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- Title
P–T Paths of Cooling and Metamorphism under Conditions of Low-Grade Amphibolite Facies in the Xenoliths of Granulites in the Siberian Craton.
- Authors
Grigorieva, V. M.; Perchuk, A. L.; Shatsky, V. S.; Zinovieva, N. G.
- Abstract
The results of detailed petrological studies of mafic granulites from the Yubileinaya (Alakit-Markha field) and Novinka (Upper–Muna field) kimberlite pipes, where retrograde metamorphic P–T paths were reconstructed for the first time using mineral geothermobarometry, are provided. These P–T paths demonstrate subisobaric transition of the rocks from the P–T conditions of low-grade granulite facies to low-grade amphibolite facies at the depth of the middle crust. It was found that the compositions of garnet, clinopyroxene, and orthopyroxene depend on the adjacent mineral, reflecting the different closure temperatures of the exchange mineral reactions. The higher temperatures are determined using a two-pyroxene geothermometer, while the lower ones are found by application of garnet–clinopyroxene and garnet–orthopyroxene geothermometers. Phase equilibria modeling showed the thermodynamic conditions of the low-grade amphibolite facies: 540°C, 0.76 GPa, lgfO2 = QFM + 1.7 (Yubileinaya pipe); 530°C, 0.72 GPa, lgfO2 = QFM + 2.2 (Novinka pipe). The stability of the granulite paragenesis of garnet + clinopyroxene + orthopyroxene + plagioclase under such P–T conditions is a poorly known phenomenon reflecting a deficit of aqueous fluid during the crystallization of gabbroids and their subsequent cooling in the deep segments of cratons.
- Subjects
GARNET; AMPHIBOLITES; FACIES; INCLUSIONS in igneous rocks; GRANULITE; PHASE equilibrium; PLAGIOCLASE; ORTHOPYROXENE
- Publication
Doklady Earth Sciences, 2024, Vol 514, Issue 1, p84
- ISSN
1028-334X
- Publication type
Article
- DOI
10.1134/S1028334X23602687