The Himalayan Collisional Orogeny: A Metamorphic Perspective

• Published in: Acta geologica Sinica (Beijing) Vol. 96; no. 6; pp. 1842 - 1866
• Main Authors: WANG, Jiamin, WU, Fuyuan, ZHANG, Jinjiang, KHANAL, Gautam, YANG, Lei
• Format: Journal Article
• Language: English
• Published: Richmond Wiley Subscription Services, Inc 01.12.2022; Department of Mines and Geology of Nepal,Kathrnandu 44600,Nepal%State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China; State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China%School of Earth and Space Sciences,Peking University,Beijing 100871,China%State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China; College of Earth Sciences,Chengdu University of Technology,Chengdu 610059,China
• Edition: English ed.
• Subjects: Asthenosphere; Carbon cycle; continental collision; critical taper wedge and channel flow; crustal thickening; Decarbonation; Delamination; Himalaya; Isotopes; Metals; Metamorphism; Mineralization; mountain uplift; Mountains; Ocean circulation; Orogeny; P‐T‐t path; Roots; Topography; Upwelling; P-T-t path; mountain uplift; critical taper wedge and channel flow; crustal thickening; continental collision; Himalaya
• ISSN: 1000-9515; 1755-6724
• DOI: 10.1111/1755-6724.15022

This paper introduces how crustal thickening controls the growth of the Himalaya by summarizing the P‐T‐t evolution of the Himalayan metamorphic core. The Himalayan orogeny was divided into three stages. Stage 60–40 Ma: The Himalayan crust thickened to ∼40 km through Barrovian‐type metamorphism (15–25 °C/km), and the Himalaya rose from <0 to ∼1000 m. Stage 40–16 Ma: The crust gradually thickened to 60–70 km, resulting in abundant high‐grade metamorphism and anatexis (peak‐P, 15–25 °C/km; peak‐T, >30 °C/km). The three sub‐sheets in the Himalayan metamorphic core extruded southward sequentially through imbricate thrusts of the Eo‐Himalayan thrust, High Himalayan thrust, and Main Central thrust, and the Himalaya rose to ≥5,000 m. Stage 16–0 Ma: the mountain roots underwent localized delamination, causing asthenospheric upwelling and overprinting of the lower crust by ultra‐high‐temperature metamorphism (30–50 °C/km), and the Himalaya reached the present elevation of ∼6,000 m. Underplating and imbricate thrusting dominated the Himalaya' growth and topographic rise, conforming to the critical taper wedge model. Localized delamination of mountain roots facilitated further topographic rise. Future Himalayan metamorphic studies should focus on extreme metamorphism and major collisional events, contact metamorphism and rare metal mineralization, metamorphic decarbonation and the carbon cycle in collisional belts.