Annual Report 2008 of the Rupelian/Chattian Boundary Stratotype Working Group

The paper on “Integrated stratigraphy of the Oligocene pelagic sequence in the Umbria-Marche basin (Northeastern Apennines, Italy): A potential GSSP for the Rupelian/Chattian boundary” by Coccioni and others, was finally published on the Geological Society of America Bulletin in April 2008. The paper synthetises the detailed biostratigraphic, magnetostratigraphic, and chemostratigraphic studies, along with geochronologic results from several biotite-rich volcaniclastic layers, which provide the means for an accurate and precise radiometric calibration of the Oligocene time scale. The interpolated ages for the Rupelian/Chattian stage boundary, located in the upper half of Chron 10n at meter level 188 in the Monte Cagnero section, and corresponding to the O4/O5 planktonic foraminiferal zonal boundary, are 28.36 Ma (paleomagnetic interpolation), 28.27 ± 0.1 Ma (direct radioisotopic dating), and 27.99 Ma (astrochronological interpolation). These ages appear to be slightly younger than those reported in recent chronostratigraphic time scale compilations. At the end of the article the authors designated the Monte Cagnero (MCA) section, out of the three sections studied, as the best GSSP candidate for the Rupelian/Chattian boundary. The formal proposal to be submitted to the Subcommission is in preparation.
Coccioni R., Marsili A., Montanari A., and Others, 2008. Integrated stratigraphy of the Oligocene pelagic sequence in the Umbria-Marche basin (northeastern Apennines, Italy): A potential Global Stratotype Section and Point (GSSP) for the Rupelian/Chattian boundary. GSA Bulletin, v. 120; no. 3/4, p. 487–511, 17 figures, 4 tables. doi: 10.1130/B25988.1.

Report by Isabella Premoli Silva, Chairwoman