Spiegel, Cornelia; Kohn, Barry; Belton, David; Berner, Zsolt; Gleadow, Andrew (2009): Geochemistry of Apatite from rapid cooled samples [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.789000, Supplement to: Spiegel, C et al. (2009): Apatite (U–Th–Sm)/He thermochronology of rapidly cooled samples: The effect of He implantation. Earth and Planetary Science Letters, 285(1-2), 105-114, https://doi.org/10.1016/j.epsl.2009.05.045
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Abstract:
Apatite (U-Th-Sm)/He (AHe) thermochronology is increasingly used for reconstructing geodynamic processes of the upper crust and the surface. Results of AHe thermochronology, however, are often in conflict with apatite fission track (AFT) thermochronology, yielding an inverted age-relationship with AHe dates older than AFT dates of the same samples. This effect is mainly explained by radiation damage of apatite, either impeding He diffusion or causing non-thermal annealing of fission tracks. So far, systematic age inversions have only been described for old and slowly cooled terranes, whereas for young and rapidly cooled samples 'too old' AHe dates are usually explained by the presence of undetected U and/or Th-rich micro-inclusions. We report apatite (U-Th-Sm)/He results for rapidly cooled volcanogenic samples deposited in a deep ocean environment with a relatively simple post-depositional thermal history. Robust age constraints are provided independently through sample biostratigraphy. All studied apatites have low U contents (< 5 ppm on average). While AFT dates are largely in agreement with deposition ages, most AHe dates are too old. For leg 43, where deposition age of sampled sediment is 26.5-29.5 Ma, alpha-corrected average AHe dates are up to 45 Ma, indicating overestimations of AHe dates up to 50%. This is explained by He implantation from surrounding host U-Th rich sedimentary components and it is shown that AHe dates can be "corrected" by mechanically abrading the outer part of grains. We recommend that particularly for low U-Th-apatites the possibility of He implantation should be carefully checked before considering the degree to which the alpha-ejection correction should be applied.
Project(s):
Deep Sea Drilling Project (DSDP)
Ocean Drilling Program (ODP)
Coverage:
Median Latitude: 9.353987 * Median Longitude: 25.417653 * South-bound Latitude: -31.030000 * West-bound Longitude: -64.249000 * North-bound Latitude: 31.186800 * East-bound Longitude: 152.322900
Date/Time Start: 1975-07-24T00:00:00 * Date/Time End: 1989-12-05T20:27:00
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
Size:
3 datasets
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Datasets listed in this publication series
- Spiegel, C; Kohn, B; Belton, D et al. (2009): (Table S2) Characteristics of analysed apatite grains from rapidly cooled samples. https://doi.org/10.1594/PANGAEA.788998
- Spiegel, C; Kohn, B; Belton, D et al. (2009): (Table 2) U, Th, and Sm of apatite from rapidly cooled samples. https://doi.org/10.1594/PANGAEA.788995
- Spiegel, C; Kohn, B; Belton, D et al. (2009): (Table 1) U, Th, and Sm of rapidly cooled samples. https://doi.org/10.1594/PANGAEA.788994