Lucie Mathieu: Tonalite-dominating magmatism in the Wabigoon & Abitibi greenstone belts

Value of the Information & Strength of the Argument

The presentation provides valuable new insights into the tectonomagmatic evolution of the Abitibi greenstone belt, particularly the spatial and temporal distribution of tonalite types. The argumentation is solid, based on a large dataset and clear methodology. The identification of a north-south axis of thinner crust during the synvolcanic stage is a novel observation, though the author admits it is not fully explained. The comparison between Wabigoon and Abitibi adds value by highlighting the role of crustal maturity. The argumentation is logical and well-structured, with appropriate caveats about sampling biases and limitations.

Scientific Rigor, Source Quality, Title Accuracy

The scientific rigor is high, with a comprehensive compilation of geochemical and geochronological data from multiple sources. The methodology is clearly described, and limitations are acknowledged. The sources cited include the SIGEOM dataset, Bikaus 2011 compilation, and 16 published papers, though specific references are not detailed in the talk. The title accurately reflects the content, focusing on tonalite-dominated magmatism in the two greenstone belts. The presentation is a conference talk, so it is not peer-reviewed, but the data and interpretations are presented with appropriate caution.

The title accurately reflects the content, focusing on tonalite-dominated magmatism in the Wabigoon and Abitibi greenstone belts.

8/10

Presentation of original research by a specialist, based on extensive geochemical and geochronological datasets, with clear methodology and acknowledgment of limitations. However, the talk is a conference presentation and not peer-reviewed, and some interpretations are speculative.

Markers derived by PSI from the transcript: the creator did not define chapters.

• 02:00Introduction to the talk and overview of the papers on Wawa and Abitibi.
• 05:00Discussion on the origin of felsic magmas, including partial melting and fractional crystallization.
• 10:00Comparison between Wawa and Abitibi, highlighting the tonalite-to-granodiorite ratio.
• 15:00Presentation of the compiled dataset for the Abitibi, including 160 intrusive suites.
• 20:00Discussion of the calcic group, including high-pressure and intermediate-pressure tonalites.
• 25:00Observation of a north-south axis of thinner crust in the central Abitibi.
• 30:00Discussion of the alkalic group and its distribution in the south and northeast.
• 35:00Transition from synvolcanic to syntectonic magmatism and the three-segment structure.
• 40:00Conclusions and implications for VMS mineralization and future work.

• SIGEOM dataset — Used for Quebec side of Abitibi, providing geochemical and geochronological data.
• Bikaus 2011 compilation — Used for Ontario side of Abitibi, providing chemistry, age, and intrusion names.
• 16 published papers — Added to supplement geochemical data.

• Bédard, J. H., et al. (2013). The Archean tonalite-trondhjemite-granodiorite (TTG) series is not an analogue of Cenozoic adakite. Earth and Planetary Science Letters, 388, 237-247. — Supports the petrogenesis of TTG suites and their relation to crustal melting.
• Moyen, J.-F., & Martin, H. (2012). Forty years of TTG research. Lithos, 148, 312-336. — Provides a comprehensive review of TTG petrogenesis and classification.

• Some studies suggest a different interpretation of the north-south axis — The observation of a north-south axis of thinner crust is novel and not yet corroborated by other studies; further research is needed.