Rare-earth elements and Nd and Pbisotopes as source indicators for Labrador Sea clay-size sediments during Heinrich event 2

Authors

Larry Benson, University of Colorado at BoulderFollow
Don Barber, University of Colorado at Boulder
John T. Andrews, University of Colorado at Boulder
Howard E. Taylor, United States Geological SurveyFollow
Paul Lamothe, United States Geological Survey

Date of this Version

2003

Citation

Quaternary Science Reviews 22 (2003) 881–889; doi:10.1016/S0277-3791(03)00011-8

Abstract

Elemental abundances and Nd and Pb isotope ratios were determined on samples from the carbonate-free, clay-size fractions of sediments from intervals above, within, and below Heinrich event 2 (H-2) in core HU87-9 from the Northwest Labrador Sea slope. In HU87-9, rare-earth element (REE) distributions and elemental concentrations within the H-2 event are distinct from those outside this event. ɛ_Nd(0) and ²⁰⁶Pb/²⁰⁴Pbdata also indicate different values for sediments deposited within and outside the H-2 event. Comparisons of REE patterns from the H-2 interval with those from bedrock units in Baffin Island, northern Quebec, and Labrador indicate that the Lake Harbour Group (LHG), which crops out on the north side of the Hudson Strait, is the most probable bedrock source of the clay-size fraction found within the H-2 interval in HU87-9. The Tasiuyak Gneiss (TG) and Lac Lomier Complex (LLC) have REE patterns (including a negative Eu anomaly) similar to those found in H-2 sediments; however, the La/Ybratios of these units are smaller than those associated with H-2 sediments. The Nd and Pbisotope data support and complement REE-based interpretations of provenance; i.e., the Nd–Pb signatures of sediments deposited at the HU87-9 site during the H-2 event are similar to Nd–Pbsignatures obtained on diamicts from the western end of Hudson Strait.