North-Gondwana assembly, break up and paleogeography: U–Pb isotope evidence from detrital and igneous zircons of Ediacaran and Cambrian rocks of SW Iberia (Estremoz Anticline)

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Abstract

The Estremoz Anticline in the Ossa-Morena Zone (SW Iberia) includes upper Ediacaran detrital rocks unconformably overlain by lower Cambrian detrital and carbonate rocks. The spectra of detrital zircon U–Pb ages dominated by Cryogenian and Ediacaran ages (with a typical gap in Mesoproterozoic ages) of the upper Ediacaran greywackes and lower Cambrian arkosic sandstones indicate provenance from sources placed near or at the North-Gondwana margin. These late Ediacaran and early Cambrian basins developed in a paleoposition close to the West African Craton and related to a long-lived Neoproterozoic magmatism (c. 850–700Ma — Pan-African suture; c. 700–635Ma — early Cadomian arc; and c. 635–545Ma — late Cadomian arc). The rhyolites of the Volcanic–Sedimentary Complex of Estremoz whose stratigraphic position so far has been a controversy, yielded an upper Cambrian age (Furongian) at about 499Ma indicating that carbonate production was episodic in SW Iberia during the Cambrian. This new evidence should be taken into account in the reshaping of paleogeographic reconstruction models that have erroneously insisted on placing Iberia at southerly cold water higher latitudes (>60°S) during the Furongian.
Original languageUnknown
Pages (from-to)866–881
JournalGondwana Research
Volume22
Issue number3-4
DOIs
Publication statusPublished - 1 Jan 2012

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