Abstract An evaluation of the potential geodynamic connections between the evolution of Paleozoic oceans in NW Gondwana and NE Gondwana is challenging. Until recently, most syntheses emphasized only two Paleozoic oceans (the Proto-Tethys and the Palaeo-Tethys) in the east Tethys realm. However, the discovery of early Paleozoic ophiolites along Palaeo-Tethys sutures located south of Proto-Tethys sutures challenges these traditional views. After a comprehensive review of relevant early Paleozoic tectonomagmatic events, we herein recognize and propose a model for the tectonic evolution of a hitherto unrecognized early Paleozoic ocean, which we call the Proto-Qiangtang Ocean. This ocean was short lived; it opened in the late Cambrian, began to subduct in the Middle Ordovician, and closed diachronously westwards between the Late Ordovician and the middle Silurian. Its closure by middle Silurian time indicates that was a spatially and temporally distinct ocean from the Palaeo-Tethys Ocean. The early tectonic evolution of the Proto-Qiangtang Ocean shares many characteristics with that of the Rheic Ocean. Both opened in the late Cambrian in the back-arc region of the Iapetus–Proto-Tethys Ocean, and the Proto-Qiangtang Ocean is considered to represent the eastern extension of the Rheic Ocean. This correlation has important implications for the Paleozoic tectonic evolution and palaeogeography of northern Gondwana.

Abstract The geodynamic evolution of the Palaeo-Tethyan Ocean is key to understanding the development of Pangaea. The main continents of SE Asia were welded together in response to the closure of the Palaeo-Tethyan Ocean. However, the precise location of the sutures and timing of the collisions are poorly constrained, especially the southward continuation from Peninsular Malaysia into west Indonesia. This study presents new zircon U–Pb geochronological, petrological, elemental and Sr–Nd–Pb–Hf–O isotopic data in order to investigate the origin and tectonic setting of the granitoids from the Bangka and Belitung islands, west Indonesia. Although possessing different mineral compositions, the two groups of samples yield similar crystallization ages of c. 230–220 Ma and enriched Nd–Hf isotopic compositions (whole-rock ε Nd ( t ) = −9.6 to −2.4 and zircon ε Hf ( t ) = −12.1 to −0.1), and probably originated from melting of a mixed source of metagreywacke and metapelite with a subordinate meta-igneous component. Both granitic groups formed during post-collisional processes, and when this interpretation is combined with regional investigations on the granitic magmatism, the Bangka–Belitung granitoids may represent the southward continuation of the Main Range granitoids. If correct, the distribution of granitoids with distinct petrogenesis across both islands implies a location for the Palaeo-Tethyan suture zone between Bangka–Belitung and West Kalimantan.

Abstract The location of the Meso-Tethyan suture in SE Asia is ambiguous due to the strong overprint by the later India–Asia collisional tectonics. For the SE Asian extension of the Meso-Tethyan Bangong–Nujiang Suture (BNS) in Tibet, the two main candidates are the Longling–Ruili Suture (between the Tengchong and Baoshan blocks) and the Myitkyina ophiolite belt. Here, we present new detrital zircon U–Pb ages from high-grade metasedimentary rocks of the Gaoligong Group, which is considered to be the basement of the Tengchong Block located between the Longling–Ruili Suture and Myitkyina ophiolite belt. Our data suggest that the Gaoligong Group contains Cambrian, Triassic and Cretaceous zircons and is not a Precambrian basement, with a diagnostic age population peak at c. 1110 Ma. This peak is comparable to the c. 1170 Ma peak reported in the Australia-derived blocks (e.g. Lhasa and West Australia). Such similarities, as well as the similarities in the stratigraphy, palaeobiogeography and magmatic history of the Tengchong Block, suggest that the Tengchong Block was located adjacent to the northern Australia margin in Gondwana, and was most likely to have been linked with the Lhasa Block (southern Tibet) since the Early Paleozoic. Thus, the Longling–Ruili Suture is likely to represent a continuation of the Meso-Tethyan BNS in SE Asia.