Abstract

The widespread Tibetan Permo-Carboniferous glaciogenic diamictites (PCGDs) are conventionally thought to be sourced from Indian Gondwana during glacier transport and deglaciation. However, the Lhasa PCGDs differ in detrital zircon U-Pb age spectra and ε_Hf(t) values from those in Southern Qiangtang and Tethyan Himalaya. The similarities in ε_Hf(t) values for similar-age detrital zircons, the development of glacier transport pathways, and the large volumes of the Tibetan PCGDs indicate an Australian source for the Lhasa PCDGs, and an Indian source for the Southern Qiangtang and Tethyan Himalayan PCDGs. We conclude that the Southern Qiangtang and Tethyan Himalayan are paleographically linked to northern India, whereas Lhasa is positioned adjacent to NW Australia during the Paleozoic. Magmatic and metamorphic records further indicate that eastern Lhasa (E90°–E95°) represents the outboard extension of events recorded in northern Central Australia, whereas western Lhasa (E80°–E90°) was located outboard of the West Australian Craton.

Plain Language Summary

Precisely understanding the paleogeography of the Lhasa Terrane in southern Tibet is crucial to reconstruct the opening and drifting histories of the Neo-Tethys that controls on the evolution of the India-Asia collision zone. The paleogeography of the Lhasa Terrane has been variously proposed to originate from northern India, northwest Australia, and the northern extent of the East African Orogen. Resolving this paleogeographic puzzle requires solid lines of evidence and a full understanding of the data. A combination of new detrital zircon U-Pb age and Hf isotope data of the Tibetan Permo-Carboniferous glaciogenic diamictites constrains the paleogeography of the Lhasa Terrane to a position adjacent to NW Australia. Magmatic and metamorphic records further refine that the eastern Lhasa (E90°–E95°) represents the outboard extension of events recorded in northern Central Australia, whereas the western Lhasa (E80°–E90°) was located outboard of the West Australian Craton. Our results show that a combination of provenance analysis (including magmatic history, isotopic data, and sediment transport pathway) of the widespread late Paleozoic diamictites in Gondwana, as well as magmatic and metamorphic records, can allow precise paleogeographic reconstruction of the longitudinal disposition of blocks along the northern Gondwana margin.

Article link: https://doi.org/10.1029/2021GL094236