PyBacktrack 1.4.0

PyBacktrack 1.4 adds support for generating paleobathymetry grids from submerged present-day crust.

Changes since version 1.3:

• Can now generate paleobathymetry grids:
  • Submerged oceanic and continental present-day crust is backtracked and reconstructed.
    • Similar to drill sites, but 2D instead of 1D.
  • Continental subsidence model obtains rifting period from builtin rift grids:
    • In contrast to drill sites where rifting period is explicitly specified.
    • Builtin rift grids:
      • Cover all submerged continental crust, and
      • are generated from Müller 2019 deforming plate model:
        • "A global plate model including lithospheric deformation along major rifts and orogens since the Triassic"
  • All submerged crust is assigned a single lithology, whereas drill sites have multiple stratigraphic layers.
  • Water depths are negative (below sea level) in paleobathymetry grids, but positive in backtracked drill site output.
  • Supports multiple CPUs to reduce running time.
• Supplementary scripts can be installed:
  • Previously was misc/ folder in Github repository, but is now installable.
  • Added script to preferentially merge paleobathymetry grids produced by pybacktrack with externally produced paleobathymetry grids (after adding dynamic topography to external grids).
  • Added script to generate rift start/end time grids from a global deforming model (used to generate builtin rift grids).
  • Added script to extract present day trenches from a global deforming model (used internally to avoid deep bathymetry near trenches).
  • Added script to convert sediment thickness into water thickness based on porosity assuming a single “average ocean floor sediment” lithology.
• Backtracking:
  • Updated builtin total sediment thickness grid to 2019 version:
    • "GlobSed: Updated total sediment thickness in the world's oceans"
  • Updated builtin age grid to 2020 version:
    • "A global dataset of present-day oceanic crustal age and seafloor spreading paramters"
  • Added RHCW18 age-to-depth model:
    • "Structure and dynamics of the oceanic lithosphere-asthenosphere system"
    • Is now the default model (previously was GDH1).
  • Added Cao2019 dynamic topography models (AY18 and KM16):
    • "The interplay of dynamic topography and eustasy on continental flooding in the late Paleozoic"
  • Rift start/end times are no longer required for drill sites on continental crust.
    • Now obtained implicitly from builtin rift grids, if not specified explicitly in drill site file.
• Updated example notebooks:
  • Added notebook to demonstrate paleobathymetry gridding.
  • Added geohistory analysis examples demonstrating backtracking of ocean and shallow continental drill sites.
• Updated functions and classes (API reference):
  • New paleobathymetry functions to:
    • Generate paleobathymetry by reconstructing and backtracking sediment-covered crust through time,
    • write reconstructed paleobathymetry as NetCDF grids.
  • Can decompact at any age (not just ages at stratigraphic boundaries).
    • Assumes a constant sediment deposition rate within each stratigraphic layer.
  • Dynamic topography:
    • Now supports multiple point locations:
      • Previously supported just a single drill site location.
    • Slight change in how grids are interpolated (see notes under DynamicTopography.sample).
      • Note: there is only a difference when interpolating between grid times (no difference at grid times).
    • New class InterpolateDynamicTopography:
      • For just interpolating time-dependent dynamic topography mantle frame grids.
        • Used in above-mentioned script for merging paleobathymetry grids.
      • Existing class DynamicTopography both reconstructs and interpolates.

PyBacktrack 1.3.0

Changes since version 1.2:

• Supports Python 3:
  • please also use the recent pyGPlates Python 3 release.
• Added the following output columns:
  • dynamic_topography:
    • change in dynamic topography elevation since present day
  • decompacted_depth:
    • depth from fully decompacted layers (using surface porosity only)
    • as if no portion of any layer had ever been buried
  • decompacted_sediment_rate:
    • fully decompacted surface layer thickness divided by its deposition interval
• Option to force continental subsidence model:
  • if well site is in age grid (oceanic crust) but known to be on continental crust.
• Option to ignore total sediment thickness grid:
  • if well site is known to be drilled to basement.
• Fixed missing last row of output:
  • when well depth exceeds total sediment thickness.
• Fixed bug in syn-rift subsidence equation:
  • affected tectonic subsidence by less than 1%.

PyBacktrack 1.2.0

Changes since version 1.1:

• Added example notebooks:
  • Backstripped subsidence
  • Visualizing decompaction of stratigraphic layers
• Fixed backstripping example:
  • Original sunrise well depths in metres (not feet).
  • Hence no longer a base sediment layer.
• Added script to convert original sunrise well format to pyBacktrack format.
• Updated functions and classes (API reference):
  • Dynamic topography:
    • Can now access built-in dynamic topography data
      • Previously only available internally in backtracking subsidence model.
      • Access independently of whether you’re backtracking or backstripping.
    • Sampling dynamic topography grids made easier
  • Sea level:
    • Can now access built-in sea level data
    • Fixed bug when age of a stratigraphic layer in well is older than sea-level model.
  • Lithologies:
    • Added function to read and merge multiple lithology definition files
  • Stratigraphic layers:
    • Added tectonic subsidence function
      • Backtracking: returns tectonic subsidence model.
      • Backstripping: returns backstripped subsidence.
    • Added paleo-water depth function
      • Backtracking: returns backtracked water depth.
      • Backstripping: returns average recorded water depth.
    • Added sea-level function
      • Returns sea-level of model specified to backtracking or backstripping.
    • Added dynamic topography function
      • Backtracking: returns dynamic topography relative to present day.
      • Backstripping: returns zero.
  • See usage in example notebooks.

PyBacktrack 1.1.0

Changes since version 1.0.0:

• The example data is now included in the Python package.
  • So you can install it without needing to download from Github.
  • Includes notebooks (such as plotting paleo-water depths for various dynamic topography models).
• Added Docker image.
• Added new inbuilt dynamic topography models ngrand, s20rts and smean (from Müller et al., 2008).
• Can specify more than one lithology definition file.
• Added inbuilt extended lithologies for shallow water (to complement primary lithologies in pyBacktrack 1.0 paper).
• Added “sunrise” backstripping example (uses extended lithologies).
• Can now specify your own oceanic age-to-depth model (instead of just the inbuilt models).
• Fixed bug specifying your own dynamic topography model (inbuilt models were fine though).

PyBacktrack 1.0.0

PyBacktrack is a tool for reconstructing paleobathymetry on oceanic and continental crust.

PyBacktrack is a Python package that backtracks the paleo-water depth of ocean drill sites through time by combining a model of tectonic subsidence with decompaction of the site stratigraphic lithologies. PyBacktrack can also include the effects of mantle-convection driven dynamic topography on paleo-water depth, as well as sea-level variations. PyBacktrack provides a model of tectonic subsidence on both oceanic and continental crust. Ocean crust subsidence is based on a user-selected lithospheric age-depth model and the present-day unloaded basement depth. Continental crust subsidence is based on syn-rift and post-rift subsidence that is modelled using the total sediment thickness at the site and the timing of the transition from rifting to thermal subsidence. On sites that did not penetrate to basement, the age-coded stratigraphy is supplemented with a synthetic stratigraphic section that represents the undrilled section, whose thickness is estimated using a global sediment thickness map. This is essential for estimating the decompacted thickness of the total sedimentary section, and thus bathymetry, through time.