EVIDENCE FOR A CALEDONIAN OROGENY IN POLAND

The Lower Palaeozoic tectonic history of central and eastern Europe is poorly understood because of extensive Variscan and/or Alpine reworki ng. The trace of the Tornquist Sea, the SE arm of the Lower Palaeozoic Iapetus Ocean, extended from NE Britain to Asia Minor. The site of th is ocean is constrained by the tectonostratigraphy and faunal provinci ality of Lower Palaeozoic inliers in northern Czechoslovakia, and sout hern Poland. In this paper, the collage of contrasting tectonostratigr aphic histories of terranes in the Lower Palaeozoic of Poland is revie wed. Fossil evidence demonstrates that the Holy Cross Mountains and th e Krakovian Belt display Lower Ordovician and Lower Devonian angular u nconformities. Faunal data suggest that the Tornquist Suture Zone must lie south of the Holy Cross and between Upper Silesia and the Barrand ian of the Czech Republic. Between these areas, in the Sudeten Mountai ns, a continental scale sinistral mylonite zone (along the fine of the Intra-Sudetic Fault) was periodically active between the Middle Ordov ician and the Upper Triassic. Various dismembered ophiolite, island ar e and batholith terranes from alongside the Intra-Sudetic Fault have O rdocivian and Silurian magmatic and metamorphic zircon isotopic and fo ssil ages. Thus the often stated view that deformation in the Sudetes is Variscan (i.e. post-Middle Devonian) must be called into question. It is proposed instead that the Tornquist Suture is located within the Sudeten mountains, and as in the Holy Cross Mountains, much of the ob served deformation is post-Cambrian and pre-Gedinnian in age, i.e. Cal edonian.