Latest Cretaceous storm-generated sea grass accumulations in the Maastrichtian type area, the Netherlands – preliminary observations

Abstract Ever since the first description of fossil material during the mid-nineteenth century, sea grass has been shown to be quite commonly preserved in ‘pockets’ or ‘clumps’ at certain levels within the Gulpen, Maastricht and Kunrade formations in southern Limburg (the Netherlands) and contiguous areas in northeast Belgium. In those places where silicification occurred during early diagenesis, even completely silicified and three-dimensionally preserved stems and roots can be found, mostly of Thalassocharis bosquetii, in association with fully marine molluscs such as dentaliid scaphopods and a range of larger foraminifera, bivalves, gastropods and ammonites. Such occurrences are best known from the Valkenburg, Gronsveld and Emael members of the Maastricht Formation in the Eben Emael (Liege, Belgium) and Sint-Pietersberg (Maastricht, the Netherlands) areas. However, accumulations of sea grasses, littering the sea floor over a considerable areal extent, were never as well observed as in a gully-fill that was discovered and partly excavated in the uppermost Gronsveld Member at the ENCI-HeidelbergCement Group quarry in October 2015. Our preliminary results concern the palaeoenvironment and taphonomy of this deposit and identify some of the more notable members of the associated biota, such as an astropectinid asteroid.