The Amoeboceras faunas in the Middle Oxfordian - lowermost Kimmeridgian, Submediterranean succession, and their correlation value

Abstract

The Amoehoceras faunas occurring at certain, but well documented biostratigraphically levels of the Submediterranean succession provide arguments for closer correlation of the Submediterranean zonal scheme with the Boreal and Subboreal ones. The conclusions are: (1) The boundary between the Boreal Tenuiserratum and Glosense Zones, i.e. the boundary between the Boreal Middle and Upper Oxfordian is recognized within the lower part of the Wartae Subzone of the Submediterranean Transversarium Zone, (2) The upper part of the Submediterranean Transversarium Zone correlates mostly with the upper part of the Boreal GIosense Zone, (3) The uppermost part of the Submediterranean Bifurcatus Zone correlates with the upper part of the Boreal Regulare Zone, (4) The lower part of the Submediterranean Bimammatum Zone correlates with the lower part of the Boreal Rosenkrantzi Zone, (5) The lowermost part of the Submediterranean Planula Zone correlates partly at least with the upper part of the Boreal Rosenkrantzi Zone, (6) The major part of the Submediterranean Planula Zone correlates with the lower part of the SubboreaI Baylei Zone, (7) The lower part of the Submediterranean Platynota Zone correlates with the upper part of the Subboreal Baylei Zone. The conclusions (6) and (7) indicate, moreover, that the boundary between the Oxfordian and Kimmeridgian is actually drawn higher in the Submediterranean zonal scheme (i.e. between the Planula and Platynota Zones), than in the Subboreal (i.e. between the Pseudocordata and Baylei Zones) and Boreal ones (i.e. between the Rosenkrantzi and Bauhini Zones).