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).

ThinSectionThursday

Some crystal “flowers” for #ThinSectionThursday. What mineral(s) could this be?

Yes, these are PPL images of garnet. The crystals shown are texturally sector-zoned (from the incredible collection of Hugh Rice).

JMG Early Career Research Paper Prize to former team member Dr. Freya George

Congratulations to former team member Dr. Freya George for the Mike Brown Annual Early Career JMG Research Paper Prize for the publication: George, F.R. & Gaidies, F. 2020. Simultaneous operation of opposing reaction mechanisms: The influence of matrix heterogeneity on post‐kinematic garnet crystallization in an inverted metamorphic sequence.

According to the Journal of Metamorphic Geology, “The research presents a comprehensive set of observations, acquired through a state‐of‐the‐art multidisciplinary approach, on the 3D microstructural features, chemistry and compositional zoning of garnets in metapelites from an inverted Barrovian sequence in the Sikkim Himalaya. The excellent petrological characterization and careful observations, complemented by nice and self‐explaining figures, are set in the context of other minerals, bulk rock composition and texture. The results are used to model the process of garnet growth at an extreme level of detail, allowing the discussion of the potential tectonic significance of post‐kinematic porphyroblasts in strongly segregated matrices.”

Dr. George is currently a research fellow at Johns Hopkins University (Baltimore, USA).

PhD position in metamorphic petrology and processes

Title Conditions, timing, and mechanisms of metamorphic microstructure development during the Grenvillian orogeny (SE Ontario, Canada)

Description Understanding the origin of rock microstructure is of fundamental importance for refining models of the geodynamic behavior of our planet. The goal of this research is to unravel the conditions, timing and mechanisms of metamorphic microstructure development experienced by rocks of the Grenville Province in SE Ontario (Canada). The roots of this ancient mountain belt are remarkably well preserved in the study area and provide insight into fundamental rock-forming as well as large-scale geodynamic processes that operated during the Proterozoic. Particular focus will be on the better understanding of metamorphic rock microstructure development using a combination of modern petrographic, geochemical, and crystallographic techniques (e.g., XR-µCT, LA-ICP-MS, EBSD), and metamorphic reaction modelling.

A comprehensive petrographic (rock samples and thin sections), geochemical (whole-rock and mineral chemical, isotopic compositions), and microstructural (XR-µCT and EBSD) dataset is already present and can be used by the student during the first year to overcome potential research barriers caused by the Covid-19 pandemic.

Qualifications Highly motivated candidates with a MSc or equivalent degree in the Earth Sciences are encouraged to apply. Preference will be given to a student with a strong background in petrology and geochemistry and the ability to integrate field and laboratory analyses. Experience in the use of analytical instrumentation, such as EPMA, XRF, XRD, as well as a keen interest in the quantitative modelling of metamorphic processes will be an asset.

Benefits This research is funded by a research assistantship and a teaching assistantship for up to five years, starting in May 2021. This position is open until filled.

Application The application deadline is March 1, 2021. Please send your application, including a current CV, a statement of research experience and interests, as well as the contact details of two referees to fred.gaidies@carleton.ca. International students for whom English is not their first language are also required to submit their official Language Proficiency (ESL) test scores (TOEFL/IELTS).

For additional information, please contact Dr. Fred Gaidies here.