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An improved approach to age-modeling in deep time: Implications for the Santa Cruz Formation, Argentina

Publication ,  Journal Article
Trayler, RB; Schmitz, MD; Cuitiño, JI; Kohn, MJ; Bargo, MS; Kay, RF; Strömberg, CAE; Vizcaíno, SF
Published in: Bulletin of the Geological Society of America
January 1, 2020

Accurate age-depth models for proxy records are crucial for inferring changes to the environment through space and time, yet traditional methods of constructing these models assume unrealistically small age uncertainties and do not account for many geologic complexities. Here we modify an existing Bayesian age-depth model to foster its application for deep time U-Pb and 40Ar/39Ar geochronology. More flexible input likelihood functions and use of an adaptive proposal algorithm in the Markov Chain Monte Carlo engine better account for the age variability often observed in magmatic crystal populations, whose dispersion can reflect inheritance, crystal residence times and daughter isotope loss. We illustrate this approach by calculating an age-depth model with a contiguous and realistic uncertainty envelope for the Miocene Santa Cruz Formation (early Miocene; Burdigalian), Argentina. The model is calibrated using new, high-precision isotope dilution U-Pb zircon ages for stratigraphically located interbedded tuffs, whose weighted mean ages range from ca. 16.78 ± 0.03 Ma to 17.62 ± 0.03 Ma. We document how the Bayesian age-depth model objectively reallocates probability across the posterior ages of dated horizons, and thus produces better estimates of relative ages among strata and variations in sedimentation rate. We also present a simple method to propagate age-depth model uncertainties onto stratigraphic proxy data using a Monte Carlo technique. This approach allows us to estimate robust uncertainties on isotope composition through time, important for comparisons of terrestrial systems to other proxy records.

Duke Scholars

Published In

Bulletin of the Geological Society of America

DOI

EISSN

1943-2674

ISSN

0016-7606

Publication Date

January 1, 2020

Volume

132

Issue

1-2

Start / End Page

233 / 244

Related Subject Headings

  • Geology
  • 37 Earth sciences
  • 0404 Geophysics
  • 0403 Geology
  • 0402 Geochemistry
 

Citation

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Trayler, R. B., Schmitz, M. D., Cuitiño, J. I., Kohn, M. J., Bargo, M. S., Kay, R. F., … Vizcaíno, S. F. (2020). An improved approach to age-modeling in deep time: Implications for the Santa Cruz Formation, Argentina. Bulletin of the Geological Society of America, 132(1–2), 233–244. https://doi.org/10.1130/B35203.1
Trayler, R. B., M. D. Schmitz, J. I. Cuitiño, M. J. Kohn, M. S. Bargo, R. F. Kay, C. A. E. Strömberg, and S. F. Vizcaíno. “An improved approach to age-modeling in deep time: Implications for the Santa Cruz Formation, Argentina.” Bulletin of the Geological Society of America 132, no. 1–2 (January 1, 2020): 233–44. https://doi.org/10.1130/B35203.1.
Trayler RB, Schmitz MD, Cuitiño JI, Kohn MJ, Bargo MS, Kay RF, et al. An improved approach to age-modeling in deep time: Implications for the Santa Cruz Formation, Argentina. Bulletin of the Geological Society of America. 2020 Jan 1;132(1–2):233–44.
Trayler, R. B., et al. “An improved approach to age-modeling in deep time: Implications for the Santa Cruz Formation, Argentina.” Bulletin of the Geological Society of America, vol. 132, no. 1–2, Jan. 2020, pp. 233–44. Scopus, doi:10.1130/B35203.1.
Trayler RB, Schmitz MD, Cuitiño JI, Kohn MJ, Bargo MS, Kay RF, Strömberg CAE, Vizcaíno SF. An improved approach to age-modeling in deep time: Implications for the Santa Cruz Formation, Argentina. Bulletin of the Geological Society of America. 2020 Jan 1;132(1–2):233–244.

Published In

Bulletin of the Geological Society of America

DOI

EISSN

1943-2674

ISSN

0016-7606

Publication Date

January 1, 2020

Volume

132

Issue

1-2

Start / End Page

233 / 244

Related Subject Headings

  • Geology
  • 37 Earth sciences
  • 0404 Geophysics
  • 0403 Geology
  • 0402 Geochemistry