The early Cenomanian crippsi Event at L\xfcneburg (Germany): palaeontological and stratigraphical significance of a widespread Late Cretaceous bioevent

Abstract

The early Cenomanian crippsi Event comprises a 1–3-m-thick interval characterised by mass occurrences of the early Cenomanian inoceramid Gnesioceramus crippsi, identified in the uppermost Sharpeiceras schlueteri Subzone (lower lower Cenomanian Mantelliceras mantelli Zone), below an interregional sequence boundary (SB Ce 1). At Lüneburg, the event is characterised by densely packed, very large, disc-like valves of G. crippsi. Taphonomy as well as bio- and microfacies suggest an event formation in a deeper shelf setting below the storm-wave base as primary biogenic concentration, the inoceramids living as recumbent forms on a soft substrate in dense populations. When tracked between basins, the stratigraphic pattern of the crippsi Event suggests a moderately prolonged phase (< 100 kyr) of increased shell production with rapid deposition aiding in preserving the shell-rich event strata. Towards the basin margins, it grades into storm wave-reworked bioclastic concentrations. The crippsi Event formed by an interregional population bloom and provides, as an proliferation epibole, an important marker for intra- and interbasinal correlation. The first record of G. mowriensis within the crippsi Event at Lüneburg, hitherto endemic to the US Western Interior Seaway, and the occurrence of the ammonite Metengonoceras teigenense, likewise an endemic North American faunal element, from the level of the crippsi Event in northern France indicate faunal exchange between the New and Old worlds during the early Cenomanian. This faunal dispersal and contemporaneous occurrence of warm-water biofacies in Western Europe during the early Cenomanian is explained by the existence of a perpetual NE-directed current transporting warm surface waters from the Gulf of Mexico towards Europe. The occurrence of short-lived M. teigenense in France allows for the calibration of the uppermost schlueteri Subzone of the mantelli Zone in Europe to the lowermost Neogastroplites muelleri Zone in North America and to assign an age of ~ 98.6–98.7 Ma to the crippsi Event.