Fluorine mobility during early diagenesis of carbonate sediment: An indicator of mineral transformations

Journal Article · Sun Sep 01 04:00:00 EDT 1991 · Geochimica et Cosmochimica Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(91)90368-F· OSTI ID:7235641

Rude, P D; Aller, R C ^[1]

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1. State Univ. of New York, Stony Brook (United States)

The abundant occurrence of calcium carbonate minerals in marine sediment, their well-documented dissolution or precipitation during diagenesis, and their high F content suggest that carbonate mineral diagenesis may be an important influence on F behavior in marine sediment. To test this hypothesis, the authors have examined the geochemistry of F in shallow carbonate mud bank sediment of Florida Bay, USA. The F content of biogenic calcium carbonate in Florida Bay varies with mineralogy, positively correlates with the Mg content of calcite, and occurs in similar abundance to Sr. Models of porewater distributions, direct solute flux measurements, and reaction rate estimates over the upper 0-16 cm of sediment from Bob Allen Key Bank predict net fluxes out of the sediment of 170 {mu}mol F/m{sup 2}/d, 230 {mu}mol Sr/m{sup 2}/d, and 5.6 mmol Ca/m{sup 2}/d. The loss of F, Sr, and Ca to fluorapatite precipitation, as predicted from a stoichiometric model of phosphate release, can be added to the transport-reaction model predicted net fluxes. A resulting, more complete mass balance model incorporating both carbonate mineral reactions and fluorapatite formation yields total release estimates of F, Sr, and Ca of 770 {mu}mol, 332 {mu}mol, and 53 mmol/m{sup 2}/d, respectively. The magnitude of these fluxes could cause significant mineralogical and chemical changes on rapid time scales in nearshore carbonate sediment. Fluorine is probably mobile in other carbonate deposits undergoing diagenetic alteration on short and longer time scales and is a powerful additional constraint on the rates and nature of carbonate mineral diagenesis.

• OSTI ID: 7235641
• Journal Information: Geochimica et Cosmochimica Acta; (United States), Journal Name: Geochimica et Cosmochimica Acta; (United States) Vol. 55:9; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

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58 GEOSCIENCES
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CARBONATES
CHEMICAL COMPOSITION
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DEVELOPED COUNTRIES
DIAGENESIS
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