Possibility of Identification of Back-Arc Paleobasins from High-Grade Orthometamorphite Rocks: Evidence from Basic Crystalline Schists of the Slyudyanka Crystalline Complex, South Baikal Region

摘要

The Slyudyanka crystalline complex is located within the composite Khamar-Daban metamor-phic terrane, the part of the Central Asian fold belt. Geochemical composition of the basic crystalline schists of the Slyudyanka Group (subterrane) metamorphosed under the high-temperature subfacies of the granulite facies suggests that their protoliths were tholeiitic basalts. Their geochemical signatures are intermediate between mid-ocean ridges and island arc basalts, best approximating back-arc basin basalts. The types of the metamorphic rocks of the Slyudyanka Group and their combination in sequences also most correspond to accumulation in back-arc basins. It was concluded that the high-grade metavolcanic rocks retain main geochemical signatures of protoliths, which allows the reconstruction of their paleogeodynamic settings, including back-arc basins.