A Cretaceous carbonate delta drift in the Montagna della Maiella, Italy

The Upper Cretaceous (Campanian\u2013Maastrichtian) bioclastic wedge of the Orfento Formation in the Montagna della Maiella, Italy, is compared to newly discovered contourite drifts in the Maldives. Like the drift deposits in the Maldives, the Orfento Formation fills a channel and builds a Miocene delta-shaped and mounded sedimentary body in the basin that is similar in size to the approximately 350 km 2 large coarse-grained bioclastic Miocene delta drifts in the Maldives. The composition of the bioclastic wedge of the Orfento Formation is also exclusively bioclastic debris sourced from the shallow-water areas and reworked clasts of the Orfento Formation itself. In the near mud-free succession, age-diagnostic fossils are sparse. The depositional textures vary from wackestone to float-rudstone and breccia/conglomerates, but rocks with grainstone and rudstone textures are the most common facies. In the channel, lensoid convex-upward breccias, cross-cutting channelized beds and thick grainstone lobes with abundant scours indicate alternating erosion and deposition from a high-energy current. In the basin, the mounded sedimentary body contains lobes with a divergent progradational geometry. The lobes are built by decametre thick composite megabeds consisting of sigmoidal clinoforms that typically have a channelized topset, a grainy foreset and a fine-grained bottomset with abundant irregular angular clasts. Up to 30 m thick channels filled with intraformational breccias and coarse grainstones pinch out downslope between the megabeds. In the distal portion of the wedge, stacked grainstone beds with foresets and reworked intraclasts document continuous sediment reworking and migration. The bioclastic wedge of the Orfento Formation has been variously interpreted as a succession of sea-level controlled slope deposits, a shoaling shoreface complex, or a carbonate tidal delta. Current-controlled delta drifts in the Maldives, however, offer a new interpretation because of their similarity in architecture and composition. These similarities include: (i) a feeder channel opening into the basin; (ii) an excavation moat at the exit of the channel; (iii) an overall mounded geometry with an apex that is in shallower water depth than the source channel; (iv) progradation of stacked lobes; (v) channels that pinch out in a basinward direction; and (vi) smaller channelized intervals that are arranged in a radial pattern. As a result, the Upper Cretaceous (Campanian\u2013Maastrichtian) bioclastic wedge of the Orfento Formation in the Montagna della Maiella, Italy, is here interpreted as a carbonate delta drift

Palygorskite and eustatism during Mid-Cretaceous in the Maiella Mountain (Abruzzi, Central Italy)

The clay mineralogy of Mid-Cretaceous carbonate pelagic sediments of the Maiella Mountain, a transition zone between the Abruzzi platform and the Umbrian basin, have been studied by X-ray diffraction and transmission electron microscopy. The clay assemblages are composed of chlorite, illite, smectite, illite/smectite mixed-layers and detrital palygorskite. The palygorskite occurs only in sediments deposited during anoxic periods. These periods are associated with sea-level rises, and therefore it is suggested that during Mid-Cretaceous, in the basin of the Maiella Mountain, palygorskite was derived from the reworking of pedogenic crusts or chemical sediments which were deposited on the adjacent platform areas during transgressive events.Deconinck Jean-François, Accarie H. Palygorskite and eustatism during Mid-Cretaceous in the Maiella Mountain (Abruzzi, Central Italy). In: Proceedings of the 9th international Clay Conference, Strasbourg, 1989. Vol IV : Clays in sediments. Diagenesis and hydrothermalism. Strasbourg : Institut de Géologie – Université Louis-Pasteur, 1990. pp. 15-22. (Sciences Géologiques. Mémoire, 88

Palygorskite and eustatism during Mid-Cretaceous in the Maiella Mountain (Abruzzi, Central Italy)

The clay mineralogy of Mid-Cretaceous carbonate pelagic sediments of the Maiella Mountain, a transition zone between the Abruzzi platform and the Umbrian basin, have been studied by X-ray diffraction and transmission electron microscopy. The clay assemblages are composed of chlorite, illite, smectite, illite/smectite mixed-layers and detrital palygorskite. The palygorskite occurs only in sediments deposited during anoxic periods. These periods are associated with sea-level rises, and therefore it is suggested that during Mid-Cretaceous, in the basin of the Maiella Mountain, palygorskite was derived from the reworking of pedogenic crusts or chemical sediments which were deposited on the adjacent platform areas during transgressive events.Deconinck Jean-François, Accarie H. Palygorskite and eustatism during Mid-Cretaceous in the Maiella Mountain (Abruzzi, Central Italy). In: Proceedings of the 9th international Clay Conference, Strasbourg, 1989. Vol IV : Clays in sediments. Diagenesis and hydrothermalism. Strasbourg : Institut de Géologie – Université Louis-Pasteur, 1990. pp. 15-22. (Sciences Géologiques. Mémoire, 88

High Diversity in Cretaceous Ichthyosaurs from Europe Prior to Their Extinction

Background: Ichthyosaurs are reptiles that inhabited the marine realm during most of the Mesozoic. Their Cretaceous representatives have traditionally been considered as the last survivors of a group declining since the Jurassic. Recently, however, an unexpected diversity has been described in Upper Jurassic–Lower Cretaceous deposits, but is widely spread across time and space, giving small clues on the adaptive potential and ecosystem control of the last ichthyosaurs. The famous but little studied English Gault Formation and ‘greensands’ deposits (the Upper Greensand Formation and the Cambridge Greensand Member of the Lower Chalk Formation) offer an unprecedented opportunity to investigate this topic, containing thousands of ichthyosaur remains spanning the Early–Late Cretaceous boundary. Methodology/Principal findings: To assess the diversity of the ichthyosaur assemblage from these sedimentary bodies, we recognized morphotypes within each type of bones. We grouped these morphotypes together, when possible, by using articulated specimens from the same formations and from new localities in the Vocontian Basin (France); a revised taxonomic scheme is proposed. We recognize the following taxa in the ‘greensands’: the platypterygiines ‘Platypterygius’ sp. and Sisteronia seeleyi gen. et sp. nov., indeterminate ophthalmosaurines and the rare incertae sedis Cetarthrosaurus walkeri. The taxonomic diversity of late Albian ichthyosaurs now matches that of older, well-known intervals such as the Toarcian or the Tithonian. Contrasting tooth shapes and wear patterns suggest that these ichthyosaurs colonized three distinct feeding guilds, despite the presence of numerous plesiosaur taxa. Conclusion/Significance: Western Europe was a diversity hot-spot for ichthyosaurs a few million years prior to their final extinction. By contrast, the low diversity in Australia and U.S.A. suggests strong geographical disparities in the diversity pattern of Albian–early Cenomanian ichthyosaurs. This provides a whole new context to investigate the extinction of these successful marine reptiles, at the end of the Cenomanian