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Geology Institute, ETH-Zürich, CH-8092 Zürich, Switzerland
(e-mail: iwan.s{at}pop.agri.ch)
Cenomanian to mid-Campanian rudist lithosomes, exposed along a transect across the Maiella carbonate platform margin (central Apennines, Italy), are described in terms of faunal and matrix composition, geometry, and facies association. On the external platform, the lithosomes reveal a complex geometry and a comparatively high faunal diversity, whereas lithosomes of the inner platform are generally thinner and show a simple, sheet-like geometry. Based on the abundance of lithosomes and of the associated rudist-derived calcarenites, we propose that lithosome formation and, hence, sediment production preferentially occurred on the outermost platform, although the preservation potential of bioconstructions was low in these high-energy environments. Reworking of rudists led to sediment export both towards more internal areas as well as towards the adjacent basin. In contrast, on the inner platform, rudist lithosome formation was restricted by the lack of an adequate substrate and by higher sedimentation rates.
