Is methane venting at the seafloor recorded by δ13C of benthic foraminifera shells?

Paleoceanography - Tập 18 Số 3 - 2003
Marta E. Torres1, Alan C Mix1, K. Kinports1, Brian A. Haley1, G. P. Klinkhammer1, James McManus1, Marie A. de Angelis2
1College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, Oregon, USA
2Department of Oceanography, Humboldt State University, Arcata, California, USA

Tóm tắt

The isotopic composition of the dissolved inorganic carbon (DIC) collected at sites of active methane discharge on Hydrate Ridge, Oregon, reveals anaerobic methane oxidation mediated by bacteria, with δ13CDIC reaching values as low as −48‰ in the upper 4 cm of the sediment. In spite of the high sulfide levels in the discharging fluids, living specimens of the benthic foraminifera Uvigerina peregrina are abundant in the vents, probably owing to the rich bacterial food source. Although pore water δ13CDIC is extremely low (−6 to −48‰), the δ13C values of living (Rose Bengal stained) foraminifera shells collected from active methane seeps are not significantly lower than those observed in nonventing pelagic sediments, and are within the range expected from local organic matter decomposition (0 to −4‰). The apparent δ13C disequilibrium between biogenic calcite and DIC suggests that at seep localities, foraminifera calcify mostly during periods when there is little methane discharge or during intermittent episodes of seawater flow into the sediments. The isotopic composition and Mg/Ca ratios of fossil (unstained) foraminifera recovered at carbonate‐rich sites on the northern Hydrate Ridge reveals overprinting of the biogenic record by inorganic calcite with high Mg/Ca and anomalously low δ13C values. Thus overprinting of the original isotopic composition of foraminifera by overgrowths or recrystallization at or below the sediment surface, rather than primary calcification in contact with 13C depleted DIC, can explain extreme 13C depletion observed in fossil foraminifera recovered from sites of active methane discharge.

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Tài liệu tham khảo

Aharon P. M.Ilackworth E.Platon C.Wheeler andB.Sen Gupta Isotope records of recent benthic foraminifera from hydrate‐bearing sediments: Methane‐hydrate dissociation effects paper presented atGSA Annual Meeting Geol. Soc. of Am. Boulder Colo. 2001.

10.1016/0377-8398(92)90024-E

10.1029/2001PA000672

10.1016/0198-0149(92)90090-G

10.1007/BF00003221

10.1016/S0967-0637(01)00017-6

10.1038/35036572

10.1130/0091-7613(1998)026<0647:ACFTCS>2.3.CO;2

10.1016/0012-821X(81)90022-4

10.1130/0091-7613(1999)027<0063:BRTLQR>2.3.CO;2

10.1016/0198-0149(90)90015-N

10.1029/95PA02087

10.1130/0091-7613(1997)025<0259:ABOGIT>2.3.CO;2

Field M. E., 1987, Preliminary report on gaseous hydrocarbons in sediment and seeps, offshore Eel River Basin, California, San Joaquin, Geol. Soc. Misc. Publ., 37, 55

Greinert J. Rezente submarine Mineralbildungen: Abbild geochemischer Prozesse an aktiven Fluidaustrittsstellen im Aleuten‐ und Cascadia‐Akkretionskomplex Ph.D. dissertation GEOMAR Rep. 87 21 pp. Univ. of Kiel Kiel Germany 1999.

10.1016/S0009-2541(01)00399-0

10.1016/0016-7037(79)90029-2

10.1016/0304-4203(82)90047-0

10.1016/0045-6535(93)90442-8

10.1029/96PA01021

10.1128/MMBR.44.4.739-796.1980

10.1126/science.288.5463.128

10.4319/lo.1989.34.3.0635

10.1016/S0031-0182(99)00065-6

10.1029/01EO00275

10.1126/science.287.5451.269

10.1130/0091-7613(1994)022<0699:GHTBTS>2.3.CO;2

10.1130/0091-7613(1994)022<0459:OOBSRG>2.3.CO;2

10.1016/S0377-8398(00)00040-2

10.1111/j.1749-6632.2000.tb06847.x

10.1016/S0012-821X(99)00116-8

10.1029/PA005i002p00161

10.1016/S0967-0637(97)00004-6

10.1007/978-1-4615-4197-4_13

10.1016/0016-7037(95)00446-7

10.1016/S0016-7037(96)00256-6

10.1029/96PA03165

10.1029/1999GB001155

10.1016/S0377-8398(00)00005-0

10.3354/meps231121

10.2113/gsjfr.27.4.292

Sen Gupta B. K. E.Platon M. S.Hackworth andP.Aharon Historical record of benthic foraminiferal species at a methane‐hydrate dissociation site Green Canyon Gulf of Mexico paper presented atGSA Annual Meeting Geol. Soc. of Am. Boulder Colo. 5 – 8 Nov.2001.

10.1029/2001GC000196

10.1016/0031-0182(89)90033-3

10.1016/S0012-821X(99)00092-8

10.1029/GM124p0087

Thomas E., 1998, The Paleocene/Eocene Boundary (IGCP Project 308), 214

Torres M. E. G.Bohrmann K.Brown M. A.de Angelis D.Hammond G.Klinkhammer J.McManus E.Suess andA.Trehu Geochemical observations on Hydrate Ridge Cascadia Margin during R/V‐ATLANTIS‐cruise aT3‐35b July 1999 COAS Data Rep. 174 Ref. 99‐3 Oreg. St. Univ. Corvallis Oreg. 1999.

10.1016/S0012-821X(02)00733-1

10.1130/0091-7613(1999)027<0939:TASEOA>2.3.CO;2

A. M. Trehu N. L. Bangs M. A. Arsenault G. Bohrmann C. Goldfinger J. E. Johnson Y. Nakamura M. E. Torres 2002 90 96

10.1130/0091-7613(1999)027<1075:MOTADF>2.3.CO;2

10.1016/S0012-821X(02)00732-X

10.1038/369282a0

Zonenshayn L. P., 1987, An underwater gas source in the Sea of Okhotsk West of Paramushir Island, Oceanology, 27, 598

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Paleoceanography

Tập 18 Số 3

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