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Neoproterozoic Tectonics of Australia‐Antarctica and Laurentia and the 560 Ma Birth of the Pacific Ocean Reflect the 400 M.Y. Pangean Supercycle

J. J. Veevers, M. R. Walter and E. Scheibner
The Journal of Geology
Vol. 105, No. 2 (March 1997), pp. 225-242
DOI: 10.1086/515914
Stable URL: http://www.jstor.org/stable/10.1086/515914
Page Count: 18
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Neoproterozoic Tectonics of Australia‐Antarctica and Laurentia and the 560 Ma Birth of the Pacific Ocean Reflect the 400 M.Y. Pangean Supercycle
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Abstract

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 lapetus 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.

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