The North Lhasa terrane in Tibet was attached with the Gondwana before it was drafted away in Jurassic: Evidence from detrital zircon studies

Abstract

It was commonly accepted that the North Lhasa terrane of the present-day central Tibetan Plateau in Asia came from the northern Gondwana, but the timing of its northward drifting away from the Gondwana remains controversial. Here we present for the first time U–Pb age and Hf isotope data on detrital zircons from the Cambrian metasedimentary rocks in the North Lhasa terrane. The detrital zircons display age peaks at ca. 505, 548, 926, and 1104 Ma, and are interpreted to have Gondwanan source regions. These metasedimentary rocks were probably deposited in a collisional tectonic setting (e.g., foreland basin) related to the Cambrian collisional accretion of microcontinents along the Gondwanan proto-Tethyan margin. The Cambrian and Carboniferous–Late Triassic sedimentary rocks in the North Lhasa terrane share the similar Precambrian–Cambrian detrital zircon age and εHf(t) distributions, indicating constant source accretion during the Cambrian–Triassic time. By contrast, the Precambrian–Cambrian detrital zircon age distribution of the Late Jurassic–Early Cretaceous sedimentary rocks in the North Lhasa terrane is distinctive from that of the adjacent Cambrian–Triassic sedimentary rocks, suggesting that the northward drifting of this terrane occurred in the Jurassic.