The ammonite succession in the Middle Jurassic of East Greenland

Abstract

The ammonite sequence in the Middle Jurassic of central East Greenland is the most complete and detailed known in the Arctic so far, and has become a standard of reference for the whole of the Bo real Faunal Province. It is made up of some 37 distinguishable assemblages that characterize a time-ordered succession of discrete faunal horizons. This succession has been pieced together from over 80 recorded sections in Jameson Land lying between Scoresby Sund and Kong Oscars Fjord (70-72°N). It forms the biostratigraphic basis for the regional chronostratigraphy. The faunal assemblages are listed and described by reference to published illustrations in the literature. Faunas 1-23 are of pre-Callovian age and have no elements in common with their contemporaries in the classical regions of Europe. They still cannot be correlated with the European standard pre-Callovian chronozonations. Most of them must be of Bathonian age, although the earliest of them could well be, and probably are, even still Upper Bajocian. The Bathonian-Callovian boundary most probably lies some­where in faunas 24-26, which closely resemble those of the keppleri horizon at the base of the Callovian. Faunas 27-35 span the rest of th􀁋 Lower Callovian, while faunas 36 and 37 are the only evidence of Middle and Upper Callovian. The ammonites from Jameson Land previously described by Spath (I 932) are revised and assigned to their correct horizons. Of 11 new species, only one is formally named: Kepp/erites vardekloeftensis sp. nov., of latest Bathonian age.