Tc1D: a fast and flexible 1-D thermal and thermochronology modeling package for complex exhumation, burial, and transient thermal histories

Thermochronological data can provide robust constraints on crustal exhumation, erosion, and burial, yet their interpretation often requires forward and/or inverse models to account for thermal evolution and the effects of surface processes. Here we present recent developments in T_c1D, a one-dimensional thermal and thermochronometer age prediction package designed to explore exhumation, burial, and other thermal processes and their effects on low-temperature thermochronometers.

T_c1D generates thermal histories by solving the transient one-dimensional heat transfer equation to predict apatite and zircon (U-Th)/He and fission-track ages using established thermochronological models, including RDAAM and ZRDAAM. The thermal model is controlled by user-defined thermal boundary conditions and prescribed vertical crustal dynamics, including erosion and burial. These histories can be parameterized through multiple erosion model options (e.g., stepwise or linearly varying rates) as well as simplified 1-D representations of tectonically driven vertical motions (e.g., thrust-sheet emplacement/removal and extensional/thrust faulting). This physics-based yet computationally efficient setup enables rapid exploration of how various thermal and crustal scenarios translate into predicted age patterns.

T_c1D adopts a complementary approach, compared to commonly used thermal history modeling tools such as HeFTy, QTQt, or Thermochron.jl, enabling direct connection between different vertical-motion scenarios, measured ages, and physical parameters (e.g., erosion rates or eroded thicknesses), while retaining fast execution times suitable for large sensitivity and ensemble analyses. Furthermore, by remaining one-dimensional, T_c1D avoids the computational cost of full 3D thermo-kinematic models such as PECUBE, while still capturing the first-order effects of vertical lithospheric processes. T_c1D is also fully open source and Python based, facilitating transparency, extensibility, and integration into reproducible research workflows.

Recent developments in T_c1D (from version 0.3) expand its scope beyond earlier releases, which were primarily limited to forward modeling and simple erosion scenarios. Recent versions introduce support for data-driven inverse modeling, flexible definitions of exhumation and burial histories, and the inclusion of additional thermal perturbations such as magmatic intrusions. T_c1D now supports parameter inversion using either the Neighborhood Algorithmor a Markov Chain Monte Carloapproach, enabling systematic exploration of exhumation and burial histories. These histories can be defined through an external input file, allowing complex, multi-stage scenarios combining piecewise constant, linear, or exponential phases of erosion/burial.

Ongoing developments focus on improving usability and physical realism. A new unified YAML-based input file is currently being developed to provide an alternative to command-line–driven usage, improving reproducibility while simplifying model design. This structure facilitates the definition and modification of complex model configurations, including multi-stage erosion and burial histories, thermal boundary conditions, and is designed to support future inversion of stage durations and erosion parameters. In parallel, software developments aim to incorporate more realistic representations of crustal structure and rock properties, including depth-dependent density variations based on mineral phase transitions, to better account for crustal composition, thermal properties, and their influence on thermal evolution and erodibility.

These developments are being applied to investigate the long-term thermal evolution of the crust in the Fennoscandian Shield, where low relief, limited sedimentary archives, episodic burial, and subtle post-orogenic exhumation pose major challenges for thermochronological data interpretation.