Late Maastrichtian foraminiferal response to sea-level change and organic flux, Central Graben area, Danish North Sea

Abstract

AbstractForaminiferal palaeoecological analyses were carried out on 124 upper Maastrichtian chalk samples from the M-10X and E-5X wells of the Danish Central Graben. The two wells demonstrate similar trends, with some notable differences. Both are strongly dominated by planktic foraminifers, of which the small, biserialHeterohelix globulosais by far the most common species. Based on variations within five significant, benthic foraminiferal morphogroups and the plankton/benthos ratio, eight specific foraminiferal intervals have been described. The faunal and palaeoenvironmental changes observed during the late Maastrichtian period were, in most places and especially in the lower part, not very distinct, and it is believed that the palaeoenvironment during the majority of the interval was a mostly stable, deep outer-shelf environment characterized mainly by pelagic sedimentation under temperate, suboxic conditions. More unstable conditions characterized the latest Maastrichtian. The analyses show that the sediments in the M-10X well were deposited in a generally deeper palaeoenvironment than those from E-5X. The influx of commonPseudotextularia elegans(three acmes), together with scattered specimens of the typical Tethyan speciesAbathomphalus mayaroensisandPseudoguembelina hariaensis(in E-5X only), indicate that relatively warm conditions prevailed, at least periodically, during the latest part of the late Maastrichtian in both areas.