Heterogeneity of folding in Zechstein (Upper Permian) salt deposits in the Kłodawa salt structure, central Poland

Abstract

Analysis of folds carried out in the Kłodawa Salt Structure (central Poland) showed that the Upper Permian (Zechstein) siliciclastic-evaporitic succession is heterogeneously folded, resulting from differences in bed competence and stratigraphy. Rock salt and potash-rich successions of each Zechstein cycle are internally folded and contain multiple sheath folds, originated during lateral flow of salt at an early stage of deformation. These folds have been refolded by upright sheath folds within thick PZ1-PZ2 rock salt complexes. The lack of superposed folds in PZ3-PZ4 salt complexes and unconformities between the PZ1-PZ2 and PZ3-PZ4 units indicate that the rock salt beds were internally folded prior to diapirism, independently in each salt bed. The PZ1-PZ2 rock salt beds welded during lateral flow and were folded together into upright sheath folds during the upward flow of salt. These superposed folds clustered into subordinary diapirs and pierced through the younger deposits. The latter sunk in salt masses to form large-scale synclinoria, the strata of which contain early tectonic and weakly deformed sedimentary structures.