We have published in collaboration with Alice Vho and Daniela Rubatto from the group Metamorphic Geochemistry and with colleagues in Canada and in Italy a paper in Contributions to Mineralogy and Petrology presenting a comprehensive study of element zoning patterns and oxygen isotopes in garnet from the Sesia Zone (Western Alps) in an attempt to decipher the processes linked to crustal reworking associated to fluid flow in the crust. In the studied samples, garnet shows a variety of textures which formed by dissolution–precipitation in presence of fluids.

Garnet major element composition of a selection of eclogite samples from the Sesia Zone (images from Vho et al. 2020). Gray spots show the location of δ18O spot analyses obtained by SIMS.

Garnet in the Sesia Zone documents a shift in δ18O that is attributed to a possible combination of (1) interaction with sea-water derived fluids during pre-Alpine crustal extension and (2) fluids from dehydration reactions occurring during subduction of previously hydrated rocks.

Sketch showing the reconstruction of the paleo-Adriatic margin (a) during rifting and (b) in the pre-subduction geometry (image from Vho et al. 2020).

Find out more

Vho, A., Rubatto, D., Lanari, P., Giuntoli, F., Regis, D., & Hermann, J. (2020). Crustal reworking and hydration: Insights from element zoning and oxygen isotopes of garnet in high-pressure rocks (Sesia Zone, Western Alps, Italy). Contributions to Mineralogy and Petrology, 175, 109. Download pdf | Visit the journal webpage

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