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

• Published in: Paleoceanography
• Main Authors: De Pol-Holz, R., Ulloa, O., Lamy, F., Dezileau, Laurent, Sabatier, Pierre, Hebbeln, D.
• Other Authors: Departamento de Oceanografía Concepción, Universidad de Concepción Chile, GeoForschungsZentrum - Helmholtz-Zentrum Potsdam (GFZ), Géosciences Montpellier, Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Université des Antilles (UA)-Centre National de la Recherche Scientifique (CNRS), Fachbereich Geowissenschaften Bremen, Universität Bremen
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2007
• Subjects: eastern-south Pacific; denitrification; ate quaternary; [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces; environment; [SDE.MCG]Environmental Sciences/Global Changes; [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; Pacific; Patagonia; Ice Sheet
• Online Access: https://hal.archives-ouvertes.fr/hal-00407260; https://hal.archives-ouvertes.fr/hal-00407260/document; https://hal.archives-ouvertes.fr/hal-00407260/file/2006PA001308.pdf; https://doi.org/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.