Downloaded from http://sp.lyellcollection.org/ by guest on October 24, 2018 Gangdese magmatism in southern Tibet and India–Asia convergence since 120 Ma DI-CHENG ZHU1,2*, QING WANG1, SUN-LIN CHUNG3,4, PETER A. CAWOOD5,6 & ZHI-DAN ZHAO1 1State Key Laboratory of Geological Processes and Mineral Resources, and Institute of Earth Sciences, China University of Geosciences, Beijing 100083, China 2CAS Centre for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China 3Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan 4Department of Geosciences, National Taiwan University, Taipei, Taiwan 5School of Earth, Atmosphere and Environment, Monash University, Melbourne, VIC 3800, Australia 6Department of Earth Sciences, University of St Andrews, North Street, St Andrews KY16 9AL, UK *Correspondence:
[email protected] Abstract: A compilation of 290 zircon U–Pb ages of intrusive rocks indicates that the Gangdese Batholith in southern Tibet was emplaced from c. 210 Ma to c. 10 Ma. Two intense magmatic pulses within the batholith occur at: (1) 90 ± 5 Ma, which is restricted to 89–94° E in the eastern segment of the southern Lhasa subterrane; and (2) 50 ± 3 Ma, which is widespread across the entire southern Lhasa subterrane. The latter pulse was fol- lowed by a phase of widespread but volumetrically small, dominantly felsic adakitic intrusive rocks at 16 ± 2 Ma. The Linzizong volcanism in the Linzhou Basin was active from 60.2 to 52.3 Ma, rather than 69– 44 Ma as previously estimated. During 120–75 Ma, Gangdese Batholith magmatism migrated from south to north, arguing against rollback of the downgoing, north-dipping Neo-Tethyan oceanic lithosphere for the gen- eration of the 90 ± 5 Ma magmatic pulse.