SEA-LEVEL CHANGES AROUND THE CENOMANIAN-TURONIAN BOUNDARY

The stratigraphical position of widespread hardgrounds in chalk successions mark the time of regressive troughs of sea-level. Using this technique it has been possible to chart the dates of regressive troughs through the Middle Cenomanian to Late Turonian in north-west Europe, and these dates are probably correct for other regions free from tectonic interference. Although there was a transgressive peak during the later half of the Zone of Metoicoceras geslinianum in the Late Cenomanian, the great eustatic high that has sometimes been quoted close to the Cenomanian-Turonian boundary, or in the early Turonian, was actually appreciably later, early in the Zone of Collignoniceras woollgari of the Middle Turonian. © 1993 Academic Press. All rights reserved.