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Eickmann, Benjamin; Bach, Wolfgang; Peckmann, Jörn Ludwig (2009): (Table 1) List of samples with carbonate mineralogy, stable isotope, and accessory-mineral information. PANGAEA, https://doi.org/10.1594/PANGAEA.746417, Supplement to: Eickmann, B et al. (2009): Authigenesis of carbonate minerals in modern and Devonian ocean-floor hard rocks. The Journal of Geology, 117, 307-323, https://doi.org/10.1086/597362

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Abstract:
Petrographic and stable-isotope (d13C, d18O) patterns of carbonates from the Logatchev Hydrothermal Field (LHF), the Gakkel Ridge (GR), and a Late Devonian outcrop from the Frankenwald (Germany) were compared in an attempt to understand the genesis of carbonate minerals in marine volcanic rocks. Specifically, were the carbonate samples from modern sea floor settings and the Devonian analog of hydrothermal origin, low-temperature abiogenic origin (as inferred for aragonite in serpentinites from elsewhere on the Mid-Atlantic Ridge), or biogenic origin? Aragonite is the most abundant carbonate mineral in serpentinites from the two modern spreading ridges and occurs within massive sulfides of the LHF. The precipitation and preservation of aragonite suggests high Mg2+ and sulfate concentrations in fluids. Values of d18OPDB as high as +5.3 per mill for serpentinite-hosted aragonite and as high as +4.2 per mill for sulfide-hosted aragonite are consistent with precipitation from cold seawater. Most of the corresponding d13C values indicate a marine carbon source, whereas d13C values for sulfide-hosted aragonite as high as +3.6 per mill may reflect residual carbon dioxide in the zone of methanogenesis. Calcite veins from the LHF, by contrast, have low d18OPDB (-20.0 per mill to -16.1 per mill) and d13C values (-5.8 per mill to -4.5 per mill), indicative of precipitation from hydrothermal solutions (~129°-186°C) dominated by magmatic CO2. Calcite formation was probably favored by fluid rock interactions at elevated temperatures, which tend to remove solutes that inhibit calcite precipitation in seawater (Mg2+ and sulfate). Devonian Frankenwald calcites show low d18O values, reflecting diagenetic and metamorphic overprinting. Values of d13C around 0 per mill for basalt-hosted calcite indicate seawater-derived inorganic carbon, whereas d13C values for serpentinite-hosted calcite agree with mantle-derived CO2 (for values as low as -6 per mill) with a contribution of amagmatic carbon (for values as low as -8.6 per mill), presumably methane. Secondary mineral phases from the LHF for which a biogenic origin appears feasible include dolomite dumbbells, clotted carbonate, and a network of iron- and silica-rich filaments.
Coverage:
Median Latitude: 41.169851 * Median Longitude: -21.903537 * South-bound Latitude: 14.711667 * West-bound Longitude: -45.923642 * North-bound Latitude: 85.375000 * East-bound Longitude: 14.995000
Date/Time Start: 2001-08-20T02:03:00 * Date/Time End: 2004-02-04T00:00:00
Minimum Elevation: -4043.0 m * Maximum Elevation: -1938.0 m
Event(s):
FW-05-S * Latitude: 50.169200 * Longitude: 11.527100 * Location: Frankenwald, northern Bavaria, Germany * Method/Device: Geological sample (GEOS)
M60/3-49-GTV * Latitude Start: 14.940078 * Longitude Start: -44.919914 * Latitude End: 14.940078 * Longitude End: -44.920931 * Date/Time: 2004-01-29T00:00:00 * Elevation Start: -3293.0 m * Elevation End: -3314.0 m * Location: Mid-Atlantic Ridge at 10-15°N * Campaign: M60/3 (HYDROMAR1) * Basis: Meteor (1986) * Method/Device: Television-Grab (TVG) * Comment: Working Area II
M60/3-53-ROV-2 * Latitude: 14.751758 * Longitude: -44.978367 * Date/Time: 2004-01-30T17:17:00 * Elevation: -2978.0 m * Location: Mid-Atlantic Ridge at 10-15°N * Campaign: M60/3 (HYDROMAR1) * Basis: Meteor (1986) * Method/Device: Remote operated vehicle (ROV) * Comment: rock sampling
Parameter(s):
#NameShort NameUnitPrincipal InvestigatorMethod/DeviceComment
1Event labelEvent
2Latitude of eventLatitude
3Longitude of eventLongitude
4Elevation of eventElevationm
5Sample IDSample IDEickmann, Benjamin
6Mineral nameMineralEickmann, Benjamin
7Rock typeRockEickmann, Benjamin
8δ13Cδ13C‰ PDBEickmann, BenjaminMass spectrometer Finnigan MAT 251
9δ18Oδ18OEickmann, BenjaminMass spectrometer Finnigan MAT 251
10MineralsMineralsEickmann, Benjamin
Size:
334 data points

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