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Title: Diagenetic formation of gypsum and dolomite in a cold-water coral mound in the Porcupine Seabight, off Ireland
Authors: Pirlet, Hans ×
Wehrmann, Laura M.
Brunner, Benjamin
Frank, Norbert
Dewanckele, Jan
Van Rooij, David
Foubert, Anneleen
Swennen, Rudy
Naudts, Lieven
Boone, Matthieu
Cnudde, Veerle
Henriet, Jean-Pierre #
Issue Date: 2010
Publisher: Blackwell Science
Series Title: Sedimentology vol:57 issue:3 pages:786-805
Abstract: Authigenic gypsum was found in a gravity core, retrieved from the top of Mound Perseverance, a giant cold-water coral mound in the Porcupine Basin, off Ireland. The occurrence of gypsum in such an environment is intriguing, because gypsum, a classic evaporitic mineral, is undersaturated with respect to sea water. Sedimentological, petrographic and isotopic evidence point to diagenetic formation of the gypsum, tied to oxidation of sedimentary sulphide minerals (i.e. pyrite). This oxidation is attributed to a phase of increased bottom currents which caused erosion and enhanced inflow of oxidizing fluids into the mound sediments. The oxidation of pyrite produced acidity, causing carbonate dissolution and subsequently leading to pore-water oversaturation with respect to gypsum and dolomite. Calculations based on the isotopic compositions of gypsum and pyrite reveal that between 21·6% and 28·6% of the sulphate incorporated into the gypsum derived from pyrite oxidation. The dissolution of carbonate increased the porosity in the affected sediment layer but promoted lithification of the sediments at the sediment-water interface. Thus, authigenic gypsum can serve as a signature for diagenetic oxidation events in carbonate-rich sediments. These observations demonstrate that fluid flow, steered by environmental factors, has an important effect on the diagenesis of coral mounds.
ISSN: 0037-0746
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Division of Geology
× corresponding author
# (joint) last author

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