REVISED “SEPM” MESOZOIC-CENOZOIC SEQUENCE CHRONOSTRATIGRAPHIC CHARTS

In 1998, an extensive “Mesozoic and Cenozoic Sequence Chronostratigraphic Framework of European Basins”chart series (Hardenbol et al.) was published with SEPM Special Publication 60 (de Graciansky et al., ed.). This compilation by diverse experts for bio-, magneto-, chemo- and sequence-stratigraphy was calibrated to the geologic time scales of 1995. Depositional sequences were systematically labeled by stage-number designations-- for example, “Ser 4” is the fourth sequence in stratigraphic succession within the Serravallian stage of Miocene.

Aspects of the numerical ages and the inter-calibrated chronostratigraphic scales had gradually become outdated during the following decade. Therefore, we recalibrated these chronostratigraphic and sequence stratigraphy charts to Geologic Time Scale 2004 (Gradstein et al., 2004, Cambridge Univ. Press). The updated charts will be posted at the websites of the International Commission on Stratigraphy (ICS; www.stratigraphy.org), CHRONOS (www.chronos.org) and SEPM.

The recalibration process raised other issues, such as an apparent systematic offset of some interpreted sequences between Tethyan-carbonate and Boreal-clastic facies.

As part of this revision process, we created a JAVA package for visualization and accessing additional information on calibration relationships, biostratigraphic datum and zonal definitions, and other correlations. A user of this JAVA package specifies the time interval, chooses which columns to plot, and assigns the vertical scale (cm per million years) and other display parameters. In addition to producing an optimized screen view with “hot-cells” opening windows to additional information, the software generates a scalable-vector graphics (SVG) file for printing posters or for direct importation into popular graphics programs (e.g., Adobe Illustrator). Revising control ages or stratigraphic relationships in the underlying database of relationships will adjust ages of the other dependent stratigraphic scales, and the JAVA package will generate revised charts. Upon release of the JAVA visualization tool and the Mesozoic-Cenozoic database, we hope that public commentary and involvement will enable improved global and regional stratigraphic scales for Earth history.