Alkaline granitic magmatism of the Western Transbaikalia: Petrogenetic and geodynamic implications from U-Pb isotopic–geochronological data

The Mongolian–Transbaikalian volcanoplutonic belt extends for almost 2000 km through northern Mongolia and Transbaikalia and hosts several hundreds of plutons of alkali feldspar syenites (AFS) and peralkaline granites (PA) that formed at 280–270 and 230–210 Ma. The giant (~220 km2 in area) Sherbakhta pluton in the Vitim plateau (western Transbaikalia) is located and composed of metaluminous (A/CNK ≤1), high ferroan AFS syenites (10.7–12.3 wt% Na2O + K2O; NK/A