Petrogenesis and Tectonic Implications of the Latest Cretaceous Intrusive Rocks from the Eastern Gangdese Belt, Southeast Tibet

• Published in: Acta geologica Sinica (Beijing) Vol. 96; no. 3; pp. 891 - 903
• Main Authors: CHEN, Yanfei, CHEN, Xuanhua, ZHANG, Zeming, SHAO, Zhaogang, TIAN, Zuolin, DONG, Xin, QIN, Shengkai, YUAN, Yuelei
• Format: Journal Article
• Language: English
• Published: Richmond Wiley Subscription Services, Inc 01.06.2022; Chinese Academy of Geological Sciences,Beijing 100037,China%Chinese Academy of Geological Sciences,Beijing 100037,China; School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China%Institute of Geographic Sciences and Natural Resources Research,Chinese Academy of Sciences,Beijing 100101,China
• Edition: English ed.
• Subjects: Batholiths; Belts; Contamination; Cretaceous; Crystallization; Depletion; eastern Gangdese batholith; Geochronology; Isotopes; Juveniles; Lava; Magma; Neo‐Tethyan ocean; Petrogenesis; regional tectonics; Rock; Rocks; slab rollback; Subduction; Subduction (geology); Tectonics; Tibet; Titanium; Tracking; Zircon; eastern Gangdese batholith; regional tectonics; Neo-Tethyan ocean; Tibet; slab rollback
• ISSN: 1000-9515; 1755-6724
• DOI: 10.1111/1755-6724.14796

The latest Cretaceous magmatic activity in the eastern segment of the Lhasa terrane provides important insights for tracking the magma source and geodynamic setting of the eastern Gangdese batholith, eastward of eastern Himalayan Syntaxis. Detailed petrological, geochemical and geochronological studies of the intrusive rocks (monzodiorites and granodiorites) of the eastern Gangdese batholith are presented with monzodiorites and granodiorites giving zircon U–Pb crystallization dates of 70–66 Ma and 71–66 Ma with εHf(t) values of –4.8 to +6.2 and –1.9 to +5.3, respectively. These rocks are metaluminous to weakly peraluminous I‐type granites showing geochemically arc‐related features of enrichment in LREEs and some LILEs, e.g., Rb, Th, and U, and depletion in HREEs and some HFSEs, e.g., Nb, Ta, and Ti. The rocks are interpreted to be derived from partial melting of mantle material and juvenile crust, respectively, which are proposed to be triggered by Neo‐Tethyan slab rollback during northward subduction, with both experiencing ancient crustal contamination. The studied intrusive rocks formed in a transitional geodynamic setting caused by Neo‐Tethyan oceanic flat subduction to slab rollback beneath the eastern Gangdese belt during the latest Cretaceous.