Fatty acids in sparry calcite fracture fills and microsparite cement of septarian diagenetic concretions

M J Pearson, J P Hendry, C W Taylor, A A Russell

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

Sparry calcite fracture fills and concretion body cements in concretions from the Flodigarry Shale Member of the Staffin Shale Formation, Isle of Skye, Scotland, entrap and preserve mineral and organic materials of sedimentary and diagenetic origin. Fatty acids are a major component of the lipids recovered by decarbonation and comprise mainly n-alkanoic and alpha-omega dicarboxylic acids. Two generations of fracture-fill calcite (early brown and later yellow) and the concretion body microspar yield significantly different fatty acid profiles. Early brown calcites yield mainly medium-chain n-alkanoic acids with strong even predominance; later yellow calcites are dominated by alpha-omega dicarboxylic acids with no even predominance. Both fracture fills lack the long-chain n-alkanoic and alpha-omega dicarboxylic acids additionally recovered from the concretion bodies. The absence of longer chain acids in the calcite spar fracture fills is inferred to result from the transport of fatty acids by septarian mineralising fluids whereby low-aqueous solubility of longer chain acids or their salts accounts for their relative immobility.

Comparative experiments have been carried out using conventional solvent extraction on the concretion body and associated shales, both decarbonated and untreated. Extracted lipid yields are higher, but the fatty acids probably derive from mixed locations in the rock including both kerogen- and carbon ate-associated lipid pools. Only experiments involving decarbonation yielded alpha-omega dicarboxylic acids in molecular distributions probably controlled mainly by fluid transport. Alkane biomarker ratios indicate very low thermal maturity has been experienced by the concretions and their host sediments. Septarian cracks lined by brown calcite formed during early burial. Microbial CO2 from sulphate-reducing bacteria was probably the main source of mineralising carbonate. Emplacement of the later septarian fills probably involved at least one episode of fluid invasion. Copyright (c) 2005 Elsevier Ltd.

Original languageEnglish
Pages (from-to)1773-1786
Number of pages14
JournalGeochimica et Cosmochimica Acta
Volume69
DOIs
Publication statusPublished - 2005

Keywords

  • SULFATE-REDUCING BACTERIA
  • RIVER OIL-SHALE
  • ORGANIC-MATTER
  • CARBONATE CONCRETIONS
  • HYDROXY-ACIDS
  • GEOCHEMICAL SIGNIFICANCE
  • DICARBOXYLIC-ACIDS
  • ISOTOPIC EVIDENCE
  • MARINE-SEDIMENTS
  • CARBOXYLIC-ACIDS

Cite this

Fatty acids in sparry calcite fracture fills and microsparite cement of septarian diagenetic concretions. / Pearson, M J ; Hendry, J P ; Taylor, C W ; Russell, A A .

In: Geochimica et Cosmochimica Acta, Vol. 69, 2005, p. 1773-1786.

Research output: Contribution to journalArticle

Pearson, M J ; Hendry, J P ; Taylor, C W ; Russell, A A . / Fatty acids in sparry calcite fracture fills and microsparite cement of septarian diagenetic concretions. In: Geochimica et Cosmochimica Acta. 2005 ; Vol. 69. pp. 1773-1786.
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T1 - Fatty acids in sparry calcite fracture fills and microsparite cement of septarian diagenetic concretions

