Late Quaternary variability of sedimentary nitrogen isotopes in the eastern South Pacific Ocean

• Published in: Paleoceanography
• Main Authors: De Pol-Holz, Ricardo, Ulloa, Osvaldo, Lamy, Frank, Dezileau, Laurent, Sabatier, Pierre, Hebbeln, Dierk
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Geophysical Union 2007
• Subjects: Eastern South Pacific; Denitrification; Late Quaternary; Pacific; Patagonia; Ice Sheet
• Online Access: https://hdl.handle.net/1912/3446

Author Posting. © American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 22 (2007): PA2207, doi:10.1029/2006PA001308. We present high-resolution bulk sedimentary δ 15N data from the southern edge of the present-day oxygen minimum zone of the eastern South Pacific. The record is interpreted as representing changes in water column nitrogen removal during the last 70,000 years. We found significant fluctuations in the isotopic signal that suggest major reorganizations of the oxygen minimum zone at millennial timescales. These fluctuations were not related to other millennial-scale changes like the Northern Hemisphere's Dansgaard-Oeschger climate swings or local changes in primary productivity, so appear to be dictated by the Southern Hemisphere's climate rhythm. This is preliminarily corroborated by an overall agreement between our δ 15N data and the sedimentary proxy of ice sheet dynamics in Patagonia, which is in turn correlated with surface water properties at the midlatitude subduction region of the eastern South Pacific intermediate waters. Finally, potential implications on late Quaternary changes in atmospheric CO2 concentrations are discussed. This work was funded by the Chilean National Commission for Scientific and Technological Research (CONICYT) through the FONDAP Program and by the Fundacio´n Andes. Additional support was provided by the German Ministry for Science and Education through the PUCK project. R.D.P.H. was supported by graduate fellowships coming from Fundacio´n Andes, CONICYT, and MECESUP/UCO2002.