Wpływ paleomorfologii stropu białego spągowca na zmienność facjalną serii złożowej w Zagłębiu Lubińskim
Abstract
Palaeomorphology of Weissliegendes top as the control on facies variability in ore-bearing series of Lubin Copper-field, southwestern Poland
Abstract
In the study area the top of Weissliegendes displays remnant palaeomorphological features, among which are evidenced several elevations. A relationship between this palaeorelief and the assemblage of sedimentary facies of copper-bearing series and underlying lower Weissliegendes is pointed out. Within the elevations the ore-bearing series lacks the characteristic copper-shale (Kupferschiefer) deposits, and also displays relatively higher variability of carbonate-rock facies. Also the uppermost Weissliegendes, which belong to the ore-bearing series too, show higher variability of facies within the elevations than outside them. The elevations are typified by relatively greater thicknesses of the Weissliegendes, and also by considerably greater thicknesses of the entire zone of copper mineralization.
Within the Weissliegendes, four facies of deposits have been distinguished as related to different palaeoenvironmental settings. Large-scale cross-stratified sandstones are thought to have been the result of Early Permian aeolian sedimentation.
Subsequent (Zechstein) marine transgression, by encroaching upon the areas of aeolian sedimentation, led to partial demolition of the aeolian dunes and consequently produced two additional sandstone facies: laminated sandstones and „structureless” sandstones. Fourth facies is represented by the sandstones showing variety of sedimentary structures, among which are tabular and through cross--stratification, horizontal discontinuous and lenticular stratification, ripples, and waves, erosional channels, and deformational structures; this sandstone facies is thought to have originated in sublitoral environment, shortly after partial smoothing of the basin floor topography. Lateral interfingering of this sandstone facies with the copper-shale deposits seems to suggest a shallow-marine origin of these latter shales.