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AU - Hendry, J P

AU - Taylor, C W

AU - Russell, A A

PY - 2005

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N2 - Sparry calcite fracture fills and concretion body cements in concretions from the Flodigarry Shale Member of the Staffin Shale Formation, Isle of Skye, Scotland, entrap and preserve mineral and organic materials of sedimentary and diagenetic origin. Fatty acids are a major component of the lipids recovered by decarbonation and comprise mainly n-alkanoic and alpha-omega dicarboxylic acids. Two generations of fracture-fill calcite (early brown and later yellow) and the concretion body microspar yield significantly different fatty acid profiles. Early brown calcites yield mainly medium-chain n-alkanoic acids with strong even predominance; later yellow calcites are dominated by alpha-omega dicarboxylic acids with no even predominance. Both fracture fills lack the long-chain n-alkanoic and alpha-omega dicarboxylic acids additionally recovered from the concretion bodies. The absence of longer chain acids in the calcite spar fracture fills is inferred to result from the transport of fatty acids by septarian mineralising fluids whereby low-aqueous solubility of longer chain acids or their salts accounts for their relative immobility.Comparative experiments have been carried out using conventional solvent extraction on the concretion body and associated shales, both decarbonated and untreated. Extracted lipid yields are higher, but the fatty acids probably derive from mixed locations in the rock including both kerogen- and carbon ate-associated lipid pools. Only experiments involving decarbonation yielded alpha-omega dicarboxylic acids in molecular distributions probably controlled mainly by fluid transport. Alkane biomarker ratios indicate very low thermal maturity has been experienced by the concretions and their host sediments. Septarian cracks lined by brown calcite formed during early burial. Microbial CO2 from sulphate-reducing bacteria was probably the main source of mineralising carbonate. Emplacement of the later septarian fills probably involved at least one episode of fluid invasion. Copyright (c) 2005 Elsevier Ltd.

AB - Sparry calcite fracture fills and concretion body cements in concretions from the Flodigarry Shale Member of the Staffin Shale Formation, Isle of Skye, Scotland, entrap and preserve mineral and organic materials of sedimentary and diagenetic origin. Fatty acids are a major component of the lipids recovered by decarbonation and comprise mainly n-alkanoic and alpha-omega dicarboxylic acids. Two generations of fracture-fill calcite (early brown and later yellow) and the concretion body microspar yield significantly different fatty acid profiles. Early brown calcites yield mainly medium-chain n-alkanoic acids with strong even predominance; later yellow calcites are dominated by alpha-omega dicarboxylic acids with no even predominance. Both fracture fills lack the long-chain n-alkanoic and alpha-omega dicarboxylic acids additionally recovered from the concretion bodies. The absence of longer chain acids in the calcite spar fracture fills is inferred to result from the transport of fatty acids by septarian mineralising fluids whereby low-aqueous solubility of longer chain acids or their salts accounts for their relative immobility.Comparative experiments have been carried out using conventional solvent extraction on the concretion body and associated shales, both decarbonated and untreated. Extracted lipid yields are higher, but the fatty acids probably derive from mixed locations in the rock including both kerogen- and carbon ate-associated lipid pools. Only experiments involving decarbonation yielded alpha-omega dicarboxylic acids in molecular distributions probably controlled mainly by fluid transport. Alkane biomarker ratios indicate very low thermal maturity has been experienced by the concretions and their host sediments. Septarian cracks lined by brown calcite formed during early burial. Microbial CO2 from sulphate-reducing bacteria was probably the main source of mineralising carbonate. Emplacement of the later septarian fills probably involved at least one episode of fluid invasion. Copyright (c) 2005 Elsevier Ltd.

KW - SULFATE-REDUCING BACTERIA

KW - RIVER OIL-SHALE

KW - ORGANIC-MATTER

KW - CARBONATE CONCRETIONS

KW - HYDROXY-ACIDS

KW - GEOCHEMICAL SIGNIFICANCE

KW - DICARBOXYLIC-ACIDS

KW - ISOTOPIC EVIDENCE

KW - MARINE-SEDIMENTS

KW - CARBOXYLIC-ACIDS

U2 - 10.1016/j.gca.2004.09.024

DO - 10.1016/j.gca.2004.09.024

M3 - Article

VL - 69

SP - 1773

EP - 1786

JO - Geochimica et Cosmochimica Acta

JF - Geochimica et Cosmochimica Acta

SN - 0016-7037

ER -