U-Pb single-grain dating of detrital zircon in the Cambrian of central Poland: implications for Gondwana versus Baltica provenance studies

A provenance study of detrital zircon has been carried out in Middle Cambri an sandstones from the Lysogory Unit (Holy Cross Mountains) and the East Eu ropean Platform (EEP, Baltica) to investigate the docking of terranes along the Trans-European Suture Zone (TESZ) during the Paleozoic. Paleontologica l evidence suggests that the Lysogory Massif is a peri-Gondwanan-derived te rrane which did not reach the Baltic realm before Ordovician times. For a c omparison with the adjacent sequence in the EEP, across the TESZ, we have a nalyzed samples from borehole Okuniew IG-1 (15 km east of Warsaw), which co ntains Baltic faunas. The age spectrum of the detritus in the Cambrian of t he Lysogory Massif (19 analyses) reflects input of sources with ca. 600 Ma, ca. 1.8-2.0 Ga, and > 2.5 Ga zircon ages. In the EEP (Okniew borehole; 19 analyses), the U-Pb data demonstrate input from sources with ca. 530-700 Ma , 1.0-1.2 Ga, 1.5 Ga, ca. 1.8-2.0 Ca, 2.2 Ga, and > 2.5 Ga zircon ages. Add itionally, in this borehole the crystalline basement has been dated at 1800 +/- 6 Ma. These new data show that Late Neoproterozoic zircon ages are not restricted to peri-Gondwanan sources and that provenance studies across th e TESZ are more complex than expected. (C) 2000 Elsevier Science B.V. All r ights reserved.