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

Abstract

A provenance study of detrital zircon has been carried out in Middle Cambrian sandstones from the Lysogory Unit (Holy Cross Mountains) and the East European Platform (EEP, Baltica) to investigate the docking of terranes along the Trans-European Suture Zone (TESZ) during the Paleozoic. Paleontological evidence suggests that the Lysogory Massif is a peri-Gondwanan-derived terrane which did not reach the Baltic realm before Ordovician times. For a comparison with the adjacent sequence in the EEP, across the TESZ, we have analyzed samples from borehole Okuniew IG-1 (15 km east of Warsaw), which contains Baltic faunas. The age spectrum of the detritus in the Cambrian of the Lysogory Massif (19 analyses) reflects input of sources with ca. 600 Ma, ca. 1.8^2.0 Ga, and s 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 Ga, 2.2 Ga, and s 2.5 Ga zircon ages. Additionally, 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 periGondwanan sources and that provenance studies across the TESZ are more complex than expected. fl 2000 Elsevier Science B.V. All rights reserved.