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| Titel |
Geophysical and geochemical signatures of Gulf of Mexico seafloor brines |
| VerfasserIn |
S. B. Joye, I. R. MacDonald, J. P. Montoya, M. Peccini |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 2, no. 3 ; Nr. 2, no. 3 (2005-10-28), S.295-309 |
| Datensatznummer |
250000624
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| Publikation (Nr.) |
 copernicus.org/bg-2-295-2005.pdf |
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| Zusammenfassung |
| Geophysical, temperature, and discrete depth-stratified geochemical data
illustrate differences between an actively venting mud volcano and a
relatively quiescent brine pool in the Gulf of Mexico along the continental
slope. Geophysical data, including laser-line scan mosaics and sub-bottom
profiles, document the dynamic nature of both environments. Temperature
profiles, obtained by lowering a CTD into the brine fluid, show that the
venting brine was at least 10°C warmer than the bottom water. At the
brine pool, thermal stratification was observed and only small differences
in stratification were documented between three sampling times (1991, 1997
and 1998). In contrast, at the mud volcano, substantial temperature
variability was observed, with the core brine temperature being slightly
higher than bottom water (by 2°C) in 1997 but substantially higher than
bottom water (by 19°C) in 1998. Detailed geochemical samples were
obtained in 2002 using a device called the "brine trapper" and
concentrations of dissolved gases, major ions and nutrients were determined.
Both brines contained about four times as much salt as seawater and steep
concentration gradients of dissolved ions and nutrients versus brine depth
were apparent. Differences in the concentrations of calcium, magnesium and
potassium between the two brine fluids suggest that the fluids are derived
from different sources, have different dilution/mixing histories, or that
brine-sediment reactions are more important at the mud volcano. Substantial
concentrations of methane, ammonium, and silicate were observed in both
brines, suggesting that fluids expelled from deep ocean brines are important
sources of these constituents to the surrounding environment. |
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