PP037-0010
The intercalibration of astrochronological data with composite sections produced by constrained optimization (CONOP): A case study from Neogene strata in the Southern Ocean
Monday, 14 December 2020
Poster
Nicholas Benetti Sullivan1, Stephen Richard Meyers2, Peter Sadler3, Georgia R. Grant4, Richard H Levy4, Robert M Mckay5 and James S. Crampton5, (1)University of Wisconsin Madison, Madison, WI, United States, (2)Univ. of Wisconsin - Madison, Geoscience, Madison, WI, United States, (3)University of California Davis, Department of Earth Sciences, Davis, CA, United States, (4)GNS Science, Lower Hutt, New Zealand, (5)Victoria University of Wellington, Wellington, New Zealand
Abstract:
The integration of deep-time paleoceanographic records from the Southern Ocean provides a crucial context for the future of our warming planet. However, assembling and compositing a complete record is difficult, owing to the technical challenges of drilling in the high southern latitudes, as well as the incompleteness of a stratigraphic record repeatedly scoured by an advancing ice sheet. Although recent studies have leveraged the regional synthesis power of constrained optimization (CONOP), composite histories built by this method can be hard to calibrate temporally, owing to a paucity of radioisotopic tie points in the sedimentary record.
To improve the geochronological resolution of composite histories constructed by CONOP, we have developed a series of floating astrochronologies from the Miocene, Pliocene, and Pleistocene, using records generated by international drilling initiatives (IODP, ODP, ANDRILL) in both proximal and distal sections. Intervals of astrochronological significance have been added to the CONOP database as shrink-to-fit horizons (“clamps”) and correlated into the composite section. These floating astrochronologies were then anchored to adjacent geochronological tie points using a new Monte Carlo algorithm. The resulting astrochronologically-constrained composite reduces the temporal uncertainty of key transitions in the history of the Southern Ocean, and can be used to refine the age of important biotic and oceanographic events.
