Biostratigraphy of the Furongian (upper Cambrian) Alum Shale Formation at Degerhamn, Öland, Sweden

Abstract

The Furongian (upper Cambrian) Alum Shale at Degerhamn, southern Öland, Sweden, has been systematically sampled for macrofossils. Two sections were investigated, one in a large abandoned Alum Shale quarry and one in a nearby road section. The 6.25 m thick succession comprises the Olenus, Parabolina, Leptoplastus, Protopeltura and Peltura superzones. The Olenus gibbosus, Olenus truncatus, Olenus attenuatus, Parabolina spinulosa, Leptoplastus crassicornis–Leptoplastus angustatus, Sphaerophthalmus flagellifer, Ctenopyge tumida, Ctenopyge linnarssoni and Parabolina lobata zones have been identified in addition to the informal Olenus rotundatus and Sphaerophthalmus modestus zones. The informal Olenus rotundatus biozone is assumed corresponding in age to the Olenus scanicus Chronozone and the informal Sphaerophthalmus modestus biozone is assumed corresponding in age to the Ctenopyge (Mesoctenopyge) similis Chronozone; S. modestus has not previously been reported from Öland. The uppermost parts of the O. gibbosus, O. truncatus, P. spinulosa and C. tumida zones are reworked. Peltura minor may range into the basal C. linnarssoni Zone; alternatively it is also reworked. Ctenopyge (Ctenopyge) directa, Triangulopyge humilis, Triangulopyge major and Ctenopyge (Ctenopyge) fletcheri are here reported from the C. linnarssoni Zone; none of these species have previously been described from Öland. Furthermore, this zone yielded indeterminable fragments of ‘exotic’ non-olenid trilobites. The uppermost level preserved at Degerhamn is the Parabolina lobata Zone where common Peltura scarabaeoides westergaardi is recorded for the first time from this locality.