Late Holocene dust provenance at Siple Dome, Antarctica

• Published in: Quaternary Science Reviews
• Main Authors: Koffman, Bess G., Goldstein, Steven L., Winckler, Gisela, Kaplan, Michael R., Kreutz, Karl J., Bolge, Louise, Bory, Aloys, Biscaye, Pierre
• Other Authors: Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG), Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD France-Nord )
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: Antarctica; Dust provenance; Sr-Nd isotopes; Ice cores; Southern ocean; Gaussberg volcano; [SDU]Sciences of the Universe [physics]; Antarctic; East Antarctica; Gaussberg; Kaiser-Wilhelm-II.-Land; McMurdo Dry Valleys; Patagonia; Ross Sea; Siple; Siple Dome; Southern Ocean; West Antarctica; Wilhelm II Land; Antarc*; Enderby Land; ice core; Kaiser Wilhelm II land
• Online Access: https://insu.hal.science/insu-03664859; https://doi.org/10.1016/j.quascirev.2021.107271

International audience Compositions of mineral dust in ice cores serve as tracers of paleo-atmospheric circulation patterns, providing linkages between sources and sinks. Here we document the geochemical makeup of dust reaching continental West Antarctica, on late Holocene samples from the Siple Dome A ice core (spanning ∼1030-1800 C.E). The Nd-Sr isotope signature is unusual for Antarctic ice core dust samples. Siple Dome data are characterized by low Nd isotope ratios (as low as εNd = -16.3) along with low Sr isotope ratios (highest 87 Sr/ 86 Sr = 0.7102) compared with other Antarctic dust signatures. A well-defined inverse correlation between Sr-Nd isotope ratios indicates two primary mixing sources. The low εNd-values indicate involvement of ancient (Archean-to-early Proterozoic) continental crust, as either the direct source or as a precursor of the source, and the low Sr-values require low Rb/Sr ratios that often reflect high-grade metamorphism. The known Antarctic terrane with these characteristics is parts of Enderby Land, nearly at the opposite end of Antarctica. The isotopic signature of the second end-member is compatible with West Antarctic volcanoes or Patagonia in South America. The Sr-Nd isotopes and trace element abundances are also chemically compatible with mixing between volcanic material from Gaussberg, a small lamproite volcano in Kaiser Wilhelm II Land in coastal East Antarctica whose source is ancient lithospheric mantle, with dust from Patagonia or material from West Antarctic volcanoes. We assess these potential mixing scenarios and conclude that Siple Dome's unusual geochemical signature can best be explained by a mixture of Patagonian dust and a Gaussberg-like source, with additional minor contributions from old eroded Archean-to-early Proterozoic bedrock sources such as those in Enderby Land. Moreover, Siple Dome dust compositions are distinct from dust deposited on Taylor and Clark Glaciers in the McMurdo Dry Valleys of the western Ross Sea, precluding the Dry Valleys as a late ...