The project CINNAMOW aims to reconstruct Late Pliocene-Early Pleistocene (~3.4 to ~2.3 Ma) climatic and oceanographic conditions at the Iberian Margin. This study will provide new insights into one of the major climate transitions in past Earth's climate, the shift from the warm Pliocene climate to the initiation of the Northern Hemisphere glaciations (NHG), in which the climate became characterized by the alternation between glacial and interglacial periods. The outcomes of this project will also help modelers to provide better predictions of future climate scenarios, since the Pliocene is the most recent interval in which greenhouse gases concentrations were as high as the levels we recently reached due to the anthropogenic pollution.
Even though the scientific community has carried out a great effort to unravel the mechanisms and processes that gave rise to this climatic cooling trend, the initiation of the NHG is still poorly understood. Recently, it has been suggested that the Mediterranean Overflow Water (MOW) may have played a major role modifying the patterns of Atlantic Meridional Overturning Circulation (AMOC) by enhancing deep water formation in the North Atlantic. Reconstructing the physicochemical variations in the MOW during this interval will contribute to understand the role of this current in global ocean circulation changes.
We are studying sediments from Site U1391, recently recovered from the Southwest Iberian margin during the Integrated Ocean Drilling Program (IODP) Expedition 339. This expedition provided for the first time long sediment cores from the area of the Gulf of Cadiz and SW Iberia, which guarantees the novelty and extraordinary interest of the data obtained in this project. Located in the path of the MOW, Site U1391 offers the possibility to conduct for the first time a high resolution study of MOW variations during the Plio-Pleistocene transition. Moreover, this site is placed at the Iberian Margin, a region that has been proved to be very valuable in recording climatic changes during the Pleistocene. In this regard, the sediments from Site U1391 offer the possibility to directly compare changes in MOW with regional climatic records. This comparison will shed light on the correlation of regional climate aridification and intensification of MOW. Besides, the regional climatic records of the Late Pliocene-Early Pleistocene interval will be deeply relevant to improve model simulations, not only to get a better picture about past climate conditions but also to produce better simulations of future climate in the current context of climate warming.
To accomplish this project we will use a multi-proxy approach that includes micropaleontological, sedimentological and geochemical proxies:
1) Benthic foraminifer oxygen stable isotopes (δ18O) to construct a precise age model;
2) Grain size analysis, for information about the fluctuations in the strength of the outflow;
3) Benthic foraminifer oxygen and carbon stable isotopes, and trace elements (particularly Mg/Ca), to reconstruct MOW changes in temperature and salinity;
4) Biomarker analysis to reconstruct sea surface temperature changes at the SW Iberian Margin (alkenone paleothermometry), productivity conditions in the area (concentration of alkenones), and dust input (alkanes and alcohols) to reconstruct wind patterns.