Abstract What drives the breakup of a supercontinent remains contentious. Previously proposed mechanisms include mantle plumes, subduction retreat and basal traction from mantle convection. Here we review the geological record of plumes, orogens and subduction zones during the breakup of Pangaea and investigate the potential roles played by these factors through 4D spherical geodynamic modelling. We found that mantle plumes provided the dominant force that drove the breakup of Pangaea, particularly in triggering the initial breakup. Young orogens as continental lithospheric weak zones generally guided the development of continental rifts, consistent with the geological record that rifting within Pangaea commonly developed along pre-existing orogens. However, the marginal drag force produced by subduction retreat, and basal traction associated with subduction-related mantle flow, likely also played a role in the breakup of Pangaea. In addition, the weakening effect of plume-induced melts can sometimes help to break the continental lithosphere away from orogens, as exemplified by the breakup between Antarctica and Australia. Furthermore, geodynamic modelling suggests that subduction is responsible for generating mantle plumes. A particular such example is the formation of the Kerguelen plume, triggered by subduction along the northern margin of Australia, which facilitated the breakup between East Antarctica and Australia.

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.

Abstract We present new palaeomagnetic data from two generations of mafic dykes in the Yanbian region of the western South China Block, dated by the zircon U–Pb method at 824±6 and 806±8 Ma, respectively. The primary origin for the characteristic remanent magnetizations is supported by a positive baked contact test, a dyke-tilt test and rock magnetic data. After tilt corrections, 10 dykes from the c. 824 Ma group gave a mean remanent direction of D =230.1°, I =−72.6° with k =16.3 and α 95 =12.3°, corresponding to a palaeopole at 42.5 °N, 131.8 °E with A 95 =19.0°. Three dykes from the c. 806 Ma group give a mean direction of D =284.5°, I =42.6° with k =76.5 and α 95 =14.2, corresponding to a virtual geomagnetic pole (VGP) at 18.2 °N, 31.0 °E with A 95 =20.4°. After correcting for a 5° vertical-axis rotation of the study region, the two pole positions are at 45.1 °N, 130.4 °E and 14.1 °N, 32.5 °E, respectively. The c. 825–720 Ma palaeopole position from South China, East Svalbard and neighbouring continents fall on great circles on two alternative Rodinia reconstructions, possibly reflecting oscillating inertial interchange true polar wander events (IITPWs).