Evidence for a Caledonian orogeny in Poland

Abstract

The Lower Palaeozoic tectonic history of central and eastern Europe is poorly understood because of extensive Variscan and/or Alpine reworking. 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 this ocean is constrained by the tectonostratigraphy and faunal provinciality of Lower Palaeozoic inliers in northern Czechoslovakia, and southern Poland. In this paper, the collage of contrasting tectonostratigraphic histories of terranes in the Lower Palaeozoic of Poland is reviewed. Fossil evidence demonstrates that the Holy Cross Mountains and the Krakovian Belt display Lower Ordovician and Lower Devonian angular unconformities. Faunal data suggest that the Tornquist Suture Zone must lie south of the Holy Cross and between Upper Silesia and the Barrandian of the Czech Republic. Between these areas, in the Sudeten Mountains, a continental scale sinistral mylonite zone (along the line of the Intra-Sudetic Fault) was periodically active between the Middle Ordovician and the Upper Triassic. Various dismembered ophiolite, island arc and batholith terranes from alongside the Intra-Sudetic Fault have Ordocivian and Silurian magmatic and metamorphic zircon isotopic and fossil 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 observed deformation is post-Cambrian and pre-Gedinnian in age, i.e. Caledonian.

Single zircon ages and whole-rock Nd isotopic systematics of early Palaeozoic granitoid gneisses from the Czech and Polish Sudetes (Jizerské hory, Krkonoše Mountains and Orlice-Sněžník Complex)

“…Crustal thickening during this accretion/amalgamation process led to widespread regional metamorphism shortly after 500 Ma as documented by Pr Ïikryl et al (1996) and our age of~492 Ma for a cross-cutting microgranite dyke in the OrlickØ hory. Finally, our data support the concept of a Caledonian orogeny in the West Sudetes (Johnston et al 1994), although much of the evidence was obliterated during the Variscan event. Table 4.…”

Proterozoic and Cambrian successions in Upper Silesia: an Avalonian terrane in southern Poland

“…The (Moczydłowska, 1996), that is, the Intra-Sudetic Fault as interpreted by Johnston et al (1994). The Upper Silesia terrane appears to be a crustal block bound by three sutures: the Caledonian (that is, K-MFZ, as interpreted by Moczydłowska, 1996), the Variscan (M-SF, according to Kotas, 1982a), and the Alpine (Peri-Peninian Fracture; Kotas, 1982a).…”

The Tepla(?)/Saxothuringian suture in the Karkonosze–Izera massif, western Sudetes, central European Variscides

“…The latter opinion further evolved into a division of the West Sudetes into the older, Caledonian' part, south of the Intra±Sudetic fault zone, and the younger,`Variscan' part, north of the fault zone (Lugicum and Sudeticum, respectively;Don 1984Don , 1990). More recent interpretations invoke a number of variously defined tectonostratigraphic terranes in the West Sudetes, either showing close affinities to the major tectonic provinces of the Variscan orogen (Matte et al 1990;Aleksandrowski 1990Aleksandrowski , 1995Franke et al 1993) or, at least in part, exotic with respect to the remaining parts of the Variscides (Oliver et al 1993;Cymerman and Piasecki 1994;Johnston et al 1994). From among the various models, the hypothetical terrane interpretation proposed by Matte et al (1990) and Matte (1991; see also Matte 1998) in many respects seems to fit best (though not perfectly) the field relationships in the West Sudetes, in particular within the Karkonosze±Izera massif.…”