Late Neoproterozoic-early Paleozoic tectonic evolution and paleogeographic reconstruction of the eastern Tibetan Plateau: A perspective from detrital zircon U–Pb-Hf isotopic evidence

Abstract

The Yidun Terrane, sandwiched between the Qiangtang and Songpan-Ganze terranes, hosts important information on the tectonic evolution of the eastern Tibetan Plateau. However, its tectonic link with adjacent terranes and East Gondwana remains equivocal. Here, we present U-Pb-Hf isotopes of detrital zircons from the upper Neoproterozoic-lower Paleozoic clastic rocks in the Yidun Terrane. The results show that detrital zircons from the Neoproterozoic rocks are mainly of ca. 821 – 890 Ma, 1714 – 1977 Ma, and 2317 – 2520 Ma, with εHf(t) values of each group comparable to coeval magmatic rocks in the nearby South China Block. This suggests that the Yidun Terrane and South China were possibly connected in the late Neoproterozoic, with the latter being the main sedimentary provenance. In contrast, the five Paleozoic samples have markedly different detrital zircon age spectra at ca. 2600 – 2300 Ma, 1100 – 900 Ma, 900 – 740 Ma, and 690 – 480 Ma, which were interpreted to have derived from Pan-African and Grenville-age provinces in the East Gondwana, as well as the South China Block and Songpan-Ganze Terrane. Such a major change on provenance suggests that after prolonged isolation in the Proto-Tethys, the Yidun Terrane began to collide with the East Gondwana in late Ediacaran to early Paleozoic. Integrated with published works, we consider that the Yidun Terrane, along with Songpan-Ganze Terrane and Yangtze Block, was located on the northern margin of East Gondwana during the early Paleozoic.