| Summary: | Detrital zircons in Neoproterozoic–Paleozoic basins of the Pacific-Gondwana (PG) region contain a distinctive 700–500 Ma population conventionally considered to be derived from Antarctica. However, the 700–600 Ma age component of the population predates major peripheral orogenesis (Terra Australis orogen), which began at ca. 580 Ma, and the highly evolved ɛ Hf(t) -in-zircon values (to −40) require an Archean source, which is not proximal to the Terra Australis active margin. Based on similar ɛ Hf(t) arrays defined by Neoproterozoic granites in Western Australia and detrital zircon populations from the surrounding basins, we suggest that PG zircon grains were derived from the >2000-km-long, late Neoproterozoic Paterson-Petermann orogen, which sutured northern and southern Australia at 550–530 Ma. This Himalayan-style orogen was responsible for amalgamating Southeast Asian terranes into northeast Gondwana, thereby constraining the paleogeography of the northern Gondwanan margin at the Precambrian-Cambrian boundary. Remarkable isotopic similarity of zircon grains with the Lhasa terrane of Tibet suggests that the Paterson-Petermann orogen was the eastern sector of the developing circum-Gondwana subduction system from ca. 700 Ma.
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