Salt biostratigraphy: The Miocene palynological assemblages from the Wieliczka Formation, southern Poland

Abstract

Salt biostratigraphy has rarely been used in academic or industry studies, despite its potential to shed light on the stratigraphy, thermal maturity, paleoenvironments, and paleoecology of evaporite successions. The upper section of the evaporite-dominated middle Miocene Wieliczka Formation in southern Poland was sampled and analyzed for its palynological content. The results show assemblages dominated by miospores with subordinate dinoflagellate cysts, which are interpreted as derived mainly from reworking. The reworked forms, both miospores and dinoflagellate cysts, were sourced from Cretaceous, Paleogene, and Miocene strata, with increasing amounts toward the top of the succession, which is interpreted to be a consequence of the nearby ongoing Carpathian thrusting. The influence of marine water in the basin sedimentation is difficult to estimate with the current data as the dinoflagellate cysts are, at least partially, reworked. The in situ miospore assemblages indicate the presence of nearby mixed coniferous and broadleaved deciduous forests that developed under temperate and humid climatic conditions. The high percentages of bisaccate pollen are interpreted to represent the proximity to high-elevation areas of the Carpathians, where conifers must have been dominant. The palynological record also signals the development of swamp and marsh vegetation in the lowland areas. These wetlands were most likely inhabited by shrubby and arboreal elements with few thermophilic taxa. The apparent thermal maturation of the assemblages is very low, with dominant pale yellow palynomorph colors. The study shows that palynological analyses in evaporite-dominated successions are helpful in the reconstruction of local geodynamic events, paleoecology, and stratigraphic interpretation.