BIOSTRATIGRAPHY, MINERALOGY AND GEOCHEMISTRY OF THE TRABAKUA PASS ANDERMUA SECTIONS IN SPAIN - PALEOCENE-EOCENE TRANSITION

Isotopic, geochemical and bulk mineralogical analyses in the Trabakua and Ermua sections, Basque Basin, reveal major changes across the Pale ocene-Eocene transition. Expanded sedimentary records exhibit a gradua l decrease of 1.0 parts per thousand in delta(13)C values in the lower part of Zone P5 followed by a more rapid 3 parts per thousand negativ e excursion. The 3 parts per thousand delta(13)C excursion is associat ed with an abrupt decrease in carbonate sedimentation, increased detri tal flux and decreased grain size which suggest changes in marine/atmo spheric currents and/or size and structure of the ocean carbon reservo ir. The clays recognized at Trabakua record a deep burial diagenesis a s indicated by two generations of chlorite, the presence of mixed-laye rs chlorite-smectite and illite-smectite, the absence of smectite and the near absence of kaolinite. The very low delta(18)O values (<-3.5 p arts per thousand) throughout the Trabakua and Ermua sections reflect diagenetic alteration rather than paleotemperatures. Because of deep b urial diagenesis and very poorly preserved microfossils, the Trabakua Pass and Ermua sections are not optimal potential stratotypes for the Paleocene-Eocene boundary.