English   español  
Please use this identifier to cite or link to this item: http://hdl.handle.net/10261/80101
Share/Impact:
Statistics
logo share SHARE logo core CORE   Add this article to your Mendeley library MendeleyBASE

Visualizar otros formatos: MARC | Dublin Core | RDF | ORE | MODS | METS | DIDL
Exportar a otros formatos:
Title

Reexposure and advection of 14C-depleted organic carbon from old deposits at the upper continental slope

AuthorsTesi, T.; Puig, Pere ; Palanques, Albert
Issue DateDec-2010
PublisherAmerican Geophysical Union
CitationGlobal Biogeochemical Cycles 24(4): GB4002 (2010)
AbstractOutcrops of old strata at the shelf edge resulting from erosive gravity-driven flows have been globally described on continental margins. The reexposure of old strata allows for the reintroduction of aged organic carbon (OC), sequestered in marine sediments for thousands of years, into the modern carbon cycle. This pool of reworked material represents an additional source of 14C-depleted organic carbon supplied to the ocean, in parallel with the weathering of fossil organic carbon delivered by rivers from land. To understand the dynamics and implications of this reexposure at the shelf edge, a biogeochemical study was carried out in the Gulf of Lions (Mediterranean Sea) where erosive processes, driven by shelf dense water cascading, are currently shaping the seafloor at the canyon heads. Mooring lines equipped with sediment traps and current meters were deployed during the cascading season in the southwestern canyon heads, whereas sediment cores were collected along the sediment dispersal system from the prodelta regions down to the canyon heads. Evidence from grain-size, X-radiographs and 210Pb activity indicate the presence in the upper slope of a shelly-coarse surface stratum overlying a consolidated deposit. This erosive discontinuity was interpreted as being a result of dense water cascading that is able to generate sufficient shear stress at the canyon heads to mobilize the coarse surface layer, eroding the basal strata. As a result, a pool of aged organic carbon (Δ14C = −944.5 ± 24.7‰; mean age 23,650 ± 3,321 ybp) outcrops at the modern seafloor and is reexposed to the contemporary carbon cycle. This basal deposit was found to have relatively high terrigenous organic carbon (lignin = 1.48 ± 0.14 mg/100 mg OC), suggesting that this material was deposited during the last low sea-level stand. A few sediment trap samples showed anomalously depleted radiocarbon concentrations (Δ14C = −704.4 ± 62.5‰) relative to inner shelf (Δ14C = −293.4 ± 134.0‰), mid-shelf (Δ14C = −366.6 ± 51.1‰), and outer shelf (Δ14C = −384 ± 47.8‰) surface sediments. Therefore, although the major source of particulate material during the cascading season is resuspended shelf deposits, there is evidence that this aged pool of organic carbon can be eroded and laterally advected downslope
DescriptionTesi, T. ... et al.-- 11 pages, 6 figures
Publisher version (URL)http://dx.doi.org/10.1029/2009GB003745
URIhttp://hdl.handle.net/10261/80101
DOI10.1029/2009GB003745
Identifiersdoi: 10.1029/2009GB003745
issn: 0886-6236
e-issn: 1944-9224
Appears in Collections:(ICM) Artículos
Files in This Item:
File Description SizeFormat 
Tesi_et_al_2010.pdf1,39 MBAdobe PDFThumbnail
View/Open
Show full item record
Review this work
 

Related articles:


WARNING: Items in Digital.CSIC are protected by copyright, with all rights reserved, unless otherwise indicated.