Chemical and isotopic evidence of gas‐influenced flow at a transform plate boundary: Monterey Bay, California

Martin, Jonathan B.; Orange, Daniel L.; Lorenson, Thomas D.; Kvenvolden, Keith A.

doi:10.1029/97jb02154

Cited by 21 publications

(23 citation statements)

References 40 publications

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“…These differences in beam intensities indicate larger foraminifera were collected from within the seep sites than nonseep sites, and thus the overall lower δ 13 C test values observed for foraminifera within the seeps are not a result of an artifact of blank contamination from small samples or fractionation to lighter isotopes in small foraminifera [e.g., McCorkle et al , 2008]. The isotopically lighter values of seep foraminifera are far from equilibrium with δ 13 C DIC values of the pore waters, which are as low as about −40‰ [ Martin et al , 1997]. The isotopic values of the nonseep specimens are similar to values found elsewhere.…”

Section: Discussionmentioning

confidence: 99%

Combined carbonate carbon isotopic and cellular ultrastructural studies of individual benthic foraminifera: Method description

et al. 2010

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[1] Carbon isotopes of foraminiferal tests provide a widely used proxy for past oceanographic environmental conditions. This proxy can be calibrated using live specimens, which are reliably identified with observations of cell ultrastructure. Observations of ultrastructures can also be used for studies of biological characteristics such as diet and presence of symbionts. Combining biological and isotopic studies on individual foraminifera could provide novel information, but standard isotopic methods destroy ultrastructures by desiccating specimens and observations of ultrastructure require removal of carbonate tests, preventing isotope measurements. The approach described here preserves cellular ultrastructure during isotopic analyses by keeping the foraminifera in an aqueous buffer (Phosphate Buffered Saline (PBS)). The technique was developed and standardized with 36 aliquots of NBS-19 standard of similar weight to foraminiferal tests (5 to 123 mg). Standard errors ranged from ± 0.06 to ± 0.85‰ and were caused by CO 2 contaminants dissolved in the PBS. The technique was used to measure d 13 C values of 96 foraminifera, 10 of which do not precipitate carbonate tests. Calcareous foraminiferal tests had corrected carbon isotope ratios of −8.5 to +3.2‰. This new technique allows comparisons of isotopic compositions of tests made by foraminifera known to be alive at the time of collection with their biological characteristics such as prey composition and presence or absence of putative symbionts. The approach may be applied to additional biomineralizing organisms such as planktonic foraminifera, pteropods, corals, and coccolithophores to elucidate certain biological controls on their paleoceanographic proxy signatures.

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Section: Discussionmentioning

confidence: 99%

Combined carbonate carbon isotopic and cellular ultrastructural studies of individual benthic foraminifera: Method description

et al. 2010

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“…Previous studies of the pore water chemistry at cold seep sites in Monterey Bay have shown that fluids at most sites are enriched in sulfide, methane and CO 2 [ Barry et al , 1997; Gieskes et al , 2005; Martin et al , 1997]. Low δ 13 C DIC (dissolved inorganic carbon) values in the pore waters result from the production of 13 C‐depleted bicarbonate by anaerobic oxidation of ascending methane.…”

Section: Hydrogeologymentioning

confidence: 99%

“…Low δ 13 C DIC (dissolved inorganic carbon) values in the pore waters result from the production of 13 C‐depleted bicarbonate by anaerobic oxidation of ascending methane. Furthermore, low δ 13 C CH4 values (<−70‰ [ Martin et al , 1997]) suggest that methane in Monterey Bay pore fluid samples is largely of microbial origin. However, there seems to be a distinctive contribution of a thermogenic methane component at some seeps, most likely derived from the organic‐rich Monterey Formation or Santa Cruz Mudstone [ Lorenson et al , 2002; Martin et al , 1997; Stakes et al , 1999].…”

Section: Hydrogeologymentioning

confidence: 99%

“…Furthermore, low δ 13 C CH4 values (<−70‰ [ Martin et al , 1997]) suggest that methane in Monterey Bay pore fluid samples is largely of microbial origin. However, there seems to be a distinctive contribution of a thermogenic methane component at some seeps, most likely derived from the organic‐rich Monterey Formation or Santa Cruz Mudstone [ Lorenson et al , 2002; Martin et al , 1997; Stakes et al , 1999]. Furthermore, the thermogenic hydrocarbon component suggests potential input of deep fluid from >∼2 km depth (assuming a geothermal gradient of ∼50°C/km and a temperature of 100°C required for thermal degradation of organic matter) [ Martin et al , 1997].…”

Section: Hydrogeologymentioning

confidence: 99%

“…However, there seems to be a distinctive contribution of a thermogenic methane component at some seeps, most likely derived from the organic‐rich Monterey Formation or Santa Cruz Mudstone [ Lorenson et al , 2002; Martin et al , 1997; Stakes et al , 1999]. Furthermore, the thermogenic hydrocarbon component suggests potential input of deep fluid from >∼2 km depth (assuming a geothermal gradient of ∼50°C/km and a temperature of 100°C required for thermal degradation of organic matter) [ Martin et al , 1997]. A deep origin of some seep fluids has also been suggested by Rathburn et al [2003] on the basis of elevated concentrations of chloride, calcium, and lithium in pore fluids.…”

Section: Hydrogeologymentioning

confidence: 99%

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Helium systematics of cold seep fluids at Monterey Bay, California, USA: Temporal variations and mantle contributions

Füri

Hilton

Brown

et al. 2009

Geochem Geophys Geosyst

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[1] We report helium isotope ratios ( 3 He/ 4 He) as well as helium and neon abundance results for submarine cold seep fluids from Extrovert Cliff in Monterey Bay, California. Samples were collected in copper tubing attached to submarine flux meters operating in continuous pumping mode. Following instrumentation recovery, the tubing was sectioned to produce for the first time a high-resolution time series of dissolved He and Ne variations over a time span of several days. Noble gas concentrations are variable and appear affected by interaction with a hydrocarbon phase within the aquifer. However, it is still possible to resolve the He signal into components associated with air equilibration, excess air entrainment, and terrigenic fluxes (both crustal and mantle-derived). The mantle He contribution reaches $25-30% in some samples (up to 2.3 R A , where R A = air 3 He/ 4 He). Our quasi-continuous He-Ne record shows remarkable fluctuations over time scales of only a few hours and reflects the combined effects of gas stripping by hydrocarbons and an episodic input of mantle-derived fluids.

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Cold seeps in Monterey Bay, California: Geochemistry of pore waters and relationship to benthic foraminiferal calcite

Gieskes

Rathburn

Martin

et al. 2011

Applied Geochemistry

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Chemical and isotopic evidence of gas‐influenced flow at a transform plate boundary: Monterey Bay, California

Cited by 21 publications

References 40 publications

Combined carbonate carbon isotopic and cellular ultrastructural studies of individual benthic foraminifera: Method description

Combined carbonate carbon isotopic and cellular ultrastructural studies of individual benthic foraminifera: Method description

Helium systematics of cold seep fluids at Monterey Bay, California, USA: Temporal variations and mantle contributions

Cold seeps in Monterey Bay, California: Geochemistry of pore waters and relationship to benthic foraminiferal calcite

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