Stein, C L; Smith, A J (1986): Carbonate aggregate mineralogy and stable isotopes at DSDP Site 87-583. PANGAEA, https://doi.org/10.1594/PANGAEA.801635, Supplement to: Stein, CL; Smith, AJ (1986): Authigenic carbonate nodules in the Nankai Trough, Site 583. In: Kagami, H; Karig, DE; Coulbourn, WT; et al. (eds.), Initial Reports of the Deep Sea Drilling Project, Washington (U.S. Govt. Printing Office), 87, 659-668, https://doi.org/10.2973/dsdp.proc.87.115.1986
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Crystalline aggregates composed of calcium carbonate were recovered in the uppermost 50 m of Nankai Trough sediments during DSDP Leg 87A. These aggregates decomposed with time to masses of sandy calcite as determined by X-ray diffraction analysis. Petrographic and scanning electron microscopy revealed textures suggestive of a precursor phrase prior to calcite, and this precursor has been tentatively identified as the mineral ikaite, CaCO3*6H2O. Stable isotope data suggest a large component of terrigenous organic matter as the carbon source, consistent with the appearance of these aggregates in highly reducing pyritic sediments containing abundant plant remains. We propose that these nodules formed in euxinic basins on the upper part of the Trough slope under normal seafloor conditions of pressure and temperature. Calculated temperatures of formation of this phase are not unusually low. The specimens from Site 583 are the first reported occurrences of ikaite in active margin sediments.
Median Latitude: 31.831280 * Median Longitude: 133.854620 * South-bound Latitude: 31.830000 * West-bound Longitude: 133.854300 * North-bound Latitude: 31.836300 * East-bound Longitude: 133.856700
Date/Time Start: 1982-07-08T00:00:00 * Date/Time End: 1982-07-08T00:00:00
Datasets listed in this publication series
- Stein, CL; Smith, AJ (1986): (Table 1) Carbonate aggregate mineralogy at DSDP at DSDP Sample 87-583C-2-1,71-72. https://doi.org/10.1594/PANGAEA.801633
- Stein, CL; Smith, AJ (1986): (Table 2) Stable isotopes at DSDP Site 87-583. https://doi.org/10.1594/PANGAEA.801634