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Pyrite contents, microtextures, and sulfur isotopes in relation to formation of the youngest eastern Mediterranean sapropel

Passier, H.F. and Middelburg, J.J. and De Lange, G.J. and Bottcher, M.E. (1997) Pyrite contents, microtextures, and sulfur isotopes in relation to formation of the youngest eastern Mediterranean sapropel. Geology, 25, 519-522. ISSN 0091-7613.

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Official URL: http://dx.doi.org/10.1130/0091-7613(1997)025<0519:PCMASI>2.3.CO;2

Abstract

Pyrite within and below sapropels in the eastern Mediterranean is a result of microbial SO42- reduction within the sapropel, and the subsequent reaction of sulfide (HS-) with detrital Fe and Fe2+ diffusing upward from underlying sediments. Below the youngest Mediterranean sapropel, S1, pyrite (as much as 281 mu mol pyritic S/g) is mostly present as euhedral crystals, whereas within the sapropel only framboidal pyrite (as much as 360 mu mol pyritic S/g) has been detected. Framboidal microtextures indicate pyrite formation at the site of HS- production within the sapropel. Euhedral pyrite, below the sapropel, forms when sulfate reduction in the sapropel outcompetes iron liberation and supply, and HS- diffuses out of the sapropel. Sulfur isotope values of pyrite are extremely light in the sapropel (-37.3 parts per thousand to -38.2 parts per thousand) as well as below the sapropel (-45.6 parts per thousand and -49.6 parts per thousand), indicating that HS- has formed in a system with abundant SO42- and in the presence of oxidants. [KEYWORDS: Laboratory synthesis; marine-sediments]

Item Type:Article
Institutes:Nederlands Instituut voor Ecologie (NIOO)
ID Code:10525
Deposited On:25 Nov 2011 01:00
Last Modified:15 Jan 2014 09:35

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