Abstrakt
This paper describes palaeobotanical material discovered in new fossiliferous localities from the late Palaeozoic fluvio-lacustrine deposits of the Ollano Formation in the central part of the Ligurian Alps (north western Italy). Despite the tectono-metamorphic history that generally results in poor preservation of plant remains, abundant fossil plant specimens were preserved in less deformed portions of the rock succession.
The common presence of Neuralethopteris schlehanii (Stur, 1877) Laveine, 1967, Laveinopteris tenuifolia (Schlotheim ex Sternberg, 1825) Cleal et al., 1990 var. nordfrancia Cleal & Shute, 2003, Neuropteris obliqua (Brongniart, 1831) Zeiller, 1888, and Lyginopteris cf. L. baeumleri (Andrae, 1868) Gothan, 1913 provides time constraints for deposition of the Ollano Formation between the latest early Pennsylvanian and early middle Pennsylvanian, most probably within the late Bashkirian (Langsettian-early Duckmantian) with the assemblage corresponding to the Lyginopteris hoeninghausii/Neuralethopteris schlehanii fossil plant Zone.
Our new findings of plant fossils from this formation confirm an age very close to the late Westphalian, originally proposed by previous palaeobotanical studies. This indicates that further analyses are necessary in order to better constrain the primary relationship between the Ollano Fm. and the adjacent volcanics, whose radiometric dating to the early Permian is problematic.