Precambrian crustal contribution to the Variscan a

Authors: Ryszard Kryza Jan Zalasiewicz Stanisław Mazur Paweł Aleksandrowski Sergey Sergeev Alexander Larionov

Publish Date: 2006/12/12

Volume: 96, Issue: 6, Pages: 1153-1162

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Abstract

SHRIMP dating of detrital zircons from sandstones of the Gackowa Formation Kaczawa Complex Sudetes SW Poland indicates input from late 550–750 Ma and early Proterozoic to Archaean sources ∼20–34 Ga the latter being the oldest recorded age from the Sudetic region These dates preclude withinterrane derivation from seemingly correlatory acid volcanic rocks of early Palaeozoic age Rather they indicate provenance from Cadomian and older rocks that currently form part of other geographically distant terranes the most likely source identified to date is the Lusatian Block in the Saxothuringian Zone Hence the Gackowa Formation may be late Proterozoic rather than early Palaeozoic in depositional age possibly coeval with the late Proterozoic preCadomian greywackes of Lusatia being subsequently tectonically interleaved with early Palaeozoic volcanic rocks into the Kaczawa accretionary prism during the Variscan orogeny However correlation with the lithologically similar early Ordovician Dubrau Quartzite of Saxothuringia and so assignation to the early Paleozoic postCadomian rift succession deposited at the northern margin of Gondwana cannot yet be precludedWrocław University Internal Grant 2022/W/ING/05 provided funds for the SHRIMP study Maciek Kryza helped in preparing computerized figures The mounting and preparation of zircons was done by Anna Saltykova CIR VSEGEI Ulf Linnemann and an anonymous reviewer are thanked for their constructive comments

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