Gondwana’s interlinked peripheral orogens

Abstract

After its Ediacaran-Early Cambrian assembly, Gondwana was flanked by a system of peripheral orogens, Terra Australis, Avalonian-Cadomian and newly defined North Indo-Australie, which display broad temporal correlations of their lithotectonic records. Prior to assembly, their initial histories were primarily controlled by the early Neoproterozoic breakup of Rodinia with second order variances reflecting the differing relationships of their basement continental blocks to that supercontinent. The Terra Australis Orogen developed on basement blocks that previously occupied interior locations within Rodinia and initial successions record development of a passive continental margin. The North Indo-Australie orogen records a similar history of passive margin development, but at least its Indian portion was likely separate from Rodinia. The basement blocks of the Avalonian-Cadomian Orogen previously occupied exterior locations around Rodinia with initial successions indicating the development of a convergent plate margin. As Gondwana assembled, Avalonian-Cadomian convergence terminated at about the same time as convergence commenced in the Terra Australis and North Indo-Australie orogens. The absence of a complete long-lived contemporaneous subduction girdle around Gondwana likely prevented its breakup, in contrast to Rodinia and Pangea, in which the presence of subduction girdles corresponds with lithospheric extension across the supercontinents as a precursor to their ultimate breakup.