Abstract
The Gulf of Cadiz constitutes a prime area to study teleconnections between the North Atlantic Ocean and climate change in the Mediterranean realm. In particular, the highly saline Mediterranean Outflow Water (MOW) is an important modulator of the North Atlantic salt budget on intermediate water levels. However, our understanding of its paleoceanographic evolution is poorly constrained due to the lack of high-resolution proxy records that predate the last glacial cycle. Here we present the first continuous and high-resolution (~ 1 kyr) benthic δ18O and δ13C as well as grain size records from Integrated Ocean Drilling Program Site U1386 representing the last ~570 kyr. We find three distinct phases of MOW variability throughout the Late to Middle Pleistocene at Site U1386 associated with prominent shifts in its composition and flow strength. We attribute this long-term variability to changes in water mass sourcing of the MOW. Superimposed on the long-term change in water mass sourcing is the occurrence of distinct and precession paced δ18O enrichment events, which contrast the pattern of global ice volume change as inferred from the global mean δ18O signal (i.e., LR04) but mimics that of the adjacent Mediterranean Sea. We attribute these enrichment events to a profound temperature reduction and salinity increases of the MOW, aligning with similar changes in the Mediterranean source region. These events might further signify ice volume increases as inferred from significant sea level drops recorded in the Red Sea and/or increased influence of North Atlantic intermediate water masses when MOW influence was absent at Site U1386.
Original language | English |
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Pages (from-to) | 634-647 |
Number of pages | 14 |
Journal | Paleoceanography |
Volume | 32 |
Issue number | 6 |
DOIs | |
Publication status | Published - 1 Jun 2017 |
Funding
First, we would like to thank two anonymous reviewers and Associate Editor Min-Te Chen for their careful handling of the manuscript as well as for their constructive comments and suggestions to improve our manuscript. We acknowledge the Integrated Ocean Drilling Program (IODP) for providing the samples used in this study as well as A. van Dijk at Utrecht University and J. Nicolson at Cambridge University for analytical support. This research was funded by NWO-ALW grant (project 865.10.001) to Lucas J. Lourens. B. de Boer receives funding from the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement 660814. All data presented in this study are available online via www.pangea.de.
Funders | Funder number |
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European Union's Horizon 2020 research and innovation program | |
IODP | |
NWO-ALW | 865.10.001 |
Horizon 2020 Framework Programme | 660814 |
Universiteit Utrecht |
Keywords
- glacial δO enrichment events
- Mediterranean Outflow Water (MOW)
- Middle to Late Pleistocene
- North Atlantic Intermediate Water
- precession forcing of MOW