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

摘要: We report SHRIMP U–Th–Pb monazite, conventional U–Pb titanite, Sm–Nd garnet and Rb–Sr muscovite biotite ages for metamorphic rocks from the Danba Domal Metamorphic Terrane in eastern Songpan-Garze Orogenic Belt (eastern Tibet Plateau). These are used to determine timing of polyphase events subsequent cooling history. The oldest monazite constrain an early Barrovian metamorphism (M1) interval c. 204–190 Ma, coincident with extensive Indosinian granitic magmatism throughout Belt. A second, higher-grade sillimanite-grade event (M2), recorded only northern part terrane, was dated at 168–158 Ma by a combination titanite ages. It is suggested that M1 thermal affected entire orogenic belt while M2 may represent local perturbation. range 138–100 Ma, whereas cluster 34–24 Ma. document regional rates 2–3 °C Myr−1 following peak most terrane. However, those parts terrane higher-temperature (e.g. migmatite zone) experienced initially more rapid (c. 8 °C Myr−1) after before joining slow path defined rest 138 Ma. Regional between 138 30 Ma thought be result post-tectonic isostatic uplift crustal thickening caused collision South North China Blocks. clustering marks onset across commencing 30–20 Ma. This history shared many other regions Plateau, suggesting Plateau (including Belt) occurred predominantly last 30 Myr as response continuing northwards India Eurasia.