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| Titel |
Sulfate reduction in a pockmark field on the Chatham Rise, New Zealand |
| VerfasserIn |
Paula Rose, Richard Coffin, Lewis Millholland, Ingo Klaucke, Jörg Bialas, Ingo Pecher, Andrew Gorman |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250074913
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| Zusammenfassung |
| Seismic studies have identified an extensive field (>20,000 km2) of seafloor depressions, or
pockmarks, on the southwestern flank of the Chatham Rise, New Zealand. It has been
suggested that these pockmarks result from gas hydrate dissociation linked to sea-level
changes during glacial-interglacial cycles. Gas hydrates are predominately composed of
methane (CH4), a potent greenhouse gas. The upward flux of CH4 in sediments is often
quantified using pore water sulfate (SO42-) profiles, assuming steady-state consumption of
SO42- and CH4 by anaerobic oxidation of methane (AOM): CH4 + SO42- - HCO3- +
HS- + H2O. This reaction is one of the primary controls on CH4 distributions in
sediments.
Surface sediment cores (~ 8 m) will be collected from the pockmark field on the
Chatham Rise during a research cruise in February 2013 to evaluate the association of the
features with CH4 releases. A suite of geochemical parameters will be determined in both
solid phase sediment and pore water. This work will present pore water SO42-, sulfide
(HS-) and chloride (Cl-) depth profiles in sediments collected from the pockmark
field. Theoretical SO42- distributions in the absence of AOM will be compared to
observed SO42-profiles as a preliminary assessment of the influence of CH4 on
sediment geochemistry in and around the seafloor depressions. Chloride and HS-
distributions will further elucidate the role of gas hydrate dissociation at these sites and its
possible role in the formation of the pockmarks on the Chatham Rise. These data
will provide the foundation for interpreting CH4 profiles in the same sediments
and will generally lead to a better understanding of sediment CH4geochemistry. |
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