282 Crustal Petrology, Part II

This session explores various igneous and metamorphic processes that have shaped Earth’s crust. We welcome contributions from the micro- to macroscale, from the deep to shallow crust, and from field- to laboratory- to modeling-based.

Wednesday, 22 October 2025
1:30 PM - 5:30 PM
HBGCC, 216AB

Modelling vs. Reality: contact-metamorphosed to regionally-metamorphosed pelit

Paper number: 282-13
Program: Technical Sessions
Time: 4:45 PM – 5:00 PM

Authors

  • David Pattison Presenting Author
    Dept Earth, Energy and Environment, U Calgary, Calgary, AB
  • Jacob Forshaw
    Mineral Deposit Research Unit, Department of Earth, Ocean, and Atmospheric Sciences, University of British Columbia, Vancouver, BC

Abstract

Thermodynamically-calculated phase diagrams are predictions, or “models”. They are not reality. They are based on assumed thermodynamic data (end members and solution models), an assumed reactive bulk composition, an assumed chemical system, and assumed attainment of chemical equilibrium of all elements in all phases at all conditions in the phase diagram. Because the aim of modelling is to provide insight about natural processes, a minimum requirement is that it reproduces repeated patterns of natural mineral assemblages and compositions. This presentation assesses how well the most popular thermodynamic models do for metapelites, based on comparison with a worldwide natural database organized by pressure-sensitive mineral assemblage sequences (365 localities; 3,293 samples; 12,429 mineral analyses). Suggestions for future research are made in the light of these results.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-412993

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