EGUsphere EGUsphere EGUsphere EGUsphere Copernicus Publications Göttingen, Germany 10.5194/egusphere-2026-3680 PyBacktrack 1.5: A community tool for reconstructing paleobathymetry of drill sites, geohistory and global paleobathymetry Müller R. Dietmar https://orcid.org/0000-0002-3334-5764 1 Cannon John https://orcid.org/0000-0003-4749-5605 1 Williams Simon 2 1 Dutkiewicz Adriana 1 Wright Nicky https://orcid.org/0000-0002-5600-3193 1 EarthByte Group, School of Geosciences, University of Sydney, Sydney, NSW 2006, Australia Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, Australia 04 09 2026 2026 1 30 Copyright: © 2026 R. Dietmar Müller et al. 2026 This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/ This article is available from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-3680/ The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-3680/egusphere-2026-3680.pdf

PyBacktrack is a Python community software package that reconstructs the paleo-water depth (paleobathymetry) of ocean drill sites and industry wells through time by combining a model of tectonic subsidence with sediment decompaction and isostatic correction.  Since the release of pyBacktrack 1.0, the software has undergone substantial development that culminates in pyBacktrack 1.5.  The package now (i) runs on Python 3 and is distributed via the Python Package Index, conda-forge and Docker; (ii) includes a new paleobathymetry gridding module that reconstructs and backtracks all submerged present-day crust through geological time to produce time-dependent paleobathymetry grids; (iii) uses an updated default oceanic age-to-depth model, a globally complete set of rift start/end age grids derived from a deforming plate model, an updated total sediment thickness grid and an updated present-day age grid; (iv) supports both mantle and paleomagnetic reference frames and allows the gridded paleobathymetry to be optionally merged with externally produced paleobathymetry on synthetic, subducted crust; and (v) ships with expanded sea-level model and dynamic topography model libraries.  We illustrate pyBacktrack 1.5 with three applications: (1) paleobathymetry reconstructions since the Early Cretaceous of the North Atlantic and the Southern Ocean; (2) one-dimensional backstripping and geohistory analysis at a long-record industry well on the Australian North West Shelf in three configurations (including or omitting eustatic sea level, and including a joint sea level and dynamic topography correction); and (3) a margin-scale gridded tectonic-subsidence-rate analysis of 109 Australian Northwest Shelf industry wells, quantifying how much of the inferred tectonic subsidence rate is dependent on eustatic and dynamic-topographic corrections in space and time.  Together, these developments make pyBacktrack 1.5 a more accessible, extensible and globally applicable framework for reconstructing paleobathymetry and testing the tectonic, sedimentary, sea-level and dynamic-topographic controls on basin evolution.