The Marine Isotope Stage 19 in the mid-latitude North Atlantic Ocean: astronomical signature and intra-interglacial variability

• Published in: Quaternary Science Reviews
• Main Authors: Ferretti P, Crowhurst SJ, Naafs BDA, Barbante C
• Other Authors: Ferretti, P, Crowhurst, Sj, Naafs, Bda, Barbante, C
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2015
• Subjects: North Atlantic; Pleistocene; Precession; Insolation; Foraminifera; Stable isotopes; Oxygen isotope stratigraphy; IODP Site U1313; Settore GEO/02 - Geologia Stratigrafica e Sedimentologica; Planktonic foraminifera
• Online Access: http://hdl.handle.net/10278/3710902; https://doi.org/10.1016/j.quascirev.2014.10.024; https://www.sciencedirect.com/science/article/pii/S0277379114004119

Since the seminal work by Hays etal. (1976), a plethora of studies has demonstrated a correlation between orbital variations and climatic change. However, information on how changes in orbital boundary conditions affected the frequency and amplitude of millennial-scale climate variability is still fragmentary. The Marine Isotope Stage (MIS) 19, an interglacial centred at around 785ka, provides an opportunity to pursue this question and test the hypothesis that the long-term processes set up the boundary conditions within which the short-term processes operate. Similarly to the current interglacial, MIS 19 is characterised by a minimum of the 400-kyr eccentricity cycle, subdued amplitude of precessional changes, and small amplitude variations in insolation. Here we examine the record of climatic conditions during MIS 19 using high-resolution stable isotope records from benthic and planktonic foraminifera from a sedimentary sequence in the North Atlantic (Integrated Ocean Drilling Program Expedition 306, Site U1313) in order to assess the stability and duration of this interglacial, and evaluate the climate system's response in the millennial band to known orbitally induced insolation changes. Benthic and planktonic foraminiferal δ18O values indicate relatively stable conditions during the peak warmth of MIS 19, but sea-surface and deep-water reconstructions start diverging during the transition towards the glacial MIS 18, when large, cold excursions disrupt the surface waters whereas low amplitude millennial scale fluctuations persist in the deep waters as recorded by the oxygen isotope signal. The glacial inception occurred at ~779ka, in agreement with an increased abundance of tetra-unsaturated alkenones, reflecting the influence of icebergs and associated meltwater pulses and high-latitude waters at the study site. After having combined the new results with previous data from the same site, and using a variety of time series analysis techniques, we evaluate the evolution of millennial climate variability in ...