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Blättler, Clara L; Jenkyns, Hugh C; Reynard, Linda M; Henderson, Gideon M (2011): Calcium isotope composition of Oceanic Anoxic Events 1a and 2 sediments [dataset publication series]. PANGAEA, https://doi.org/10.1594/PANGAEA.786953, Supplement to: Blättler, CL et al. (2011): Significant increases in global weathering during Oceanic Anoxic Events 1a and 2 indicated by calcium isotopes. Earth and Planetary Science Letters, 309(1-2), 77-88, https://doi.org/10.1016/j.epsl.2011.06.029

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Abstract:
Calcium-isotope ratios (d44/42Ca) were measured in carbonate-rich sedimentary sections deposited during Oceanic Anoxic Events 1a (Early Aptian) and 2 (Cenomanian-Turonian). In sections from Resolution Guyot, Mid-Pacific Mountains; Coppitella, Italy; and the English Chalk at Eastbourne and South Ferriby, UK, a negative excursion in d44/42Ca of ~0.20 per mil and ~0.10 per mil is observed for the two events. These d44/42Ca excursions occur at the same stratigraphic level as the carbon-isotope excursions that define the events, but do not correlate with evidence for carbonate dissolution or lithological changes. Diagenetic and temperature effects on the calcium-isotope ratios can be discounted, leaving changes in global seawater composition as the most probable explanation for d44/42Ca changes in four different carbonate sections. An oceanic box model with coupled strontium- and calcium-isotope systems indicates that a global weathering increase is likely to be the dominant driver of transient excursions in calcium-isotope ratios. The model suggests that contributions from hydrothermal activity and carbonate dissolution are too small and short-lived to affect the oceanic calcium reservoir measurably. A modelled increase in weathering flux, on the order of three times the modern flux, combined with increased hydrothermal activity due to formation of the Ontong-Java Plateau (OAE1a) and Caribbean Plateau (OAE2), can produce trends in both calcium and strontium isotopes that match the signals recorded in the carbonate sections. This study presents the first major-element record of a weathering response to Oceanic Anoxic Events.
Project(s):
Ocean Drilling Program (ODP)
Coverage:
Median Latitude: 41.908150 * Median Longitude: 47.578525 * South-bound Latitude: 21.332600 * West-bound Longitude: -0.500000 * North-bound Latitude: 53.700000 * East-bound Longitude: 174.314100
Date/Time Start: 1992-04-07T09:30:00 * Date/Time End: 1992-04-24T07:30:00
License:
Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
Size:
4 datasets

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Datasets listed in this publication series

  1. Blättler, CL; Jenkyns, HC; Reynard, LM et al. (2011): (Table 1) Calcium isotope composition of ODP Hole 143-866A samples. https://doi.org/10.1594/PANGAEA.786949
  2. Blättler, CL; Jenkyns, HC; Reynard, LM et al. (2011): (Table 2) Calcium isotope composition of Cappitella, Gargano samples. https://doi.org/10.1594/PANGAEA.786950
  3. Blättler, CL; Jenkyns, HC; Reynard, LM et al. (2011): (Table 3) Calcium isotope composition of Eastbourne, Sussex samples. https://doi.org/10.1594/PANGAEA.786951
  4. Blättler, CL; Jenkyns, HC; Reynard, LM et al. (2011): (Table 4) Calcium and carbon isotope composition of South Ferriby, Lincolnshire samples. https://doi.org/10.1594/PANGAEA.786952