North-Central Section - 50th Annual Meeting - 2016

Paper No. 6-7
Presentation Time: 10:20 AM


DAMMANN, Isabel D.R., Geology, Lawrence University, 711 E. Boldt Way, Appleton, WI 54911 and MILLIKIN, Alexie, Geology, Colorado College, Colorado Springs, CO 80903,

The Early­-Late Paleocene Event (ELPE) is a short­lived hyperthermal recorded in pelagic sediments that crop out northwest of Gubbio, Italy, and makes up the latter portion and climax of a 250 kyr­long event of environmental disruption called the Selandian­-Thanetian Transition Event (STTE). The STTE is marked in pelagic sediments by gradual decrease in carbonate content, increase in magnetic susceptibility, and negative δ13C shift. We studied a stratigraphic section of the Scaglia Rossa R3 formation that spans the STTE and ELPE, 16­ to 24 meters above the K/Pg boundary along the Contessa Highway. We astronomically tuned the section using magnetic susceptibility (MS) data from Coccioni et al. (in prep.), and initially assigned two distinct sedimentation rates before and after the ELPE based on evidence from our stratigraphic-domain spectral analysis. Tie points were used to match short eccentricity cycles in the magnetic susceptibility data to calculated orbital forcing in order to derive a changing sedimentation rate. A variable sedimentation rate described our section well and yielded frequency peaks consistent with short eccentricity and precession cycles. The changing sedimentation rate appears to be consistent with a longer-term cooling trend from 60.1 to 58.3 Ma in the Paleocene rather than short term carbonate dissolution during hyperthermals. In our solution, based on Laskar et al. 2004, the ELPE is centered at 58.75 Ma, which is in the range of the previous estimate. The ELPE occurs at a short eccentricity maximum and a long eccentricity minimum, providing evidence that the event is not astronomically forced.