Last Glacial Maximum from Blake Ridge sediments

• Main Authors: M. Gutjahr A, M. Frank A, C. H. Stirling A, L. D. Keigwin B, A. N. Halliday C
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2007
• Subjects: NADW; North Atlantic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.540.6319; http://www.geomar.de/fileadmin/personal/fb1/p-oz/mfrank/Gutjahr_et_al_2008.pdf

Tel.: [phone].appears to be influenced by downslope and lateral sediment redistribution. Our data suggest that these radiogenic signals were formed at shallow depths in Florida current waters, compromising the recorded ambient deep water Nd isotope signal in the Blake Ridge Fe–Mn oxyhydroxide coatings from intermediate depths during the Holocene and the deglaciation. The unradiogenic Nd-isotopic composition typical of present-day NADW is not detectable along the Blake Ridge for any water depth during the LGM. Unlike the deglacial and Holocene sections, the intermediate core from 1790 m water depth did not experience significant sediment focusing during the LGM, in accord with the higher current velocities at this depth, suggesting that at this site an ambient LGM bottom water Nd isotope signal was recorded. Assuming this to be correct, our results indicate that the εNd of the shallower glacial equivalent of NADW, the Glacial North Atlantic Intermediate Water (GNAIW) may have been as radiogenic as −9.7±0.4. Since the authigenic Nd isotope compositions of the Holocene and the deglacial sections of the intermediate depth sediment core were biased towards a shallow water signal, this first determination of a GNAIW εNd for the LGM will have to be corroborated by results from other locations and archives.located within the main water body of the WBUC coinciding depth. Above this depth the authigenic Nd-isotopic compositionNd isotope compositions similar to the typical present-day NADW εNd value of −13.5±0.5 were only extracted from sediments