Model of bioclastic production for recent stalked crinoids. Application tothe crinoidal limestone of Euville (Oxfordian of Meuse)

Using data on growth rate and life span of modern stalked crinoids, a model for calculating the bioclastic production of pentacrinid meadows is propos ed. An especially important aspect of the model is its treatment of the reg eneration abilities, which can be quite variable and dependent on environme ntal factors. Composition of crinoidal debris (columnals, cirrals, brachial s) is intimately tied to the morphology of the different ecophenotypes. The model predicts that Pentacrinus buchgauensis populations of the Euville cr inoidal limestone (Oxfordian of Meuse) would have generated 362 cm(3).m(-2) .yr(-1) of bioclastic material. At that rate, the entire sedimentary unit c ould have been deposited in 24 000 years. (C) 2000 Academie des sciences / Editions scientifiques et medicales Elsevier SAS.