KNAW Repository

Diagenetic pyritisation under eastern Mediterranean sapropels caused by downward sulphide diffusion

Passier, H.F. and Middelburg, J.J. and Van Os, B.J.H. and De Lange, G.J. (1996) Diagenetic pyritisation under eastern Mediterranean sapropels caused by downward sulphide diffusion. Geochimica et Cosmochimica Acta, 60, 751-763. ISSN 0016-7037.

[img]PDF - Published Version
Restricted to KNAW only

1768Kb

Official URL: http://dx.doi.org/10.1016/0016-7037(95)00419-X

Abstract

Recurrent organic-rich layers (sapropels) in eastern Mediterranean sediments are enriched in C-org, Fe, and S. Sulphur and Fe are enriched in a zone immediately below the sapropels, whereas C-org is not. delta(34)S values of bulk sediments and simple mass-balance calculations indicate that SO42- reduction has taken place in an open system, with all HS- formed at, or close to, the sediment surface. Formation of pyrite in the sapropel was Fe-limited and consequently, excess HS- was able to migrate downwards (downward sulphidisation). This resulted in the formation of pyrite below the sapropel by reaction of this HS- with solid-phase ferric iron and Fe2+ diffusing upwards from underlying sediments. The Fe2+ source probably includes Fe (hydr)oxide layers formed at former oxidation fronts above previously deposited and buried sapropels. This downward sulphidisation mechanism allows accumulation of twice as much S in alternating organic-rich- anoxic/organic-poor-suboxic sediments compared to what is preserved in organic-rich anoxic sediments. [KEYWORDS: Deep-sea sediments; metal-rich layers; quaternary depositional sequences; semi-euxinic sediments; pyrite formation; marine-sediments; organic-carbon; black-sea; sulfate reduction; sulfur speciation]

Item Type:Article
Institutes:Nederlands Instituut voor Ecologie (NIOO)
ID Code:12167
Deposited On:25 Nov 2011 01:00
Last Modified:31 Mar 2014 11:07

Repository Staff Only: item control page