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 status of Pannotia as an Ediacaran supercontinent, or even its mere existence as a coherent large landmass, is controversial. The effect of its hypothesized amalgamation is generally ignored in mantle convection models claiming the transition from Rodinia to Pangaea represents a single supercontinent cycle. We apply three geodynamic scenarios to Pannotia amalgamation that are tested using regional geology. Scenarios involving quasi-stationary mantle convection patterns are not supported by the geological record. A scenario involving feedback between the supercontinent cycle and global mantle convection patterns predicts upwellings beneath the Gondwanan portion of Pannotia and the arrival of plumes along the entire Gondwanan (but not Laurentian) margin beginning at c. 0.6 Ga. Such a scenario is compatible with regional geology, but the candidates for plume magmatism we propose require testing by detailed geochemical and isotopic studies. If verified, this scenario could provide geodynamic explanations for the origins of the late Neoproterozoic and Early Paleozoic Iapetus and Rheic oceans and the terranes that were repeatedly detached from their margins.