New paper alert!

Another chapter of Zhen’s PhD thesis has just been accepted for publication in Contributions to Mineralogy and Petrology - congratulations!

In this work, Zhen investigated texturally and chemically sector-zoned garnet crystals in rocks from the Danba dome (eastern Tibetan Plateau, SW China), integrating petrographic analyses with XR-µCT, EPMA, LA-ICP-MS, EBSD, and phase equilibrium modelling. The results of this research suggest that abundant graphite likely played a pivotal role in changing fluid conditions and reducing the solubility of SiO2 to grow sector-zoned garnet, as well as impeding matrix coarsening. Development of sector-zoned core and dodecahedral faces of garnet may be related to rapid growth with changes in crystal morphology. Irregular sectors may have developed through fluid infiltration and local chemical adjustments.

Li, Z.M., Gaidies, F., Chen, YC. et al. Petrogenesis of sector-zoned garnet in graphitic metapelite from the Danba dome, eastern Tibetan Plateau (SW China). Contrib Mineral Petrol 179, 56 (2024). https://doi.org/10.1007/s00410-024-02139-8

New MSc project with the Geological Survey of Canada

Are you interested in metamorphic petrology, geochronology, and petrochronology, and would like to combine laboratory analyses with fieldwork?

Then this completely funded MSc project between the Geological Survey of Canada (Drs. Tarryn Cawood and Jamie Cutts) and Carleton University (Dr. Fred Gaidies) may be something for you:

Investigating the Timing and Conditions of Metamorphism near Dryden, Ontario

For French version, please see here.

Closing date for applications is 30 April 2024. For further details or questions, please get in touch.

New paper alert: Mechanisms and durations of metamorphic garnet crystallization in the lower nappes of the Caledonian Kalak Nappe Complex, Arctic Norway

Congratulations to Thereza who just published the first chapter of her PhD thesis!

This paper outlines the results of detailed microstructural and compositional investigations of garnet populations, and how this information can be used to estimate the durations of metamorphic events:

Yogi* MTAG, Gaidies F, Heldwein* OKA, Rice AHN. Mechanisms and durations of metamorphic garnet crystallization in the lower nappes of the Caledonian Kalak Nappe Complex, Arctic Norway. Journal of Metamorphic Geology doi:10.1111/jmg.12766.

Microstructural analysis of a garnet population. See Yogi et al. (2024) for details.

Compositional analysis of a garnet population. Details in Yogi et al. (2024).

Identical metamorphic record in distinct petrochemical systems

Great news before the year ends: Zhen’s new paper just got accepted for publication!

Li, Z.M.G, Chen, Y.-C., Gaidies, F., Zhao, Y.-L., Wu, C.-M. (2023). Identical metamorphic record in distinct petrochemical systems: case study of microscopically interlayered garnet amphibolite and metapelite from the Danba dome, SW China. Lithos. https://doi.org/10.1016/j.lithos.2023.107488

Congratulations Zhen!

Polymetamorphism during the Grenvillian Orogeny in SE Ontario: Results from trace element mapping, in-situ geochronology, and diffusion geospeedometry

Our latest research unlocks the fascinating history of metamorphic rocks from the Grenville Province of SE Ontario. Using a variety of techniques, including high-resolution XR-µCT, LA-ICP-MS, and in-situ Lu-Hf geochronology, we are able to provide evidence for repeated metamorphic events during the Grenvillian Orogeny. Garnet crystals, which formed during these events, developed spectacular compositional and microstructural properties, and, once again, acted as the geological time capsules needed to gain insight into our planet’s past.

Read the preprint here, and the published version here:

Gaidies F, McCarron T, Simpson A, Easton RM, Glorie S, Putlitz B, Trebus K (2023) Polymetamorphism during the Grenvillian Orogeny in SE Ontario: Results from trace element mapping, in-situ geochronology, and diffusion geospeedometry. Journal of Metamorphic Geology, DOI: 10.1111/jmg.12745

Sneak preview of some recent research on elongated garnets with hexagonal symmetry!

Garnet is isometric, forming dodecahedral or trapezohedral crystals? Well, the ones shown in color below have hexagonal symmetry, with their long, three-fold rotation axes aligned at large angles to the rock matrix foliation.

Stay tuned for some recent results, integrating CT scanning, LA-ICP-MS mapping and in-situ Lu-Hf geochronology!

Graduate course in Advanced Metamorphic Petrology

This coming winter, I will offer again my annual Advanced Metamorphic Petrology course. This course is open for graduate students at any Ontario university and will be delivered online (synchronously), so there is no real limit to the number of participating students.

Similar to previous years, this course covers many aspects important for the quantitative analysis of metamorphic mineral reactions, including (i) stoichiometry (compositional space, barycentric projection, stoichiometric equations in closed systems), (ii) equilibrium thermodynamics (equilibrium states, minimum Gibbs energy as criterion for stable equilibrium, equilibrium phase relations, molar free energy diagrams), (iii) introduction to and applications of the Theriak-Domino software (phase diagrams, phase equilibria along PT paths, chemical fractionation, metamorphic fluids, buffers), (iv) chemical diffusion (Fick’s law, continuity equation, analytical and numerical solutions, geospeedometry), (v) classical nucleation theory, (vi) crystal growth theories (porphyroblasts, coronas, symplectites), and (vii) crystal growth simulations using the Theria_G software.

If you are interested in this course and would like to register, or have any questions about it, please get in touch.

150 Myr of Episodic Metamorphism Recorded in the Yukon-Tanana Terrane, Northern Canadian Cordillera

New paper alert!

Soucy La Roche R, Dyer SC, Zagorevski A, Cottle JM, Gaidies F (2022) 150 Myr of Episodic Metamorphism Recorded in the Yukon-Tanana Terrane, Northern Canadian Cordillera: Evidence from Monazite and Xenotime Petrochronology. Lithosphere 2022(1) doi:10.2113/2022/7708357

Lead by Renaud Soucy La Roche @inrsciences, with former MSc student Sabastien Dyer @DireGeologist, Alex Zagorevski @GSC_CGC, and John Cottle @antarctica360.

New THERIA_G version!

The influence of pressure on the energy barrier of multi-component diffusion in garnet when using the Chakraborty and Ganguly (1992) dataset has been slightly underestimated in previous versions of THERIA_G. The updated version (available for MacOS here; PC version will be added soon) rectifies this. Thanks to Hugo Dominguez (PhD student @unibern with @PierreLanari) for pointing this out!

#opensource #Theria_G

Published: "Testing the equilibrium model: An example from the Caledonian Kalak Nappe Complex (Finnmark, Arctic Norway)"

Just in time for Christmas Eve, our latest paper is now typeset and available online here. The accepted preprint can be found here.

Merry Christmas!

Gaidies F, Heldwein OKA, Yogi MTAG, Cutts JA, Smit MA, Rice AHN (2022) Testing the equilibrium model: An example from the Caledonian Kalak Nappe Complex (Finnmark, Arctic Norway). Journal of Metamorphic Geology doi:https://doi.org/10.1111/jmg.12648

New paper alert!

Congratulations to former student Brigid Christison for the publication of her BScH research in Journal of Mammalogy! This research has been co-supervised by Dr. Dani Fraser from the Canadian Museum of Nature.

Christison BE, Gaidies F, Pineda-Munoz S, Evans AR, Gilbert MA, Fraser D (2021) Dietary niches of creodonts and carnivorans of the late Eocene Cypress Hills Formation. Journal of Mammalogy doi:10.1093/jmammal/gyab123