Response of Th/U in deep Labrador Sea sediments (ODP Site 646 to changes in sedimentation rates and paleoproductivities

Abstract

Research Article| February 01, 1990 Response of Th/U in deep Labrador Sea sediments (ODP Site 646 to changes in sedimentation rates and paleoproductivities C. Hillaire-Marcel; C. Hillaire-Marcel 1GEOTOP, Université du Québec à Montréal, BP 8888, succursale A, Montréal, Québec H3C 3P8, Canada Search for other works by this author on: GSW Google Scholar A. Aksu; A. Aksu 2Department of Earth Sciences, Memorial University of Newfoundland, St. John's, Newfoundland A1 B 3X5, Canada Search for other works by this author on: GSW Google Scholar C. Causse; C. Causse 3Laboratoire de Géologie du Quaternaire, CNRS Luminy, case 907, 13288 Marseille Cedex 9, France Search for other works by this author on: GSW Google Scholar A.de Vernal; A.de Vernal 1GEOTOP, Université du Québec à Montréal, BP 8888, succursale A, Montréal, Québec H3C 3P8, Canada Search for other works by this author on: GSW Google Scholar B. Ghaleb B. Ghaleb 1GEOTOP, Université du Québec à Montréal, BP 8888, succursale A, Montréal, Québec H3C 3P8, Canada Search for other works by this author on: GSW Google Scholar Author and Article Information C. Hillaire-Marcel 1GEOTOP, Université du Québec à Montréal, BP 8888, succursale A, Montréal, Québec H3C 3P8, Canada A. Aksu 2Department of Earth Sciences, Memorial University of Newfoundland, St. John's, Newfoundland A1 B 3X5, Canada C. Causse 3Laboratoire de Géologie du Quaternaire, CNRS Luminy, case 907, 13288 Marseille Cedex 9, France A.de Vernal 1GEOTOP, Université du Québec à Montréal, BP 8888, succursale A, Montréal, Québec H3C 3P8, Canada B. Ghaleb 1GEOTOP, Université du Québec à Montréal, BP 8888, succursale A, Montréal, Québec H3C 3P8, Canada Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1990) 18 (2): 162–165. https://doi.org/10.1130/0091-7613(1990)018<0162:ROTUID>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation C. Hillaire-Marcel, A. Aksu, C. Causse, A.de Vernal, B. Ghaleb; Response of Th/U in deep Labrador Sea sediments (ODP Site 646 to changes in sedimentation rates and paleoproductivities. Geology 1990;; 18 (2): 162–165. doi: https://doi.org/10.1130/0091-7613(1990)018<0162:ROTUID>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract 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. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.