Lower Cambrian acritarch stratigraphy of the Bårstad 2 core, Östergötland, Sweden

Abstract

Acritarch assemblages are described from basal Cambrian rocks in the Bårstad 2 core, Östergötland, southern Sweden. They can be compared with those employed for acritarch-based stratigraphy on the East European Platform. Hence, the Mickwitzia Sandstone is time equivalent with the Vergale stage, the lower part of the Lingulid Sandstone with the Rausve stage, while the top of the Lingulid Sandstone and the overlying glauconite sandstone are time equivalent with the Middle Cambrian Kibartai stage. The correlation of the acritarch zonation with the skeletal fossil zonation in Scandinavia is discussed. It is suggested that in Östergötland the Mickwitzia Sandstone can be referred to the Holmia inusitata Zone and the H. Kjerulfi-group Zone. The Lingulid Sandstone in Östergötland may belong to the Proampyx linnarssoni Zone or upper Lower Cambrian zones not prevously recorded in Scandinavia. The top of the Lingulid Sandstone and the overlying glauconite sandstone is referred to the lower Middle Cambrian Eccaparadoxides oelandicus Stage. Sedimentological and palynological data indicate that the studied sequence represents a condensed, but continuous sedimentation during the early and middle Cambrian. No major sedimentary break appears to exist neither between the Mickwitzia Sandstone and the Lingulid Sandstone, nor between the Lingulid Sandstone and the overlying glauconite sandstone. In this paper, two new genera and eight new species are described.

Key Words:

• Acritarchs
• stratigraphy
• Lower Cambrian
• Middle Cambrian
• Mickwitzia Sandstone
• Lingulid Sandstone
• glauconite sandstone
• glauconite sandstone
• Sweden