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


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 horizontal fluxes of 230Th may be partly controlled by physical parameters, 230Th excesses cannot be unequivocally correlated with sedimentation rates and/or productivity as reported elsewhere. In this subarctic basin characterized by low overall organic carbon burial, the 238U/232Th ratio appears to be a sensible geochemical indicator of organic activity and paleoproductivity.

Age data have been obtained by interpolation between 18O stage boundaries.

DOI https://doi.org/10.1594/PANGAEA.711768
Related Identifier https://doi.org/10.1130/0091-7613(1990)018<0162:ROTUID>2.3.CO
Metadata Access https://ws.pangaea.de/oai/provider?verb=GetRecord&metadataPrefix=datacite4&identifier=oai:pangaea.de:doi:10.1594/PANGAEA.711768
Creator Hillaire-Marcel, Claude; Aksu, Ali E; Causse, Christiane; de Vernal, Anne; Ghaleb, Bassam
Publisher PANGAEA - Data Publisher for Earth & Environmental Science
Publication Year 1990
Rights Creative Commons Attribution 3.0 Unported
OpenAccess true
Language English
Resource Type Dataset
Format text/tab-separated-values
Size 352 data points
Discipline Earth System Research
Spatial Coverage (-48.369 LON, 58.209 LAT); Labrador Sea
Temporal Coverage Begin 1985-10-04T08:45:00Z
Temporal Coverage End 1985-10-13T21:01:00Z