Precambrian crustal contribution to the Variscan accretionary prism of the Kaczawa Mountains (Sudetes,SW Poland): evidence from SHRIMP dating of detrital zircons |
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| Authors: | Ryszard Kryza Jan Zalasiewicz Stanis?aw Mazur Pawe? Aleksandrowski Sergey Sergeev Alexander Larionov |
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| Institution: | (1) Institute of Geological Sciences, Wrocław University, ul. Cybulskiego 30, 50-205 Wrocław, Poland;(2) Department of Geology, University of Leicester, University Road, Leicester, LE1 7RH, UK;(3) Center of Isotopic Research, A.P. Karpinsky All Russian Geological Research Institute (VSEGEI), 74 Sredny Pr, St Petersburg, 199 106, Russia |
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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 (∼2.0–3.4 Ga, the latter being the oldest recorded
age from the Sudetic region). These dates preclude within-terrane 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 (pre-Cadomian) 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 (post-Cadomian) rift
succession deposited at the northern margin of Gondwana, cannot yet be precluded. |
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| Keywords: | SHRIMP Zircon Precambrian Sudetes Variscides |
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