The lower and middle Pleistocene geological record of the San Lorenzo lacustrine succession in the Sant'Arcangelo Basin (Southern Apennines, Italy)

The Sant’Arcangelo Basin is located in the southern part of the Apennine chain (Basilicata). It is filled by a siliciclastic sequence3500m thick, dated to the Late Pliocene–Middle Pleistocene time interval. In this basin an Early Middle Pleistocene fluvio-lacustrinesequence, known as San Lorenzo Cycle, has been recognised. In the upper part of the sequence, in Rifreddo, a fairly diversified smallvertebrate assemblage has been recovered.The occurrence of Mimomys savini allows to the fauna to be considered as Biharian. The presence of some faunal elements such asMicrotus (Terricola) arvalidens, Microtus (Iberomys) ex gr. huescarensis-brecciensis, and Macroneomys cf. brachygnathus restricts theage of the Rifreddo assemblage to the latest part of this Mammal Age. In several European localities, sediments containing such lateBiharian faunas are correlated with the lower part of Brunhes magnetochrone (e.g. the normally magnetised sections at WestRunton in the United Kingdom, Voigtstedt in Germany and Prˇezletice in the Czech Republic) or just below this boundary (e.g. thenegatively magnetised part of the Atapuerca section—levels TD4-6 in Spain). Taking into account the faunal composition and thepositive magnetisation of the sediments outcropping at the Rifreddo locality, the chronological referral of the mammal assemblagecan be restricted to the early Brunhes and therefore to the early middle part of Middle Pleistocene.