History of water-column anoxia in the Black Sea indicated by pyrite framboid size distributions

Richard T. Wilkin, Michael Allan Arthur, Walter E. Dean

Research output: Contribution to journalArticle

210 Citations (Scopus)

Abstract

A detailed study of size distributions of framboidal pyrite in Holocene Black Sea sediments establishes the timing of a change from deposition under an oxic water column to deposition under an anoxic and sulfidic water column. In the most recent carbonate-rich sediments (Unit I) and in the organic carbon-rich sapropel (Unit II), framboid size distributions are remarkably uniform (mean diameter= 5 μm); over 95% of the framboids in Unit I and Unit II are < 7 μm in diameter. These properties of framboidal pyrite are consistent with framboid nucleation and growth within an anoxic and sulfidic water column, followed by transport to the sediment-water interface, cessation of pyrite growth due to the exhaustion of reactive iron, and subsequent burial. In contrast, the organic carbon-poor sediments of lacustrine Unit III contain pyrite framboids that are generally much larger in size (mean diameter = 10 μm). In Unit III, over 95% of the framboids are < 25 μm in diameter, 40% of framboids are between 7 μm and 25 μm, and framboids up to 50 μm in diameter are present. This distribution of sizes suggests framboid nucleation and growth within anoxic sediment porewaters. These new data on size distributions of framboidal pyrite confirm that the development of water-column anoxia in the Black Sea coincided with the initiation of deposition of laminated Unit II sapropels.

Original languageEnglish (US)
Pages (from-to)517-525
Number of pages9
JournalEarth and Planetary Science Letters
Volume148
Issue number3-4
StatePublished - May 1 1997

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anoxia
Black Sea
pyrites
pyrite
sediments
water column
histories
Sediments
Water
history
sapropel
water
Organic carbon
nucleation
Anoxic sediments
Nucleation
organic carbon
exhaustion
anoxic sediment
carbon

All Science Journal Classification (ASJC) codes

  • Geochemistry and Petrology
  • Geophysics

Cite this

Wilkin, Richard T. ; Arthur, Michael Allan ; Dean, Walter E. / History of water-column anoxia in the Black Sea indicated by pyrite framboid size distributions. In: Earth and Planetary Science Letters. 1997 ; Vol. 148, No. 3-4. pp. 517-525.
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History of water-column anoxia in the Black Sea indicated by pyrite framboid size distributions. / Wilkin, Richard T.; Arthur, Michael Allan; Dean, Walter E.

In: Earth and Planetary Science Letters, Vol. 148, No. 3-4, 01.05.1997, p. 517-525.

Research output: Contribution to journalArticle

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