Boreal and Subboreal ammonites in the Submediterranean uppermost Oxfordian in the Bielawy section (northern Poland) and their correlation value

Abstract

The youngest deposits exposed in the Bielawy Quarry (Kujawy area, northern Poland) yielded both Submediterranean ammonites, making possible recognition of the uppermost Submediterranean Oxfordian, and Subboreal-Boreal ammonites, indicative of some parts of the Subboreal / Boreal lowermost Kimmeridgian. This makes possible closer correlation of the different zonal schemes that appear to be important in discussion of the uniform Oxfordian/Kimmeridgian boundary and recognition of its GSSP. The upper part of the Submediterranean Planula Subzone yields Boreal Amoeboceras of the Plasmatites group, indicative of the Boreal Bauhini Zone. Moreover, the lowermost part of the Submediterranean Galar Subzone corresponding to the wenzeli horizon yields Boreal Amoeboceras of the Amoebites group (such as Amoeboceras bayi BIRKELUND & CALLOMON), indicative of the lowermost part of the Boreal Kitchini Zone, as well as late representatives of the genus Pictonia, described here as Pictonia kuiaviensis sp. nov., allowing correlation with the upper part of the Subboreal Baylei Zone.