Petrogenesis and metallogenic implications of Cretaceous magmatism in Central Lhasa, Tibetan Plateau: A case study from the Lunggar Fe skarn deposit and perspective review

Hua Wen Cao, Yun Hui Zhang*, M. Santosh, Guang Ming Li, Steven P. Hollis, Lin Kui Zhang, Qiu Ming Pei, Li Tang, Zhi Ming Duan

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The Lhasa terrane is one of the major segments of the Tibetan Plateau, with widespread Mesozoic to Cenozoic magmatic and metallogenic records. Here, we investigate timing and characteristics of magmatism associated with the Lunggar Fe skarn deposit in Central Lhasa. We also present Sr–Nd–Pb and Hf (zircon) isotopic data on three associated intrusions to gain insights on the tectonic and metallogenic evolution of the region. Our data reveal at least two magmatic pulses in Lunggar represented by Early Cretaceous I-type granodiorite (112.9 ± 1.5 Ma) and granite porphyry (112.6 ± 1.3 Ma) with magma generation related to slab break-off associated with the Bangong–Nujiang Ocean during closure of the Meso-Tethyan ocean at ~113 Ma. Iron skarn mineralization at Lunggar was contemporaneous with local Early Cretaceous intrusive activity. Following this, Late Cretaceous adakitic diorite (90.5 ± 1.5 Ma) formed from delaminated thickened crust at ~91 Ma related to the northern subduction of the Yarlung-Zangbo oceanic plate. We also provide a comprehensive review of the Cretaceous tectonic evolution of Central Lhasa, which trace the tectonic evolution as follows: (a) 145–120 Ma: southward subduction of the Bangong–Nujiang oceanic plate under the Lhasa terrane; (b) 120–115 Ma: Lhasa-Qiangtang continental collision; (c) 115–110 Ma: slab break-off of the Bangong–Nujiang Ocean; (d) 110–95 Ma: crustal thickening of the Central Lhasa lower crust; (e) 95–80 Ma: delamination of lithospheric mantle; and (f) 80–65 Ma: northward subduction of the Yarlung-Zangbo oceanic plate and subsequent slab rollback. The related metallogenic events in Central Lhasa include (a) ~115–110 Ma skarn Fe mineralization associated with slab break-off; (b) ~90–80 Ma porphyry Cu–Au mineralization formed in delaminated thickened crust of Central Lhasa; and (c) ~65 Ma skarn Pb–Zn mineralization produced from slab rollback of the Yarlung-Zangbo Ocean.

Original languageEnglish
Pages (from-to)2323-2346
Number of pages24
JournalGeological journal
Volume54
Issue number4
Early online date10 Aug 2018
DOIs
Publication statusPublished - 1 Jul 2019

Keywords

  • Central Lhasa
  • Cretaceous magmatism
  • Lunggar Fe deposit
  • metallogenesis
  • tectonic evolution

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