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Bohrmann, Gerhard (2004): (Table 1) Chemical and isotopic composition of pore fluids in cores TGC-1 and TGC-6. doi:10.1594/PANGAEA.770007,
Supplement to: Aloisi, Giovanni; Wallmann, Klaus; Drews, Manuela; Bohrmann, Gerhard (2004): Evidence for the submarine weathering of silicate minerals in Black Sea sediments: possible implications for the marine Li and B cycles. Geochemistry, Geophysics, Geosystems, 5(1), Q04007, doi:10.1029/2003GC000639

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Abstract:
The role of sediment diagenesis in the marine cycles of Li and B is poorly understood. Because Li and B are easily mobilized during burial and are consumed in authigenic clay mineral formation, their abundance in marine pore waters varies considerably. Exchange with the overlying ocean through diffusive fluxes should thus be common. Nevertheless, only a minor Li sink associated with the low-temperature alteration of volcanic ash has been observed. We describe a low-temperature diagenetic environment in the Black Sea dominated by the alteration of detrital plagioclase feldspars. Fluids expelled from the Odessa mud volcano in the Sorokin Trough originate from shallow (~100-400 m deep) sediments which are poor in volcanic materials but rich in anorthite. These fluids are depleted in Na+, K+, Li+, B, and 18O and enriched in Ca2+ and Sr2+, indicating that anorthite is dissolving and authigenic clays are forming. Using a simple chemical model, we calculate the pH and the partial pressure of CO2 (PCO2) in fluids associated with this alteration process. Our results show that the pH of these fluids is up to 1.5 pH units lower than in most deep marine sediments and that PCO2 levels are up to several hundred times higher than in the atmosphere. These conditions are similar to those which favor the weathering of silicate minerals in subaerial soil environments. We propose that in Black Sea sediments enhanced organic matter preservation favors CO2 production through methanogenesis and results in a low pore water pH, compared to most deep sea sediments. As a result, silicate mineral weathering, which is a sluggish process in most marine diagenetic environments, proceeds rapidly in Black Sea sediments. There is a potential for organic matter-rich continental shelf environments to host this type of diagenesis. Should such environments be widespread, this new Li and B sink could help balance the marine Li and Li isotope budgets but would imply an apparent imbalance in the B cycle.
Coverage:
Median Latitude: 44.308667 * Median Longitude: 35.067750 * South-bound Latitude: 44.233833 * West-bound Longitude: 34.980833 * North-bound Latitude: 44.383500 * East-bound Longitude: 35.154667
Date/Time Start: 2002-01-09T16:33:00 * Date/Time End: 2002-01-18T03:24:00
Minimum DEPTH, sediment/rock: 0.025 m * Maximum DEPTH, sediment/rock: 3.600 m
Event(s):
M52/1_18 (TGC-1) * Latitude: 44.383500 * Longitude: 35.154667 * Date/Time Start: 2002-01-09T16:33:00 * Date/Time End: 2002-01-09T17:50:00 * Elevation: -1836.0 m * Recovery: 4.1 m * Location: Black Sea * Campaign: M52/1 * Basis: Meteor (1986) * Device: Thermistor Gravity Corer (TGC) * Comment: many gas hydrates in thin layers
M52/1_39 (TGC-6) * Latitude: 44.233833 * Longitude: 34.980833 * Date/Time Start: 2002-01-18T01:56:00 * Date/Time End: 2002-01-18T03:24:00 * Elevation: -2161.0 m * Recovery: 3.1 m * Location: Black Sea * Campaign: M52/1 * Basis: Meteor (1986) * Device: Thermistor Gravity Corer (TGC) * Comment: no gas hydrates
Parameter(s):
#NameShort NameUnitPrincipal InvestigatorMethodComment
1Event labelEvent
2DEPTH, sediment/rockDepthmGeocode
3SodiumNammol/lAloisi, GiovanniIon chromatography and optical ICP
4ChlorideCl-mmol/lAloisi, GiovanniIon chromatography and optical ICP
5MagnesiumMgmmol/lAloisi, GiovanniIon chromatography and optical ICP
6Sulfate[SO4]2-mmol/lAloisi, GiovanniIon chromatography and optical ICP
7PotassiumKmmol/lAloisi, GiovanniIon chromatography and optical ICP
8SiliconSiµmol/lAloisi, GiovanniIon chromatography and optical ICP
9BoronBµmol/lAloisi, GiovanniIon chromatography and optical ICP
10LithiumLiµmol/lAloisi, GiovanniIon chromatography and optical ICP
11CalciumCammol/lAloisi, GiovanniIon chromatography and optical ICP
12StrontiumSrµmol/lAloisi, GiovanniIon chromatography and optical ICP
13BariumBaµmol/lAloisi, GiovanniIon chromatography and optical ICP
14Ammonium[NH4]+µmol/lAloisi, GiovanniIon chromatography and optical ICP
15SulfideS2-µmol/lAloisi, GiovanniIon chromatography and optical ICPHS
16BromineBrµmol/lAloisi, GiovanniIon chromatography and optical ICP
17IodineIµmol/lAloisi, GiovanniIon chromatography and optical ICP
18delta 18O, waterd18O H2Oper mil SMOWAloisi, Giovanni
19Alkalinity, totalATmmol(eq)/kgAloisi, GiovanniTitration
20pHpHAloisi, GiovanniMeasured
21pHpHAloisi, Giovannimodelled
22Carbon dioxide, partial pressurepCO2µatmAloisi, Giovannimodelled
Size:
666 data points

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