Ichnosystematics of the lower permian invertebrate traces from the Collio and Mt. Luco Basins (North Italy)

摘要

The Lower Permian ichnofauna in the Collio Formation (Artinskian) in the Val Trompia (Brescian Prealps, North Italy) has been studied for a long time, but the studies have focused mainly on vertebrate prints. In this study, the invertebrate ichnofauna of the Collio Formation, and in the epiclastites of the Monte Luco Formation (Artinskian) cropping out in the Monte Luco area (Trentino Alto Adige region), is systematically analyzed for the first time. This ichnocoenosis consists of: Permichnium isp., Paleohelcura tridactyla, Diplichnites gouldi (Types A and B), Diplopodichnus biformis, Circulichnis montanus, Helminthopsis hieroglyphica, Gordia marina, Acripes cf. multiformis, Cruziana cf. problematica, Cochlichnus anguineus, Palaeophycus tubularis, Planolites isp. and ?Scoyenia isp. The ichnoassociation from the Collio Formation belongs to the Scoyenia ichnofacies, while that from the Mt. Luco Formation belongs to the Mermia ichnofacies. The latter, because of the lack of complete data, can be linked only to one of several submersion phases of the intravolcanic basin and is not referred to the complete continental Permian sequence in this zone. The composition of the ichnoassociation here analysed is similar to those of other European (especially France and Germany) and extra-European areas (especially North America and Argentina).