Continental margins in transition: how did northern Gondwana change from subduction to a shelf?

New U-Pb detrital zircon ages obtained in collaboration with Goethe University (Frankfurt am Main, Germany) and Czech Academy of Sciences from siliciclastic rocks of the Central Bohemian Massif document an intriguing example of how protracted and complex may be a transformation of an active plate margin, controlled by subduction of an oceanic plate, to a passive continental shelf. The northern rim of the supercontinent Gondwana underwent this transition during the late Neoproterozoic to Cambrian times. In their plate-tectonic reconstruction, Hajná et al. assigned a key role to obliquity of the oceanic subduction and impingement of a hot oceanic ridge into the deep sea trench, emhasizing the analogy with modern geotectonic settings.

Hajná J., Žák J., Dörr W., Kachlík V., Sláma J. (2018): New constraints from detrital zircon ages on prolonged, multiphase transition from the Cadomian accretionary orogen to a passive margin of Gondwana. Precambrian Research 317, 159-178. (DOI)