Abstract
Periodic assembly and dispersal of continental fragments has been a characteristic of the solid Earth for much of its history. Geodynamic drivers of this cyclic activity are inferred to be either top-down processes related to near surface lithospheric stresses at plate boundaries or bottom-up processes related to mantle convection and, in particular, mantle plumes, or some combination of the two. Analysis of the geological history of Rodinian crustal blocks suggests that internal rifting and breakup of the supercontinent were linked to the initiation of subduction and development of accretionary orogens around its periphery. Thus, breakup was a top-down instigated process. The locus of convergence was initially around north-eastern and northern Laurentia in the early Neoproterozoic before extending to outboard of Amazonia and Africa, including Avalonia–Cadomia, and arcs outboard of Siberia and eastern to northern Baltica in the mid-Neoproterozoic (∼760 Ma). The duration of subduction around the periphery of Rodinia coincides with the interval of lithospheric extension within the supercontinent, including the opening of the proto-Pacific at ca. 760 Ma and the commencement of rifting in east Laurentia. Final development of passive margin successions around Laurentia, Baltica and Siberia was not completed until the late Neoproterozoic to early Paleozoic (ca. 570–530 Ma), which corresponds with the termination of convergent plate interactions that gave rise to Gondwana and the consequent relocation of subduction zones to the periphery of this supercontinent. The temporal link between external subduction and internal extension suggests that breakup was initiated by a top-down process driven by accretionary tectonics along the periphery of the supercontinent. Plume-related magmatism may be present at specific times and in specific places during breakup but is not the prime driving force. Comparison of the Rodinia record of continental assembly and dispersal with that for Nuna, Gondwana and Pangea suggests grouping into two supercycles in which Nuna and Gondwana underwent only partial or no break-up phase prior to their incorporation into Rodinia and Pangea respectively. It was only after this final phase of assembly that the supercontinents then underwent full dispersal.
Highlights
Profound influences on the evolution of Earth’s crust, atmosphere, hydrosphere and life have been exerted since the late Archean by repeated cycles of supercontinent amalgamation and dispersal (Nance et al, 2014; Worsley et al, 1986)
The aim of this paper is to demonstrate how collisional orogenic systems associated with the assembly of Rodinia at c. 1.0–0.9 Ga were followed by global plate adjustments that led to the development of accretionary orogens around a significant part of the supercontinent
Final development of passive margin successions around Laurentia, Baltica and Siberia was not completed until the end of the Neoproterozoic to early Paleozoic in the timeframe 570–530 Ma
Summary
Profound influences on the evolution of Earth’s crust, atmosphere, hydrosphere and life have been exerted since the late Archean by repeated cycles of supercontinent amalgamation and dispersal (Nance et al, 2014; Worsley et al, 1986) Key to evaluating these influences is the understanding of the relative timing of tectonic events within and between the different aspects of the Earth system, in the fragmentary rock archive of the Precambrian. Quantifying global changes in the movement of lithospheric plates and links to other aspects of the Earth system is only possible for the modern Earth with its relatively complete record of oceanic crust and seafloor spreading. The development of encircling subduction zones shuts off the mantle region in the centre of the supercontinent from subduction, often leading to rising hot mantle, which may facilitate break-up, development of plumes and hot spots is not a pre-requisite (Condie, 2005)
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