2003/01/29 by M.-H. HUANG, M. Huang, I. S. BUICK +1 · 5 citations
Earth and Planetary Sciences · #Geological and Geochemical Analysis #earthquake and tectonic studies #High-pressure geophysics and materials
paper · doi:10.1093/petrology/44.2.255
Abstract The Songpan–Garzê Orogenic Belt (northeastern Tibet Plateau) experienced polyphase deformation and metamorphism that is best developed in the Danba Domal Metamorphic Terrane (DDMT), in which three tectonometamorphic events can be identified. The first event (D1–M1) is characterized by prograde sericite- to kyanite-grade Barrovian metamorphism during late Indosinian (∼205–190 Ma) crustal thickening and shortening. A subsequent early Yanshanian (∼165 Ma) sillimanite- to migmatite-grade event (M2) developed during predominantly east–west compression (D2). A final greenschist-facies event (M3) is best developed in shear zones of probable Himalayan age. P–T conditions during M1 varied from ∼3–5 kbar and ∼410–530°C (biotite zone) to 5·3–8 kbar and 570–600°C (staurolite and kyanite zones), and during M2 from 4·8–6·3 kbar and 640–680°C (sillimanite zone) to 5·8–6·2 kbar and 660–725°C (migmatite zone). Clockwise P–T–t segments were inferred for the staurolite, kyanite and sillimanite zones. Muscovite-dehydration melting duringM2 was largely responsible for the generation of migmatites and locally voluminous pegmatites. The polyphase tectonometamorphic evolution of the eastern Tibet Plateau, as documented in the Danba area, resulted from interactions between the Indian, Tibet, and the South and North China Blocks. The eastern Tibet Plateau experienced limited uplift during the Mesozoic, followed by large-scale uplift and rapid cooling during the Tertiary Himalayan Orogeny.