Detrital zircons from Late Paleozoic to Triassic sedimentary rocks of the Gongshan-Baoshan Block, SE Tibet: Implications for episodic crustal growth Eastern Gondwana

The Gongshan-Baoshan Block is a segment of the northern Sibumasu Terrane, which is a continental strip derived from Eastern Gondwana. However, the formation history of the Gongshan-Baoshan Block and its relationship with other East Gondwana-derived blocks remain unclear. Here, we present five hundred and eighty new analyses of U-Pb ages of detrital zircons from Late Paleozoic to Triassic sedimentary rocks in the Gongshan-Baoshan Block, western Yunnan. The detrital zircon age spectra show distinctive age clusters at 2500-2400 Ma, 1750-1500 Ma, 1200-900 Ma, 600-500 Ma, with a few Archean ages of 3500-2600 Ma, suggesting secular, episodic, continental growth. The age spectra are comparable to those from the Sibumasu Terrane, Australia, Lhasa Block, Qiangtang Block, Tethyan High Himalaya and Cathaysia Block. We confirm that the GongshanBaoshan Block and Sibumasu Terrane could have occupied a position outboard of the Lhasa Block and close to northern India, along the northwestern margin of Australia in East Gondwana. The youngest ages from the Mesozioc sediments limit the timing of subduction of the Paleo-Tethys Ocean, which initiated by similar to 273 Ma and finally stopped at similar to 223 Ma.