Early to Middle Ordovician strata, including Wenquan quartzite, occur widely in the Himalaya, Lhasa, and south Qiangtang blocks. The Wenquan quartzite occurs on the south side of the Lungmuco-Shuanghu Suture in the Qiangtang area, Tibet. A total of 145 analyses on detrital zircons from the quartzite show five age ranges of 520-700, ca. 800, 900-1100, 1800-1900, and 2400-2500 Ma, with particularly distinct age peaks of 625 and 950 Ma. The reliable youngest detrital zircon age is 525 Ma, and the oldest, 3180 Ma. Detrital zircons show large variations in Hf isotope composition, with depleted mantle model ages t DM (Hf) ranging from 750 to 3786 Ma. Based on data obtained in this study and by others, the main conclusions are as follows: 1) Low-grade metamorphic sedimentary rocks are distributed extensively in the south of the Lungmuco-Shuanghu Suture and are Phanerozoic in age; 2) Pan-African and Grenville-Jinning tectono-thermal events were well developed in the source region of the Wenquan quartzite; 3) the source region shows crustal addition and recycling of different periods; 4) Wenquan quartzite was derived from the Gondwana metamorphic basement, suggesting that the Qiangtang block is a Gondwanan fragment.
Gondwana, Tibetan Plateau, detrital zircon, SHRIMP dating, Hf isotope, Pan-African movement, Grenville-Jinning movementCitation: Dong C Y, Li C, Wan Y S, et al. Detrital zircon age model of Ordovician Wenquan quartzite south of Lungmuco-Shuanghu Suture in the Qiangtang area, Tibet: Constraint on tectonic affinity and source regions.Arising from the wide application of in situ U-Pb dating techniques such as by the SHRIMP ion microprobe, age distribution model studies of detrital zircons from (meta-) sedimentary rocks play more and more important roles in tracing the source region of detrital materials, understanding the evolution of ancient basement, determining the formation age of sedimentary rocks, and revealing the tectonic affinity of different blocks. The low-grade metamorphic Wenquan quartzite of the Early to Middle Ordovician age is the oldest geological body recently identified in the south side of the Lungmuco-Shuanghu Suture, central Tibetan Plateau. This paper reports U-Pb ages and Hf isotope compositions of detrital zircons of the quartzite in order to better understand the source characteristics and tectonic affinity of the Southern Qiangtang block.