Sarti, Massimo; Kälin, Otto (1992): Stable isotope composition of carbonate components of Rhaetian shallow-water limestones of the Wombat Plateau [dataset]. PANGAEA, https://doi.org/10.1594/PANGAEA.759944, Supplement to: Sarti, M; Kälin, O (1992): Data report: Stable carbon and oxygen isotopic composition of Rhaetian shelf carbonates, Wombat Plateau, Northwest Australia. In: von Rad, U; Haq, BU; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 122, 839-849, https://doi.org/10.2973/odp.proc.sr.122.147.1992
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Abstract:
Stable oxygen- and carbon-isotope ratios of Rhaetian (upper Triassic) limestone samples from the Wombat Plateau, northwest Australia, were measured to explore possible diagenetic pathways that the material underwent after deposition in a shallow-water environment, before plateau submergence in the Early Cretaceous. Host sediment isotopic values cluster near typical marine carbonate values (d18O ranging from -2.57 per mil to +1.78 per mil and d13C, from +2.45 per mil to +4.01 per mil). Isotopic values of equant clear calcite lining or filling rock pores also plot in the
field of marine cements (d18O = +1.59 per mil to -2.24 per mil and d13C = +4.25 per mil to +2.57 per mil), while isotopic values for neomorphic calcites replacing skeletal (megalodontid shell) carbonate material show a wider scatter of oxygen and carbon values, d18O ranging from +2.73 per milo to -6.2 per mil and d13C, from +5.04 per mil to +1.22 per mil.
Selective dissolution of metastable carbonate phases (aragonite?) and neomorphic replacement of skeletal material probably occurred in a meteoric phreatic environment, although replacement products (inclusion-rich microspar, clear neomorphic spar, etc.) retained the original marine isotopic signature because transformation probably occurred in a closed system dominated by the composition of the dissolving phases (high rock/water ratio). The precipitation of late-stage equant (low-Mg?) calcite cement in the pores occurred in the presence of normal marine waters, probably in a deep-water environment, after plateau drowning.
Covariance of d18O and d13C toward negative values indeed suggests influence of meteorically modified fluids. However, none of the samples shows negative carbon values, excluding the persistence of organic-rich soils on subaerial karstic surfaces (Caribbean-style diagenesis). Petrographical and geochemical data are consistent with the sedimentological evidence of plateau drowning in post-Rhaetian times and with a submarine origin of the >70-m.y.-long Jurassic hiatus.
Project(s):
Ocean Drilling Program (ODP)
Coverage:
Median Latitude: -16.680000 * Median Longitude: 115.509067 * South-bound Latitude: -16.737000 * West-bound Longitude: 115.457200 * North-bound Latitude: -16.566000 * East-bound Longitude: 115.535000
Date/Time Start: 1988-07-19T10:00:00 * Date/Time End: 1988-08-22T19:45:00
Minimum Elevation: -2710.0 m * Maximum Elevation: -2179.0 m
Event(s):
122-761B * Latitude: -16.737000 * Longitude: 115.535000 * Date/Time Start: 1988-07-19T10:00:00 * Date/Time End: 1988-07-21T09:00:00 * Elevation: -2179.0 m * Penetration: 286.7 m * Recovery: 199.08 m * Location: South Indian Ridge, South Indian Ocean * Campaign: Leg122 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 33 cores; 286.7 m cored; 0 m drilled; 69.4 % recovery
122-761C * Latitude: -16.737000 * Longitude: 115.535000 * Date/Time Start: 1988-07-21T09:00:00 * Date/Time End: 1988-07-25T02:00:00 * Elevation: -2179.0 m * Penetration: 436.7 m * Recovery: 72.24 m * Location: South Indian Ridge, South Indian Ocean * Campaign: Leg122 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 33 cores; 436.7 m cored; 0 m drilled; 16.5 % recovery
122-764B * Latitude: -16.566000 * Longitude: 115.457200 * Date/Time Start: 1988-08-19T09:45:00 * Date/Time End: 1988-08-22T19:45:00 * Elevation: -2710.0 m * Penetration: 294.5 m * Recovery: 44.33 m * Location: South Indian Ridge, South Indian Ocean * Campaign: Leg122 * Basis: Joides Resolution * Method/Device: Drilling/drill rig (DRILL) * Comment: 31 core; 294.5 m cored; 0 m drilled; 15.1 % recovery
Parameter(s):
| # | Name | Short Name | Unit | Principal Investigator | Method/Device | Comment |
|---|---|---|---|---|---|---|
| 1 | Event label | Event | ||||
| 2 | Sample code/label | Sample label | Sarti, Massimo | DSDP/ODP/IODP sample designation | ||
| 3 | δ13C, carbonate | δ13C carb | ‰ PDB | Sarti, Massimo | Mass spectrometer VG Prism Series II | |
| 4 | δ18O, carbonate | δ18O carb | ‰ PDB | Sarti, Massimo | Mass spectrometer VG Prism Series II | |
| 5 | Lithology/composition/facies | Lithology | Sarti, Massimo | Visual description |
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
Size:
140 data points