Methane-related authigenic carbonates from the Black Sea: geochemical characterisation and relation to seeping fluids

A Mazzini, M K Ivanov, J Parnell, A Stadnitskaia, B T Cronin, E Poludetkina, L Mazurenko, T C E van Weering

Research output: Contribution to journalArticle

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Abstract

During TTR11 Cruise (2001), three areas of active fluid venting and mud volcanism were investigated in the Black Sea below the oxic zone at depths varying between 800 and 2200 m. Authigenic carbonates often associated with microbial mats were recovered from the sea floor and the shallow subsurface. Structural and petrographic observations allowed the distinction of five different types of authigenic carbonates; three of these consist of carbonate-cemented layered hemipelagic sedimentary units, while the other two consist of carbonate-cemented mud breccia sediment and authigenic micrite slabs. The carbonate cements consist predominantly of micritic Mg calcite. Their delta(13)C(CaCO3) varies between -8.5parts per thousand and -46.9parts per thousand at the different sampling locations, indicating that authigenic carbonates incorporate variable proportions of carbon derived from the anaerobic oxidation of methane (AOM), the oxidation of organic matter and from sea water. Methane is the dominant component among other hydrocarbon gases in these sediments. Its relative amount varies from 99.9% to 95.1% of total hydrocarbon gases and its delta(13)C values range from congruent to-40parts per thousand to congruent to-74parts per thousand. Methane in sediments associated with the carbonate crusts shows carbon isotopic values 25-30parts per thousand lighter than the authigenic carbonates at all the studied sites, indicating that methane present in the seeping fluids confers a distinct isotopic signature to the carbonate deposits at each location. Models proposed for the formation of carbonate slabs in the subsurface imply methane seepage impeded by homogenous clayey laminae or by pre-existing slabs, coupled with microbial activity oxidising methane and organic matter present in the sediment. Mud breccia crust pavements on the sea floor form by carbonate cementation of methane-charged sediment. Gas saturation of the sediment is confirmed by the presence of gas hydrates, whose shape indicates an association with authigenic carbonates, supporting the idea that sedimentary structures can control gas distribution. (C) 2004 Elsevier B.V. All rights reserved.

Original languageEnglish
Pages (from-to)153-181
Number of pages29
JournalMarine Geology
Volume212
DOIs
Publication statusPublished - 2004

Keywords

  • Black Sea
  • authigenic carbonate
  • hydrocarbon seepage
  • methane and gas hydrates
  • mud volcanism
  • VOLCANO FIELD SEAWARD
  • MUD VOLCANO
  • PORE-WATER
  • ANAEROBIC OXIDATION
  • MEDITERRANEAN SEA
  • SUBDUCTION ZONE
  • CASCADIA MARGIN
  • VENT SITES
  • OXYGEN
  • SEDIMENTS

Cite this

Mazzini, A., Ivanov, M. K., Parnell, J., Stadnitskaia, A., Cronin, B. T., Poludetkina, E., ... van Weering, T. C. E. (2004). Methane-related authigenic carbonates from the Black Sea: geochemical characterisation and relation to seeping fluids. Marine Geology, 212, 153-181. https://doi.org/10.1016/j.margeo.2004.08.001

Methane-related authigenic carbonates from the Black Sea: geochemical characterisation and relation to seeping fluids. / Mazzini, A ; Ivanov, M K ; Parnell, J ; Stadnitskaia, A ; Cronin, B T ; Poludetkina, E ; Mazurenko, L ; van Weering, T C E .

In: Marine Geology, Vol. 212, 2004, p. 153-181.

Research output: Contribution to journalArticle

Mazzini, A, Ivanov, MK, Parnell, J, Stadnitskaia, A, Cronin, BT, Poludetkina, E, Mazurenko, L & van Weering, TCE 2004, 'Methane-related authigenic carbonates from the Black Sea: geochemical characterisation and relation to seeping fluids', Marine Geology, vol. 212, pp. 153-181. https://doi.org/10.1016/j.margeo.2004.08.001
Mazzini, A ; Ivanov, M K ; Parnell, J ; Stadnitskaia, A ; Cronin, B T ; Poludetkina, E ; Mazurenko, L ; van Weering, T C E . / Methane-related authigenic carbonates from the Black Sea: geochemical characterisation and relation to seeping fluids. In: Marine Geology. 2004 ; Vol. 212. pp. 153-181.
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AU - Mazzini, A

