Cristin-resultat-ID: 1908719
Sist endret: 3. juni 2021, 12:11
Resultat
Vitenskapelig foredrag
2021

A quick a robust numerical modelling method to study the propagation of tides in palaeo-seas

Bidragsytere:
  • Valentin Zuchuat
  • Elisabeth Steel
  • Ryan P. Mulligan
  • Daniel S. Collins og
  • J.A. Mattias Green

Presentasjon

Navn på arrangementet: 35th IAS International Meeting of Sedimentology
Sted: Online
Dato fra: 21. juni 2021
Dato til: 25. juni 2021

Arrangør:

Arrangørnavn: International Association of Sedimentologists

Om resultatet

Vitenskapelig foredrag
Publiseringsår: 2021

Beskrivelse Beskrivelse

Tittel

A quick a robust numerical modelling method to study the propagation of tides in palaeo-seas

Sammendrag

Tidal dynamics in shoreline-shelf systems are dependent on the physiography (geometry and bathymetry) of a basin and its latitude. Researchers can increase their understanding of sedimentary processes in ancient shallow-marine basins, and incorporate potential variations in tidal dynamics in response to an anthropogenically-driven relative sea level change by studying the impact that changes in physiography have on tides. In order to conduct such an analysis in the epicontinental Upper Jurassic Sundance and Curtis Seas, we developed a workflow that everyone can use to model the propagation of tides in ancient basins, to understand the evolution of tidal dynamics in a basin with respect to change in its physiography, or to test the feasibility of certain geological interpretations. The numerical simulations of tides are run in the open-source Deltares Delft3D software, and one of the primary input that the software requires is palaeobathymetric data. Since these data might not exist for the study of ancient marine systems, we developed a simple Python code that extracts the colour-value of every pixel in a georeferenced image, before attributing it a depth value depending on how light- or dark-colour the pixel was: the lighter-coloured the pixel is, the shallower the attributed depth is (and vice-versa). Various tidal constituents can then be forced into the system, either at the same time, if the control on the different tidal constituents in the system is robust, or individually in order for example to minimise assumptions. Such a workflow can quickly test if and how tides can propagate in any given ancient seas, which allows for the testing of certain geological interpretation of the rock record. Our Python-code allows for the very quick generation of multiple palaeobathymetries, by varying the maximum depth attributed to the darkest-coloured pixel of the image, which can then be used to study by proxy the impact of relative sea-level variations on the propagation of tides in ancient seas. The sensitivity of the models can then be tested by varying different input parameters, such as the initial open-ocean tidal forcing, or the bottom drag coefficient values. Delft3d can notably simulate the tidal amplitude and the flow speed anywhere in the system and at any time, but the distribution of sedimentary facies can be predicted for each of the simulation, using the modelled maximum bed shear stress as a proxy. The map of the predicted distribution of sedimentary facies can then be compared to the real distribution of sedimentary facies in the rock record. The study of the Upper Jurassic Sundance and Curtis Sea using this simple but robust workflow allowed us to identify the primary control that the physiographic configuration had on the propagation of tides in the system. This workflow also allowed quantifying how tidal dynamics would evolve with respect to change in palaeophysiographic configuration, which has highlighted the importance of considers the effects of palaeophysiographic changes related to relative sea-level variations and their associated impact on tidal dynamics, which will certainly help improving and refining models of tide-dominated basins and their evolution.

Bidragsytere

Valentin Zuchuat

  • Tilknyttet:
    Forfatter
    ved Seksjon for geologi og geofysikk ved Universitetet i Oslo

Elisabeth Steel

  • Tilknyttet:
    Forfatter

Ryan P. Mulligan

  • Tilknyttet:
    Forfatter

Daniel S. Collins

  • Tilknyttet:
    Forfatter

J.A. Mattias Green

  • Tilknyttet:
    Forfatter
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