(Table 1) Th and U concentrations and activity ratios in deep-sea sediments at ODP Hole 105-646B ...

• Main Authors: Hillaire-Marcel, Claude, Aksu, Ali E, Causse, Christiane, de Vernal, Anne, Ghaleb, Bassam
• Format: Dataset
• Language: English
• Published: PANGAEA 1990
• Subjects: AGE; Sample code/label; Sample, optional label/labor no; Thorium-232; Thorium-232, standard deviation; Uranium-238; Uranium-238, standard deviation; Uranium-234/Uranium-238 activity ratio; Uranium-234/Uranium-238 activity ratio, standard deviation; Uranium-238/Thorium-232 ratio; Uranium-238/Thorium-232 ratio error; Thorium-230/Thorium-232 ratio; Thorium-230/Thorium-232 ratio error; Thorium-230/Uranium-234 activity ratio; Thorium-230/Uranium-234 activity ratio, standard deviation; Age, error; Thorium-230; Drilling/drill rig; DSDP/ODP/IODP sample designation; Alpha spectrometry; Calculated; Leg105; Joides Resolution; Ocean Drilling Program ODP; Greenland; Labrador Sea
• Online Access: https://dx.doi.org/10.1594/pangaea.711768; https://doi.pangaea.de/10.1594/PANGAEA.711768

The Labrador Sea is a particularly suitable high-latitude basin for investigating U and Th behavior in deep-sea sediments. During the late Quaternary, the cyclic development and decay of huge ice sheets on adjacent land masses resulted in large-amplitude changes in sedimentation rates and organic paleoproductivities. The resulting magnification of U and Th response is well illustrated by high-resolution studies on piston-cored sediments from the Greenland continental rise at Ocean Drilling Program Leg 105 Site 646 spanning isotopic stages 8 to 1. Our results show a clear positive correlation of 238U/232Th ratios with organic paleoproductivity indicators (e.g., dinocyst) due to U uptake in the water column and/or during the early early diagenesis of organic matter responding to carbon fluxes and to their climate forcing. 230Th excesses over 234U exceed the theoretical value of the 230Th rain from the overlying water column, indicating lateral input possibly from the Greenland slope and shelf. Because these ... : Age data have been obtained by interpolation between 18O stage boundaries. ...