Milankovitch-scale cycles can be recognized in high-resolution
delta(13)C, delta(18)O, Sr/Ca, mineralogical, and magnetic
susceptibility data in hemipelagic sediments that span the last 700 kyr
of the Maastrichtian at Elles, Tunisia. Oxygen isotope data reveal three
cool periods between 65.50 and 65.55 Ma (21.5-23.5 m), 65.26 and 65.33
Ma (8-11 in), and 65.04 and 65.12 Ma (1.5-4 m), and three warm periods
between 65.33 and 65.38 Ma (12-16 m), 65.12 and 65.26 Ma (4-8 in), and
65.00 and 65.04 Ma (0-1.5 m). The cool periods are characterized by
small surface-to-deep temperature gradients that reflect intensive
mixing of the water column. The surface-to-deep Sr/Ca gradient generally
correlates with the oscillating AT trend (temperature difference between
surface and bottom waters). The carbon isotope composition of planktonic
foraminifera indicates a continuous decrease in surface bioproductivity
during Late Maastrichtian. Decreasing Delta(13)C values (difference
between the delta(13)C values of surface and bottom dwelling
foraminifera) and the carbon isotope ratios of the planktonic species at
the onset of gradual warming at 65.50 Ma reflect a reduction in surface
productivity as a result of decreased upwelling that accompanied global
warming and possibly increased atmospheric pCO(2), related to Deccan
Trap volcanism. Time series analysis applied to magnetic susceptibility,
delta(18)O, and Sr/Ca data identifies the 20 kyr precession, 40 kyr
obliquity, and 100 kyr eccentricity Milankovich cycles. (C) 2003
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