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1 Geotourism / Geoturystyka

1 2023

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Detrital zircon populations in Ediacaran Period sediments distinguish active from passive continent margins even when metamorphosed and help resolve the Gondwana-Panotia supercontinent/megacontinent argument

Crow Michael, Zaw Khin, Thu Kyaw, Belousov Ivan, Goemann Karsten

Geotourism / Geoturystyka

2023

nr 1-2 (72-73)

16--17

Great thicknesses of sand and greywacke were deposited on the margins of megacontinents during the Ediacaran Period (620–542 Ma). Zircon age populations in sediments with long deep-time flat profiles distinguish passive margin sedimentation from shorter humped zircon profiles characteristic of sediments derived from volcanic arcs and their feeder zones in active margins. An example of a single hump detrital profile is given by an Ediacaran Period volcano present in the Charnian Supergroup in the Anglo-Brabant Massif of the East Avalonia terrane. This Gondwana fragment was originally part of the West Africa craton and was subsequently accreted to Laurentia. A volcanic complex with sediments carrying an Ediacaran biota is overlain by Triassic sediments. The main phase of eruption at c. 561 Ma provides a single hump zircon age histogram with a few pre-eruption zircon xenocrysts up to 40 Ma older