Enhanced coastal paleoproductivity and nutrient supply in Upper Egypt during the Paleocene/Eocene Thermal Maximum (PETM): Mineralogical and geochemical evidence

We have analyzed the geochemistry and mineralogy of the five characteristic beds that constitute the Dababiya Quarry Member (DQM) recovered from the Dababiya Quarry Core located near the Global Stratotype Section and Point (GSSP) for the base of the Eocene. Well developed in Upper Egypt, these beds are known to record the isotopic and biotic signatures of the Paleocene/Eocene thermal maximum (PETM). We have extracted the mineral phases from these beds (representing a total thickness of 2.35 m) and compared them with those of the encasing shales through qualitative and semi-quantitative SEM analysis using EDX technology. Total organic carbon was determined using the titrimetric method. Major and trace elements were analyzed using an inductively coupled plasma-optical emission spectrometer, and enrichment factors were established relative to Al content. We discuss the significance of our data with regard to basaltic volcanism and cometary impact, for neither of which we find support. In agreement with other studies, our data indicate very high biological productivity during the deposition of the DQM. This may be related to upwelling and/or increased nutrient supply, the latter because of an enhanced hydrologic cycle. (C) 2011 Elsevier B.V. All rights reserved.