Figure 4. Late Paleocene thermal maximum (LPTM) as observed in a variety of downhole measurements at Site 999. The log response at 975.5 mbsf is consistent with the recovered claystone interval that contains the negative 13C excursion marking the LPTM. These data indicate an abrupt and distinct difference in physical/chemical properties that extend for tens of meters above and below the LPTM. The variation in CaCO3 concentration as derived from measurements made with the downhole geochemical tool compares well with that of Ca concentration measured with the XRF core scanner (thick line), and both indicate the dramatic decrease in carbonate at the LPTM.