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Figure S1. Zircon CL

The Southern Irumide Belt (SIB) is an orogenic belt consisting of a number of lithologically varied Mesoproterozoic and Neoproterozoic terranes that were thrust upon each other. The belt lies along the southwest margin of the Archaean to Proterozoic Congo Craton, and bears a Neoproterozoic tectono-thermal overprint relating to the Neoproterozoic–Cambrian collision between the Congo and Kalahari cratons. It preserves a record of about 500 million years of plate interaction along this part of the Congo margin. Detrital zircon samples from the SIB were analysed for U–Pb and Lu–Hf isotopes, as well as trace element compositions. These data are used to constrain sediment-source relationships between SIB terranes and other Gondwanan terranes such as the local Congo Craton and Irumide belt and wider afield to Madagascar (Azania) and India. These correlations are then used to interpret the Mesoproterozoic to Neoproterozoic affinity of the rocks and evolution of the region. Detrital zircon samples from the Chewore–Rufunsa and Kacholola (previously referred to as Luangwa–Nyimba) terranes of the SIB yield zircon U–Pb age populations and evolved εHf(t) values that are similar to the Muva Supergroup found throughout eastern Zambia, primarily correlating with Ubendian–Usagaran (ca. 2.05–1.80 Ga) phase magmatism and a cryptic basement terrane that has been suggested to underlie the Bangweulu Block and Irumide Belt. These data suggest that the SIB was depositionally connected to the Congo Craton throughout the Mesoproterozoic. The more eastern Nyimba–Sinda terrane of the SIB (previously referred to as Petauke–Sinda terrane) records detrital zircon ages and εHf(t) values that correlate with ca. 1.1–1.0 Ga magmatism exposed elsewhere in the SIB and Irumide Belt. We ascribe this difference in age populations to the polyphase development of the province, where the sedimentary and volcanic rocks of the Nyimba–Sinda terrane accumulated in extensional basins that developed in the Neoproterozoic. Such deposition would have occurred following late-Mesoproterozoic magmatism that is widespread throughout both the Irumide and Southern Irumide Belts, presently considered to have occurred in response to collision between a possible microcontinental mass and the Irumide Belt. This interpretation implies a multi-staged evolution of the ocean south of the Congo Craton during the mid-Mesoproterozoic to late-Neoproterozoic, which ultimately closed during collision between the Congo and Kalahari cratons. Keywords: Detrital zircon geochronology, Tectonics, Hafnium isotopes, Zambia, Southern irumide belt, Irumide belt

Neoproterozoic tectonic geography was dominated by the formation of the supercontinent Rodinia, its break-up and the subsequent amalgamation of Gondwana. The Neoproterozoic was a tumultuous time of Earth history, with large climatic variations, the emergence of complex life and a series of continent-building orogenies of a scale not repeated until the Cenozoic. Here we synthesise available geological and palaeomagnetic data and build the first full-plate, topological model of the Neoproterozoic that maps the evolution of the tectonic plate configurations during this time. Topological models trace evolving plate boundaries and facilitate the evaluation of "plate tectonic rules" such as subduction zone migration through time when building plate models. There is a rich history of subduction zone proxies preserved in the Neoproterozoic geological record, providing good evidence for the existence of continent-margin and intra-oceanic subduction zones through time. These are preserved either as volcanic arc protoliths accreted in continent-continent, or continent-arc collisions, or as the detritus of these volcanic arcs preserved in successor basins. Despite this, we find that the model presented here still predicts less subduction (ca. 90%) than on the modern earth, suggesting that we have produced a conservative model and are likely underestimating the amount of subduction, either due to a simplification of tectonically complex areas, or because of the absence of preservation in the geological record (e.g. ocean-ocean convergence). Furthermore, the reconstruction of plate boundary geometries provides constraints for global-scale earth system parameters, such as the role of volcanism or ridge production on the planet's icehouse climatic excursion during the Cryogenian. Besides modelling plate boundaries, our model presents some notable departures from previous Rodinia models. We omit India and South China from Rodinia completely, due to long-lived subduction preserved on margins of India and conflicting palaeomagnetic data for the Cryogenian, such that these two cratons act as 'lonely wanderers' for much of the Neoproterozoic. We also introduce a Tonian-Cryogenian aged rotation of the Congo-São Francisco Craton relative to Rodinia to better fit palaeomagnetic data and account for thick passive margin sediments along its southern margin during the Tonian. The GPlates files of the model are released to the public and it is our expectation that this model can act as a foundation for future model refinements, the testing of alternative models, as well as providing constraints for both geodynamic and palaeoclimate models. Refereed/Peer-reviewed

The Omani basement is located spatially distant from the dominantly juvenile Arabian–Nubian Shield (ANS) to its west, and its relationship to the amalgamation of those arc terranes has yet to be properly constrained. The Jebel Ja'alan (NE Oman) basement inlier provides an excellent opportunity to better understand the Neoproterozoic tectonic geography of Oman and its relationship to the ANS. To understand the origin of this basement inlier, we present new radiogenic isotopic data from igneous bodies in Jebel Ja'alan. U–Pb and 40Ar/39Ar geochronological data are used to constrain the timing of magmatism and metamorphism in the jebel. Positive εHf and εNd values indicate a juvenile origin for the igneous lithologies. Phase equilibria modelling is used to constrain the metamorphic conditions recorded by basement. Pressure–temperature (P–T) pseudosections show that basement schists followed a clockwise P–T path, reaching peak metamorphic conditions of c. 650–700°C at 4–7.5 kbar, corresponding to a thermal gradient of c. 90–160°C/kbar. From the calculated thermal gradient, in conjunction with collected trace-element data, we interpret that the Jebel Ja'alan basement formed in an arc environment. Geochronological data indicate that this juvenile arc formed during Tonian time and is older than basement further west in Oman. We argue that the difference in timing is related to westwards arc accretion and migration, which implies that the Omani basement represents its own tectonic domain separate to the ANS and may be the leading edge of the Neoproterozoic accretionary margin of India.