Crustal response to continental collisions between the Tibet, Indian, South China and North China Blocks: Geochronological constraints from the Songpan-Garzê Orogenic Belt, western China

Abstract

We report SHRIMP U-Th-Pb monazite, conventional U-Pb titanite, Sm-Nd garnet and Rb-Sr muscovite and biotite ages for metamorphic rocks from the Danba Domal Metamorphic Terrane in the eastern Songpan-Garzê Orogenic Belt (eastern Tibet Plateau). These ages are used to determine the timing of polyphase metamorphic events and the subsequent cooling history. The oldest U-Th-Pb monazite and Sm-Nd garnet ages constrain an early Barrovian metamorphism (M1) in the interval c. 204-190 Ma, coincident with extensive Indosinian granitic magmatism throughout the Songpan- Garzê Orogenic Belt. A second, higher-grade sillimanite-grade metamorphic event (M2), recorded only in the northern part of the Danba te..