Palaeontology and U–Pb detrital zircon geochronology of Upper Triassic strata on the northern margin of the Bangong Co–Nujiang suture zone, Tibet: Constraints on the age of opening of the Meso-Tethys. (15th May 2019)

• Record Type: Journal Article
• Authors: Wang, Ming; Peng, Shuai-Ying; Li, Cai; Zhang, Tian-Yu
• Is Part Of: Journal of Asian earth sciences. Volume 175(2019)
• Page Start: 26
• Page End: 34
• Publication Date: 2019-05-15
• Subjects: Tibet -- Bangong Co–Nujiang suture zone -- Gaerqin -- Late Triassic -- Coral fossils; Earth sciences -- Asia -- Periodicals; Sciences de la terre -- Asie -- Périodiques; Earth sciences; Asia; Periodicals; 555.05
• DOI: 10.1016/j.jseaes.2018.08.015
• Languages: English
• ISSNs: 1367-9120

Abstract

Graphical abstract: Highlights: The newly recognized strata in the Gaerqin area (Gaerqin Formation) formed in the Norian Stage of the Late Triassic. The Gaerqin Formation is the first reported Late Triassic Norian strata in the Duolong ore concentrating area of Tibet. The Bangong Co–Nujiang Tethys Ocean was already a bathyal basin before the Late Triassic. Abstract: We present the results of field mapping, paleontology, and detrital zircon geochronology of newly found clastic rocks with intercalations of limestone in the Gaerqin area of Tibet (Gaerqin Formation). The Gaerqin Formation consists of sandstone, siltstone, and shale with intercalations of bioclastic limestone. Abundant Late Triassic (Norian) fossils are found in the limestone beds. The fossils include Distichophyllia norica, Retiophyllia litangensis, and Mesozoic Chaetetida . In addition, 273 detrital zircons were selected for U–Pb dating, yielding the following age groups: 210–300, 500–600, 800–1100, 1600–1800, and 2400–2600 Ma. More than 80% of the detrital zircons are older than ∼550 Ma, and the most reliable youngest detrital zircon age for the Gaerqin Formation is ∼219 Ma. The results indicate that the Gaerqin Formation formed in a shallow marine to bathyal continental slope environment, and represents the first reported Upper Triassic (Norian) strata in the Gaerqin area of Tibet. The findings also suggest that the Bangong Co–Nujiang Tethys Ocean was a bathyal basin by the Late Triassic.