Remarks on the Permian-Triassic transition in Central and Eastern Lombardy (Southern Alps, Italy) Apuntes sobre el tránsito Pérmico-Triásico en Lombardía central y oriental (Alpes Meridionales, Italia)

The main lithological and petrographical characteristics of the Permian-Lower Triassic Orobic and Brescian successions in central and eastern Lombardy are briefl y recorded, especially with regard to the units cropping out below and above the P-T boundary. The lower formation is represented by the Verrucano Lombardo, which consists of continental, fl uvial red clastics, barren of fossils, generally Late Permian (Lopingian) in age, whereas the overlying Servino Formation, which is represented by well-bedded clastic and carbonate polychrome sediments, generally rich in fossils, pertains to the Early Triassic (Induan-Olenekian). The sequences of the two above-mentioned areas differ at least in part, as proof of their regional division, probably because of an inherited paleotopography and syntectonic activity. Taking into account the units bracketing the P-T boundary, which represents the real topic of this work, the Verrucano Lombardo of the Orobic Alps is paraconformably covered by the conglomerates and sandstones of the Prato Solaro Member in the lower part of the Servino Formation, cropping out extensively, although discontinuously, from the eastern side of Lake Como to the upper Scalve Valley in the Camonica region. The shape of some quartz rock fragments, derived from the Variscan crystalline basement and its Upper Carboniferous siliciclastic cover, has been interpreted as due to relatively coeval aeolian activity, and testifi es to an arid climatic “event” probably late Dienerian-early Smithian in age. In contrast, in the Brescia province, the onset of the Servino is made up of wave and current rippled, fi ne clastics, 1-2 m thick, and a typical horizon of oolitic dolostones (“Praso Limestone” Auct.), continuous from the lower Camonica Valley to the western Trentino. This unit could laterally correlate towards east, in the eastern South-Alpine segment, with the famous oolitic Tesero Member at the base of the Werfen Formation of the Dolomitic and Carnic Alps. In the Brescian Prealps, the above oolitic deposits crop out