Metamorphic evolution of high-alumina metapelites near the Panimba overthrust (Yenisei Range: mineral associations, PT-conditions, and tectonic model
Likhanov I. I., Polyanskii O. P., Reverdatto V. V., Kozlov P. S., Vershinin A. E., Krebs M., and Memmi I.
Keywords: High-alumina metapelites, thermobarometry, PT-paths, tectonic model, Yenisei Range
Pages: 1205-1220
Abstract
An attempt is made to study pressure-heterogeneous high-alumina metapelites of andalusite-sillimanite and kyanite-sillimanite facies series for clearing up the PT-evolution of metamorphism related to thrusting tectonics. As a result of detailed research with the use of geothermobarometry and THERMOCALC-based analysis of mineral equilibria, PT-conditions were estimated and PT-paths of evolution were plotted for moderate and elevated pressures. The obtained data on the change of PT-conditions of metamorphism suggest that the kyanite substitution for andalusite and other mineral transformations were caused by an increase in pressure under low geothermal gradient, described by a model for tectonic thickening of the crust in the zone of the Panimba overthrust. The absence of a marked increase in temperature on thrusting is explained by specific behavior of stationary geotherms for different kinds of rocks that have different thermophysical and heat-producing properties.
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