Age-Depth Models and Uncertainties for Incompletely Preserved Stratigraphic Sections

Geologic time is incompletely preserved in stratigraphic sections whose sedimentary processes are dominated by erosion or long periods of inactivity. What remains is a fragmentary record that’s punctuated, if we’re lucky, with dateable horizons on which to hang an absolute temporal framework. An important outstanding question is how to map time onto events recorded between the dated horizons. Mass extinctions, isotopic excursions, records of biological evolution, and proxy records of climatic and tectonic processes all generally occur between—not at—dated strata.

To interpolate between dated horizons, geochronologists often create stratigraphic age-depth models. These models create many valid realizations of age–depth relationships that, for instance, obey simple superposition constraints or implement assumptions about average depositional rates and their variability. In parallel, a separate line of sedimentological research has focused on measuring the completeness of stratigraphic records, for instance as a function of the length of the record and its geologic context. The results are one-dimensional mathematical models for sedimentation, erosion, and preservation that capture experimental and observed sedimentary processes in natural systems.

Our presentation aims to connect the efforts of geochronological age-depth modelers with a growing sedimentology literature that models surface evolution using physically parameterized and scaled stochastic processes. We explore methods to create 1D synthetic stratigraphic models conditioned on observed ages with uncertainties, depths, and preserved dated horizons. We then compare our results with currently used age-depth models, focusing on uncertainties in interpolated ages and durations.