An Atlantic lead over Pacific deep-water change across Termination I: implications for the application of the marine isotope stage stratigraphy.

• Published in: Quaternary Science Reviews
• Main Authors: Skinner, L. C., Shackleton, N. J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2005
• Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems; Pacific; Northeast Atlantic
• Online Access: http://eprints.esc.cam.ac.uk/1830/; http://eprints.esc.cam.ac.uk/1830/1/An_Atlantic_lead_-_Skinner.pdf; https://doi.org/10.1016/j.quascirev.2004.11.008

Globally synchronous changes in glacioeustatic sea-level provide a particularly useful stratigraphic reference in the study of glacial–interglacial climate change, and form the basis for the marine isotope stage (MIS) system, which posits a dominant glacioeustatic signal in benthic foraminferal d18O. However, benthic d18O strictly does not represent a pure sea-level record, and it is shown here that, due to local changes in deep-water hydrography, the MIS 2/1 boundary (i.e. benthic d18O change) occurred 4000 years later in the deepeastern equatorial Pacific than in the deepNortheast Atlantic. This discrepancy is too large to be attributed entirely to the Pacific lag that may be expected due to the mixing time of the ocean basins. Instead, multiple proxies (including benthic foraminiferal Mg/Ca) suggest that the large offset in benthic d18O most probably resulted from a late rise in deep-water temperature at the Pacific site and a series of coupled deep-water temperature and d18O changes at the Northeast Atlantic site. These findings have important implications for the application of the MIS stratigraphy and the interpretation of benthic d18O records in general, as they show that benthic d18O fluctuations and MIS boundaries from different hydrological settings may be significantly diachronous. These results call into question the leads and lags that we might infer from a ‘naı¨ve’ interpretation of benthic d18O as a sea-level proxy, with a direct bearing on the mechanisms that we may propose to explain glacial–interglacial climate transitions.