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AU - Stadnitskaia, A

AU - Cronin, B T

AU - Poludetkina, E

AU - Mazurenko, L

AU - van Weering, T C E

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N2 - During TTR11 Cruise (2001), three areas of active fluid venting and mud volcanism were investigated in the Black Sea below the oxic zone at depths varying between 800 and 2200 m. Authigenic carbonates often associated with microbial mats were recovered from the sea floor and the shallow subsurface. Structural and petrographic observations allowed the distinction of five different types of authigenic carbonates; three of these consist of carbonate-cemented layered hemipelagic sedimentary units, while the other two consist of carbonate-cemented mud breccia sediment and authigenic micrite slabs. The carbonate cements consist predominantly of micritic Mg calcite. Their delta(13)C(CaCO3) varies between -8.5parts per thousand and -46.9parts per thousand at the different sampling locations, indicating that authigenic carbonates incorporate variable proportions of carbon derived from the anaerobic oxidation of methane (AOM), the oxidation of organic matter and from sea water. Methane is the dominant component among other hydrocarbon gases in these sediments. Its relative amount varies from 99.9% to 95.1% of total hydrocarbon gases and its delta(13)C values range from congruent to-40parts per thousand to congruent to-74parts per thousand. Methane in sediments associated with the carbonate crusts shows carbon isotopic values 25-30parts per thousand lighter than the authigenic carbonates at all the studied sites, indicating that methane present in the seeping fluids confers a distinct isotopic signature to the carbonate deposits at each location. Models proposed for the formation of carbonate slabs in the subsurface imply methane seepage impeded by homogenous clayey laminae or by pre-existing slabs, coupled with microbial activity oxidising methane and organic matter present in the sediment. Mud breccia crust pavements on the sea floor form by carbonate cementation of methane-charged sediment. Gas saturation of the sediment is confirmed by the presence of gas hydrates, whose shape indicates an association with authigenic carbonates, supporting the idea that sedimentary structures can control gas distribution. (C) 2004 Elsevier B.V. All rights reserved.

AB - During TTR11 Cruise (2001), three areas of active fluid venting and mud volcanism were investigated in the Black Sea below the oxic zone at depths varying between 800 and 2200 m. Authigenic carbonates often associated with microbial mats were recovered from the sea floor and the shallow subsurface. Structural and petrographic observations allowed the distinction of five different types of authigenic carbonates; three of these consist of carbonate-cemented layered hemipelagic sedimentary units, while the other two consist of carbonate-cemented mud breccia sediment and authigenic micrite slabs. The carbonate cements consist predominantly of micritic Mg calcite. Their delta(13)C(CaCO3) varies between -8.5parts per thousand and -46.9parts per thousand at the different sampling locations, indicating that authigenic carbonates incorporate variable proportions of carbon derived from the anaerobic oxidation of methane (AOM), the oxidation of organic matter and from sea water. Methane is the dominant component among other hydrocarbon gases in these sediments. Its relative amount varies from 99.9% to 95.1% of total hydrocarbon gases and its delta(13)C values range from congruent to-40parts per thousand to congruent to-74parts per thousand. Methane in sediments associated with the carbonate crusts shows carbon isotopic values 25-30parts per thousand lighter than the authigenic carbonates at all the studied sites, indicating that methane present in the seeping fluids confers a distinct isotopic signature to the carbonate deposits at each location. Models proposed for the formation of carbonate slabs in the subsurface imply methane seepage impeded by homogenous clayey laminae or by pre-existing slabs, coupled with microbial activity oxidising methane and organic matter present in the sediment. Mud breccia crust pavements on the sea floor form by carbonate cementation of methane-charged sediment. Gas saturation of the sediment is confirmed by the presence of gas hydrates, whose shape indicates an association with authigenic carbonates, supporting the idea that sedimentary structures can control gas distribution. (C) 2004 Elsevier B.V. All rights reserved.

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KW - methane and gas hydrates

KW - mud volcanism

KW - VOLCANO FIELD SEAWARD

KW - MUD VOLCANO

KW - PORE-WATER

KW - ANAEROBIC OXIDATION

KW - MEDITERRANEAN SEA

KW - SUBDUCTION ZONE

KW - CASCADIA MARGIN

KW - VENT SITES

KW - OXYGEN

KW - SEDIMENTS

U2 - 10.1016/j.margeo.2004.08.001

DO - 10.1016/j.margeo.2004.08.001

M3 - Article

VL - 212

SP - 153

EP - 181

JO - Marine Geology

JF - Marine Geology

SN - 0025-3227

ER -