Abrupt shoaling of the nutricline in response to massive freshwater flooding at the onset of the last interglacial sapropel event
Grelaud, Michael (Universitat Autònoma de Barcelona. Institut de Ciència i Tecnologia Ambientals)
Marino, Gianluca (Universitat Autònoma de Barcelona. Institut de Ciència i Tecnologia Ambientals)
Ziveri, Patrizia (Universitat Autònoma de Barcelona. Departament de Biologia Animal, de Biologia Vegetal i d'Ecologia)
Rohling, Eelco J. (University of Southampton. National Oceanography Centre)

Fecha:	2012
Resumen:	A detailed assessment of the respective roles of production, export, and subsequent preservation of organic carbon (Corg) in the eastern Mediterranean (EMED) sediments during the formation of sapropels remains elusive. Here we present new micropaleontological results for both surface samples taken at several locations in the EMED and last interglacial sapropel S5 from core LC21 in the southeastern Aegean Sea. A strong exponential anticorrelation between relative abundances of the lower photic zone coccolithophore Florisphaera profundain the surface sediments and modern concentrations of chlorophyll a (Chl-a) at the sea surface suggests thatF. profunda percentages can be used to track past productivity changes in the EMED. Prior to S5 deposition, an abrupt and large increase of F. profundapercentages in LC21 coincided (within the multidecadal resolution of the records) with the marked freshening of EMED surface waters. This suggests a strong coupling between freshwater-bound surface to intermediate water (density) stratification and enhanced upward advection of nutrients to the base of the photic zone, fuelling a productive deep chlorophyll maximum (DCM) underneath a nutrient-starved surface layer. Our findings imply that (at least) at the onset of sapropel formation physical and biogeochemical processes likely operated in tandem, enabling high Corg accumulation at the seafloor.
Ayudas:	European Commission 265103 Ministerio de Ciencia e Innovación CGL2009-10806
Derechos:	Tots els drets reservats.
Lengua:	Anglès
Documento:	Article ; recerca ; Versió publicada
Publicado en:	Paleoceanography, Vol. 27, Issue 3 (September 2012) , p. 3208, ISSN 1944-9186

DOI: 10.1029/2012PA002288

9 p, 2.2 MB

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