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 Qi...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.展开更多
基金supported by Ministry of Land and Resources of the Peoples' Republic of China (Grant No. 1212010811033)National Natural Science Foundation of China (Grant Nos. 40672147, 40872146)
文摘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.
