PyCurious

PyCurious estimates the Curie point depth — the depth at which rock loses its magnetisation — from the radially averaged spectrum of a magnetic anomaly.

Magnetic data is one of the most common geophysics datasets available at the surface of the Earth. The most prevalent magnetic mineral is magnetite, whose Curie point is 580 °C, so the Curie depth is often interpreted as the 580 °C isotherm. PyCurious computes the (fast) Fourier transform over square windows of a magnetic anomaly reduced to the pole and estimates the depth and thickness of the magnetic source from the slope of the radial spectrum. It implements two methods, sharing one grid and spectrum layer, and — the defining feature of v2 — both return uncertainties:

• Bouligand et al. (2009) — fits a four-parameter analytic spectrum (beta, zt, dz, C) by optimisation, with a full Bayesian toolkit (profile-deviance intervals, Metropolis–Hastings sampling, sensitivity analysis).

• Tanaka et al. (1999) — the centroid method: two straight lines fitted to separate wavenumber bands, each weighted by the measured spectral scatter.

PyCurious ingests maps of the magnetic anomaly and distributes the computation of Curie depth across multiple CPUs.

Citation

Mather, B. and Delhaye, R. (2019). PyCurious: A Python module for computing the Curie depth from the magnetic anomaly. Journal of Open Source Software, 4(39), 1544, https://doi.org/10.21105/joss.01544

Contents

• Getting started
  • Installation
  • A first spectrum
  • Running the tests
• Software dependencies
  • Core dependencies
  • Optional extras
• Tutorials
  • Bouligand — fitting the fractal spectrum
  • Tanaka — the centroid method
• Theory
  • The Bouligand fractal model
  • The Tanaka centroid method
  • Conventions
• API reference
  • Grid and spectra
  • Bouligand optimiser
  • Tanaka optimiser
  • Synthetic and analytic spectra
  • Mapping
  • Downloads
  • Deprecated
• Contributing to pycurious
  • How to create a Pull Request (PR)
  • When to make your pull request
  • We want your help!
  • Tests
  • Building the documentation
  • Releasing (maintainers)

References

1. Bouligand, C., Glen, J. M. G., & Blakely, R. J. (2009). Mapping Curie temperature depth in the western United States with a fractal model for crustal magnetization. Journal of Geophysical Research, 114(B11104), 1–25. https://doi.org/10.1029/2009JB006494

2. Tanaka, A., Okubo, Y., & Matsubayashi, O. (1999). Curie point depth based on spectrum analysis of the magnetic anomaly data in East and Southeast Asia. Tectonophysics, 306(3–4), 461–470. https://doi.org/10.1016/S0040-1951(99)00072-4