De mellankambriska oelandicuslagren på Öland : stratigrafi och faciestyper

Sammanfattning: The thesis deals with a drill core retrieved from northern Öland, Sweden, in 2010. The length of the core is c. 107 m and comprises an Ordovician and Cambrian succession. The middle Cambrian primarily consists of fossiliferous mudstone with thin siltstone beds. This part of the succession has collectively been referred to as the Oelandicus beds. It is relatively homogeneous in composition and cannot be subdivided into the Bårstad and Moss-berga members, which is know from other areas. It is richly fossiliferous except in the lower part. The fossil faunas are dominated by trilobites and brachiopods. Trilobites and a few agnostoids are restricted to the upper part of the Oelandicus beds. Trace fossils are common throughout the Oelandicus beds. The lower part has only yielded a few brachiopods. The trilobites in the upper part are dominated by paradoxidids (Acadoparadoxides and Eccaparadox-ides) and ellipsocephalids (Ellipsocephalus). Among the agnostoids, species of the genera Condylopyge, Ptychag-nostus and Peronopsis have been recorded. The record of trilobite A. pinus in the upper part of the Oelandicus beds indicates that this part belongs to the A. pinus Zone. Biostratigraphically significant species have not been recorded from the lower part of the Oelandicus beds, but a comparison with other drill cores from Öland suggests that it be-longs to the E. insularis Zone. The Oelandicus beds are overlain by a 5.65 meter thick interval (52.60‒46.95 m) of greenish-grey mudstone with beds of a calcareous siltstone. This interval seems to represent the Äleklinta Member, which forms the uppermost part of the Borgholm Formation. The transition between the Oelandicus beds and the Äleklinta Member is, however, gradual.