Short presentation :

QTQt is a program to infer thermal histories from low temperature thermochronology data using multiple samples. The name comes from QT being Quantitative Thermochronology and Qt (pronounced as “cute” or “cutie”) being the software used to develop the user interface.

The current version allows for multiple sample modelling only if the samples under consideration have the same form of thermal history, i.e. can be treated as a vertical profile (see Gallagher et al. 2005). You can still model a single sample, but for generality we will still refer to a profile (even if there is just one sample). A future version will include the 3D partition model-vertical profile approach developed by Stephenson et al. (2006).

Statistic consideration :

The inversion scheme is Bayesian transdimensional Markov chain Monte Carlo (MCMC), in which the number of time temperature points (or the complexity of the thermal history solutions are inferred from the data rather than being specified in advance). The development of the method for thermal history modelling is given in Gallagher (2012), and some other relevant publications are Gallagher et al. (2009), Charvin et al. (2009), Hopcroft et al. (2007) and Sambridge et al (2006).

The approach as implemented in QTQt allows the user to specify one general time-temperature box, from which time-temperature points are sampled to construct a continuous thermal history by linear interpolation between the sampled points. It also allows for up to 5 additional time-temperature boxes to be specified to allow the user to add more specific constraints on the thermal history.

Technical consideration :

QTQt was written in C and C++ by Kerry Gallagher, although some of the implementation of the fission track annealing algorithms is based substantially on subroutines provided by Richard Ketcham, and Rich’s co-operation is gratefully acknowledged. The zircon radiation damage models are based on codes written by Willy Guenthner, and the Willett apatite radiation damage model is based on code written by Chelsea Willetts…thanks to them for providing their codes. Also, the main routine used for calculating ⁴⁰Ar/³⁹Ar spectra was adapted from code provided by Peter Zeitler (who adapted code originally written by Oscar Lovera), so they are thanked also.

We also acknowledge Qt for providing such a professional programming environment for free. This software would not exist without them.

MacOS and Windows :

QTQt v5.8.5 has been built with Qt 5.12.3 and Qwt 6.1.2.

It was complied with Clang x86 64bit on a Macintosh using OS X 10.14 (Mojave). The current version is 64 bit only and will run on machines with OS X 10.9 (Mavericks) or higher.

The current PC version was compiled with MinGW on Windows 10 and is also 64bit only (although it may be possible to produce a 32bit version if required). It has been tested on various operating systems (Windows 7, XP, Vista), but not extensively.

Contact :

If you have problems with any version (i.e. it crashes), or suggestions for modifications, then feel free to contact Kerry Gallagher.

For a crash, try to give as much detail as you can concerning what you did and how it crashed. Also, send the data files you were using, as that seems to be the most common fault. Some platform specific issues are highlighted in this documentation as PC USERS.. or MAC USERS…

However, read the documentation closely before trying to run the software on your own data – if it is not clear, please contact Kerry Gallagher, who is happy to change things to make them clearer.