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{sup 210}Pb-Excess and Sediment Accumulation Rates at the Iberian Continental Margin

Abstract

Sediments from the continental shelf, slope, and rise at the continental margin of northern Portugal and the adjacent Iberian abyssal basin were analysed for 210Pb, {sup 226}Ra, {sup 137}Cs and {sup 14}C. Pb-210 derived sedimentation rates at the continental shelf off the Portuguese coast were 0.2-0.6 cm/a. In some cores from fine sediment deposits at the outer shelf, the {sup 210}Pb excess continuum was interrupted and sediment layers were missing, suggesting that events such as sediment slides could have occurred. Higher sedimentation rates were determined in locations at the rise of the continental slope, confirming enhanced deposition by sediment slides. In the deeper Iberian Abyssal Basin, using the {sup 14}C age of sediment layers the sedimentation rate was determined at 3.2 cm/ka, thus four orders of magnitude lower than at the continental shelf. The spatial distribution of sedimentation rates determined by radionuclide based chronologies, suggested that fine sediments from river discharges are deposited mainly at the outer continental shelf. These deposits may became unstable with time and, occasionally, originate sediment slides that are drained by the canyons and reach the deep sea. The Iberian abyssal basin receives some advective contribution of these sediment slides and the sedimentation rate is one  More>>
Authors:
Carvalho, F. P.; Oliveira, J. M.; Soares, A. M. [1] 
  1. Nuclear and Technological Institute, Sacavem (Portugal)
Publication Date:
Jul 15, 2013
Product Type:
Conference
Report Number:
IAEA-CN-186/5
Resource Relation:
Conference: International Symposium on Isotopes in Hydrology, Marine Ecosystems and Climate Change Studies, Monaco (Monaco), 27 Mar - 1 Apr 2011; Other Information: 6 figs., 3 tabs., 18 refs.; Related Information: In: Isotopes in Hydrology, Marine Ecosystems and Climate Change Studies. Vol. I. Proceedings of an International Symposium| 547 p.
Subject:
58 GEOSCIENCES; ATLANTIC OCEAN; CANYONS; CARBON 14; CESIUM 137; CONTINENTAL SHELF; CONTINENTAL SLOPE; LAYERS; LEAD 210; PORTUGAL; RADIUM 226; RIVERS; SEDIMENTATION; SEDIMENTS; SHORES; SPATIAL DISTRIBUTION
OSTI ID:
22122099
Research Organizations:
International Atomic Energy Agency, Department of Nuclear Sciences and Applications, Vienna (Austria)
Country of Origin:
IAEA
Language:
English
Other Identifying Numbers:
Other: ISSN 0074-1884; ISBN 978-92-0-135610-9; TRN: XA13R0856078210
Availability:
Also available on-line: http://www-pub.iaea.org/MTCD/publications/PDF/Pub1580_vol1_web.pdf; Enquiries should be addressed to IAEA, Marketing and Sales Unit, Publishing Section, E-mail: sales.publications@iaea.org; Web site: http://www.iaea.org/books
Submitting Site:
INIS
Size:
page(s) 451-462
Announcement Date:
Aug 27, 2013

Citation Formats

Carvalho, F. P., Oliveira, J. M., and Soares, A. M. {sup 210}Pb-Excess and Sediment Accumulation Rates at the Iberian Continental Margin. IAEA: N. p., 2013. Web.
Carvalho, F. P., Oliveira, J. M., & Soares, A. M. {sup 210}Pb-Excess and Sediment Accumulation Rates at the Iberian Continental Margin. IAEA.
Carvalho, F. P., Oliveira, J. M., and Soares, A. M. 2013. "{sup 210}Pb-Excess and Sediment Accumulation Rates at the Iberian Continental Margin." IAEA.
@misc{etde_22122099,
title = {{sup 210}Pb-Excess and Sediment Accumulation Rates at the Iberian Continental Margin}
author = {Carvalho, F. P., Oliveira, J. M., and Soares, A. M.}
abstractNote = {Sediments from the continental shelf, slope, and rise at the continental margin of northern Portugal and the adjacent Iberian abyssal basin were analysed for 210Pb, {sup 226}Ra, {sup 137}Cs and {sup 14}C. Pb-210 derived sedimentation rates at the continental shelf off the Portuguese coast were 0.2-0.6 cm/a. In some cores from fine sediment deposits at the outer shelf, the {sup 210}Pb excess continuum was interrupted and sediment layers were missing, suggesting that events such as sediment slides could have occurred. Higher sedimentation rates were determined in locations at the rise of the continental slope, confirming enhanced deposition by sediment slides. In the deeper Iberian Abyssal Basin, using the {sup 14}C age of sediment layers the sedimentation rate was determined at 3.2 cm/ka, thus four orders of magnitude lower than at the continental shelf. The spatial distribution of sedimentation rates determined by radionuclide based chronologies, suggested that fine sediments from river discharges are deposited mainly at the outer continental shelf. These deposits may became unstable with time and, occasionally, originate sediment slides that are drained by the canyons and reach the deep sea. The Iberian abyssal basin receives some advective contribution of these sediment slides and the sedimentation rate is one order of magnitude higher than in other abyssal basins of the NE Atlantic Ocean. (author)}
place = {IAEA}
year = {2013}
month = {Jul}
}