of Deshayesites, does not c oincide with any other biostratigraphic event. Nonetheless, the sequen ce of events recorded in the studied sections provides alternative cri teria on which to characterize this boundary with reasonable accuracy. A new nannofossil species (Micrantholithus stellatus sp. nov.) is als o described. (C) 1997 Academic Press Limited.