Neoproterozoic tectonics of Australia-Antarctica and Laurentia and the 560 Ma birth of the Pacific Ocean reflect the 400 m.y. Pangean supercycle

Unequivocal evidence for the Proterozoic reconstruction of Australia-Antarctica and Laurentia remains elusive, although various authors have interpreted sedimentary and igneous events in terms of initial (Neoproterozoic) rifting, and final (Neoproterozoic/Cambrian) drifting. The synchronous rifting and drifting reflect the tectonics of a late Neoproterozoic Pangea (East Gondwanaland and Laurentia) that amalgamated along the Mozambiquean belt ∼720 Ma and broke up at 560 Ma by growth of the Paleo-Pacific and Iapetus oceans. In this paper these events are interpreted as part of a 400 m.y. supercycle comparable to the 320 Ma amalgamation of Pangea A and its 160 Ma breakup during Supercycle A (320 Ma to present). Events near the end of the Cambrian (500 Ma) in East Gondwanaland included epeirogenic uplift of cratons, shown by widespread K/Ar and apatite fission-track dates, and the inception of quartz turbidite fans, intense deformation and intrusion by granite of the Antarctic and south-eastern Australian margins, followed by a global sea-level maximum. These events are comparable to the mid-Cretaceous (100-90 Ma) epeirogenic uplift of Australia, intrusion by granite of the western USA and elsewhere, followed by a second global sea-level maximum. Both supercycles were driven by pulses of supercontinent-induced heat that caused global rifting by extension, subsidence, and filling of sedimentary basins, followed by continental drifting and seafloor spreading. Our detailed compilation of the tectonic effects of Supercycle B (720-320 Ma) suggests that Pangea-induced heat has punctuated earth history since at least 720 Ma. The previous Pangean amalgamation, indicated by the global 1100 Ma (Grenvillian) deformation, suggests a third supercycle that introduced the modern regime of plate tectonics.