Skip to Main content Skip to Navigation
Journal articles

Multistage garnet in high-pressure metasediments: Alpine overgrowths on Variscan detrital grains

Paola Manzotti 1 Michel Ballevre 1
1 Terre, Temps, Traçage
GR - Géosciences Rennes
Abstract : Garnet is commonly found in metamorphic and magmatic rocks, where its growth records the pressure-temperature history of the rock. Petrologists pay particular attention to multistage garnets, because they document the superposition of successive metamorphic stages and/or cycles in orogenic belts. Due to its considerable resistance to mechanical and chemical weathering, garnet is also commonly present as detrital grains in modern and ancient sediments. Therefore, some multistage garnets could potentially result from overgrowths on detrital grains. We report the first discovery of this type of metamorphic overgrowth on detrital garnet grains in a high-pressure metasediment (Money Unit, western Alps). The studied garnet crystals are found in metamorphic rocks derived from matrix-supported conglomerates. Garnet cores display morphological characteristics of the detrital grains and testify that crystals have been corroded as a consequence of abrasion and dissolution. Furthermore, they display a range of compositions incompatible with their growth in a single rock type, implying their provenance from diverse sources. Garnet overgrowths developed on detrital grains during a blueschist facies event, as indicated by chloritoid and rutile inclusions.
Document type :
Journal articles
Complete list of metadatas

https://hal-insu.archives-ouvertes.fr/insu-00907650
Contributor : Isabelle Dubigeon <>
Submitted on : Thursday, November 21, 2013 - 3:24:14 PM
Last modification on : Friday, April 5, 2019 - 8:22:40 PM

Identifiers

Collections

Citation

Paola Manzotti, Michel Ballevre. Multistage garnet in high-pressure metasediments: Alpine overgrowths on Variscan detrital grains. Geology, Geological Society of America, 2013, 41 (11), pp.1151-1154. ⟨10.1130/G34741.1⟩. ⟨insu-00907650⟩

Share

Metrics

Record views

131