Preprints
https://doi.org/10.5194/egusphere-2024-2857
https://doi.org/10.5194/egusphere-2024-2857
30 Sep 2024
 | 30 Sep 2024
Status: this preprint is open for discussion.

Nonparametric estimation of age-depth models from sedimentological and stratigraphic information

Niklas Hohmann, David De Vleeschouwer, Sietske Batenburg, and Emilia Jarochowska

Abstract. Age-depth models are fundamental tools used in all geohistorical disciplines. They assign stratigraphic positions to ages (e.g., in drill cores or outcrops), which is necessary to estimate rates of past environmental change and establish timing of events in sedimentary sequences. Methods to estimate age-depth models commonly use simplified parametric assumptions on the uncertainties of ages of tie points. The distribution of time between tie points is estimated using simplistic assumptions on the formation of the stratigraphic record, for example that sediment accumulates in discrete events that follow a Poisson process. In general, age-depth models are a crude simplification that fail to provide a comprehensive implementation of all empirical data or expert knowledge (e.g., from sedimentary structures such as erosional surfaces or from basin models). In other words, many information sources that can potentially provide geochronologic information remain un- or underused.

Here, we present two non-parametric methods to estimate age-depth models from complex sedimentological and stratigraphic data. The methods are complementary as they use different sources of information (sedimentation rates and observed tracer values), are implemented in the admtools package for R Software and allow the user to specify any error model and distribution of uncertainties.

As use cases of the methods, we

  • construct age-depth models for the Late Devonian Steinbruch Schmidt section in Germany and use it to estimate the timing of the Frasnian-Famennian boundary and the duration of the Upper Kellwasser event.
  • use measurements of extra-terrestrial 3He from ODP site 960 (Maud Rise, Weddell Sea) to construct age-depth models for the Paleocene–Eocene thermal maximum (PETM).

The first case study suggests that the Upper Kellwasser event lasted 89 kyr (IQR: 84 to 97 kyr) and places the Frasnian-Famennian boundary at 371.834 ± 0.101 Ma (2 σ), whereas the second case study provides a duration of 41 to 48 kyr for the PETM recovery interval.

These examples show how information from a variety of sedimentological and stratigraphic sources can be combined to estimate age-depth relationships that accurately reflect uncertainties of both available data and expert knowledge.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
Niklas Hohmann, David De Vleeschouwer, Sietske Batenburg, and Emilia Jarochowska

Status: open (until 12 Jan 2025)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-2857', Maarten Blaauw, 25 Oct 2024 reply
  • CC1: 'Problematic', Richard Zeebe, 03 Nov 2024 reply
  • CC2: 'Comment on egusphere-2024-2857', Robin Trayler, 20 Nov 2024 reply
    • AC1: 'Reply on CC2', Niklas Hohmann, 27 Nov 2024 reply
  • CC3: 'Comment on egusphere-2024-2857', Jarno Huygh, 21 Nov 2024 reply
Niklas Hohmann, David De Vleeschouwer, Sietske Batenburg, and Emilia Jarochowska
Niklas Hohmann, David De Vleeschouwer, Sietske Batenburg, and Emilia Jarochowska

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Short summary
Age-depth models assign ages to sampling locations (e.g., in drill cores), making them crucial to determined timing and pace of past changes. We present two methods to estimate age-depth models from sedimentological and stratigraphic information, resulting in richer and more empirically realistic age-depth models. As a use case, we determine (1) the timing of the Frasnian-Famennian extinction and (2) examine the duration of PETM, an potential deep time analogue for anthropogenic climate change.