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The existence of pelitic granulite in the Altai orogen was confirmed for the first time by detailed petrographic research and P-T pseudosection modeling. The pelitic granulite has the assemblage of garnet + cordierite + K-feldspar + biotite + sillimanite + plagioclase + quartz with some samples containing the paragenesis of cordierite + spinel. Peak conditions of the pelitic granulite determined from the P-T pseudosection involved P = 0.5―0.6 GPa, T = 780―800℃, belonging to medium-to low-pressure type. SHRIMP U-Pb dating of zircon presented a metamorphic age of 292.8 ± 2.3 Ma. The discovery of pelitic granulite reflects an extensional environment with high heat flow in the southern margin of the Altai orogen during the Early Permian, which provides an important petrological constraint on the evolution of the Altai orogen.
The existence of pelitic granulite in the Altai orogen was confirmed for the first time by detailed petrographic research and PT pseudosection modeling. The pelitic granulite has the assemblage of garnet + cordierite + K-feldspar + biotite + sillimanite + plagioclase + quartz with some samples containing the paragenesis of cordierite + spinel. Peak conditions of the pelitic granulite determined from the PT pseudosection involved P = 0.5-0.6 GPa, T = 780-800 ° C, belonging to medium-to-low-pressure type. SHRIMP U-Pb dating of zircon The discovery of pelitic granulite an an extensional environment with high heat flow in the southern margin of the Altai orogen during the Early Permian, which provides an important petrological constraint on the evolution of the Altai orogen.