Decadal to Orbital Links Between Climate, Productivity, and Denitrification on the Peru Margin; Do Models of Persistent EL Ni±o or La Ni±a Conditions Apply?

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This is a pilot study to determine whether a reliable chronology can be developed via alkenone dating and magnetic paleointensity for sediment cores from the Peru margin. If so, then follow on studies will investigate the denitrification zone of the Peru margin, its possible links with productivity and El Nino/ La Nina cycles, and the extent to which suboxic conditions in the water column, leadng to denitification, are correlated with rapid climate change events on decadal to orbital time scales for the last 60 k years. The study will utilize scores drilled on ODP Leg 112, and eventually will be a multiproxy study of several cores in a variety of water depths. Most of the cores contain only a small carbonate fraction and some of the cores are laminated. For cores containing forms, high resolution chronologies will be established with foram 14 C and S 18 O and for those without forams a combination of geomagnetic paleointensity, alkenone 14C, and optical methods will be used. In this pilot study, two cores, one with limited foram abundances and one with no forams, will be studied to establish chronologies.