Edith Vincent

Phase relationships between millennial‐scale events 64,000–24,000 years ago

A core recovered on the Iberian margin off southern Portugal can be correlated with Greenland ice cores using oxygen isotope variability in planktonic foraminifera which closely matches the ice core records of temperature over Greenland. Our age model identifies the base of every interstadial between 64,000 and 24,000 years ago and uses the Greenland Ice Core Project (GRIP) timescale. The oxygen isotope signal in benthic foraminifera (on this GRIP-based timescale) is quite different from the planktonic record and resembles the temperature record over Antarctica when this is synchronized with Greenland using the record of methane in the atmospheric air in the polar ice cores. We interpret the benthic record as indicating significant fluctuations in ice volume during millennial events, and we suggest that Antarctic temperature changed as a function of ice volume.

Paleoceanographic reconstructions from planktonic foraminifera off the Iberian Margin: Temperature, salinity, and Heinrich events

A quantitative analysis of planktonic foraminifera in a core from the Iberian Margin allows a reconstruction of the evolution of oceanographic parameters during the last glacial cycle with a resolution of ∼1000 years. A principal component analysis performed on 19 species allows the identification of 11 intervals characterized by increased abundances of the subpolar species. The youngest six of these intervals are correlated with the last 6 Heinrich events (HEs). The five cold events older than stage 4 are dated at 81, 90, 110, 129, and 140 ka, respectively. Paleotemperatures reconstructed using the modern analog technique indicate 4°C decreases during all even-numbered isotopic stages and stage 3. During the HEs, temperature decreases reach ∼10°C and seawater δ18O anomalies reach ∼1‰. Temperature and salinity reconstructions indicate that the environment of the Iberian Margin has been under the combined influence of global factors such as the migration of the polar front and iceberg discharge and of regional factors such as the precipitation/evaporation regime on both oceanic and continental area.

Pleistocene Climates in the Atlantic and Pacific Oceans: A Reevaluated Comparison Based on Deep-Sea Sediments

Variations of the Globorotalia menardii complex in cores from the Indian Ocean can be interpreted as indicating climatic changes that are opposite to trends exhibited by the total planktonic fauna. The questionable value of correlations between different water masses based on a single species can be shown by Neogloboquadrina dutertrei subcretacea in cores obtained off the coast of California and Baja California. This information, in addition to previous correlations between Quaternary cores of the Atlantic and Pacific oceans, indicates that the Pleistocene history of the two oceans was parallel.