ROAD-TESTING THE PALEOGENE GLOBAL STRATOTYPE SECTIONS AND POINTS (GSSPS): THE YPRESIAN-LUTETIAN TRANSITION IN THE GULF COASTAL PLAIN AND THE NORTHERN CARIBBEAN

There are nine ratified or proposed GSSPs in the Paleogene designed to standardize definitions and facilitate correlation of the stages. All of the ratified and candidate sections containing the GSSPs were formed in deep water environments and many of the guide events used for correlation are most reliable in oceanic settings. Recognizing the precise boundaries defined in the Paleogene GSSPs is a challenge in the unconformity bounded sequences of the Gulf Coastal Plain and the sediment dominated sections in western Cuba and Jamaica. An example of one such problematic interval in the Gulf and Caribbean is the Ypresian-Lutetian transition.

The Lutetian GSSP is in the Gorrondatxe section of northern Spain. The primary guide event is the First Appearance Datum (FAD) of the calcareous nannofossil Blackites inflatus. The GSSP occurs just below the lowest occurrence (LO) of the nannofossil Nanotetrina cristata and just above the LO of the planktonic foraminiferan Turborotalia frontosa , the nominate taxon of biosubzone E7b. In the Gulf Coastal Plain, the Ypresian-Lutetian transition is represented by the significant unconformity associated with the base of Claiborne Group. In the Avenida de los Presidentes section in Havana, Cuba, the key nannofossils have not been described but abundant planktonic foraminifera including T. frontosa make an approximation of the Ypresian-Lutetian boundary possible. The Rio Sambre section in Jamaica has abundant nannofossils and planktonic foraminifera but none of the guide taxa are present making precise placement of the boundary difficult. The Ypresian-Lutetian section in ODP Site 998 on the Cayman Rise consists of pelagic limestones making nannofossil studies difficult. Thin-sections do reveal abundant planktonic foraminifera allowing a correlation to the Gorrondatxe GSSP.

Despite these challenges, the GSSP concept has proven useful in studying the Ypresian-Lutetian interval in the Gulf and Caribbean region. The Gorrondatxe GSSP has provided stability in the definition of the Lutetian, a concept which had slightly different meanings in Jamaica, Cuba, and the Gulf Coastal Plain. While the Gorrondatxe GSSP may not permit a precise boundary to be identified in all sections in the region, it does allow reliable age determinations to be made for the early and middle Eocene rocks present.