Alessio Checconi

Biostratigrafia a foraminiferi del Cretaceo Superiore della successione di Parco Priore (Calcare di Altamura, Piattaforma Apula, Italia Meridionale)

This study focuses on the biostratigraphic analysis of an Upper Cretaceous 57 m-thick stratigraphic sedimentary succession outcropping in a quarry at Parco Priore, near the city of Altamura in the Murge (Southern Italy). In the studied area the Upper Cretaceous shallow water carbonate successions represent restricted facies deposited in inner shelf settings within the Apulian Platform (sensu D’Argenio, 1974). During the Mesozoic, the Apulian Platform was one of the peri-adriatic platforms (D’Argenio, 1974) localized along the southern margin of the Tethys. These platforms have been often compared to the presentday Bahamas islands for their general shape, size, subsidence rates as well as their inner platform architecture (Bernoulli, 2001). The studied sedimentary succession, belonging to the Calcare di Altamura formation, is mainly characterised by bedded white-reddish bioclastic, often re-crystallised or dolomitised, mudstones/ wackestones. White-grey calcarenitic and calcisiltitic bedded limestones and thin bedded palaeosoil levels are also present. The micropalaeontological assemblage is dominated by benthic foraminifers (Accordiella conica, Cuneolina pavonia, Moncharmontia apenninica, Minouxia conica, Rotorbinella scarsellai, Dicyclina schlumbergeri, Murgeina apula, Cuneolina spp., Pseudolituonella sp., Aeolisaccus kotori, miliolids, textularids) and dasycladacean algae (mainly Thaumatoporella parvovesiculifera). This benthic association allows to refer the Parco Priore succession to the Coniacian‒lower Campanian time interval. Sedimentological, lithological and micropalaeontological characteristics of the studied succession point to a low-energy inner carbonate platform setting with occasional subaerial exposures. [Upper Cretaceous benthic foraminiferal biostratigraphy of Parco Priore (Calcare di Altamura formation, Apulian Platform, southern Italy)]

TAPHONOMIC ASPECTS OF THE MIOCENE ICHNOFOSSIL-LAGERSTÄTTE FROM CALCARENITE TURBIDITIC BEDS IN THE VERGHERETO MARLS (NORTHERN APENNINES, ITALY)

Five, 3-8 cm-thick calcarenitic turbiditic beds belonging to overbank deposits in the marginal sector of Marnoso-arenacea Basin, close to the intrabasinal high of Verghereto (Romagna, Northern Apennines, Upper Miocene), exhibit a well preserved ichnofossil-lagerstatte. The lagerstatte is composed by 43 ichnotaxa: 31 of them are preserved as casts at the sole of turbidites (background hypichnia) (group a), while 12 of them occur at the top (post-turbidite epichnia) and within (endichnia) (group b). The ichnodensity reaches its maximum at the top of the turbiditic beds. Background hypichnia (group a) is represented by graphoglyptids and non-graphoglyptid resting traces (background ichnofauna), with three-dimensional networks and shafts, meander systems, radiate, plug-shaped or stellatae structures forming clusters and unbranched systems of strings. Many taphonomic features suggest a fluting induced by bottom currents; graphoglyptids should have colonised the substrate after the action of these currents being not destroyed or fluted. All hypichnial structures are perfectly preserved by the turbidite casting and in this phase also endichnial burrows could develop. Post-turbidite epichnia (group b) concern vagile feeding burrows that developed horizontal patterns in a post-turbiditic regime, during the suspension phase of fine material; they were probably produced by organisms transported by suspension flows. Here, the very high ichnodensity suggests a competition among burrowers under stable currents with occurrence of vagile opportunistic organisms immediately followed by others that produced radiate spreite structures. SHORT NOTE

PETROGRAPHIC ANALYSIS OF TRACE FOSSIL DESMOGRAPTON FUCHS, 1895 FROM THE MIOCENE OF NORTHERN APENNINES (ITALY): A METHODOLOGY TO DETECT HYPICHNIAL FEATURES AND IMPLICATIONS ON THE GRAPHOGLYPTID ETHOLOGY

The trace fossil Desmograpton Fuchs, 1895, as many other graphoglyptids, has been considered to be a typical pre-turbidite, three-dimensional burrow system formed in mud and preserved as a casting at the sole of turbidites. This classic interpretation was mostly based on hypichnial preservation, due to the lack of direct evidence (e.g. modern seafloor pictures) for pre-depositional or post-depositional origin. Due to the accidental series of processes invoked to explain the perfect hypichnial preservation of this delicate trace fossil, several doubts and questions have been raised. To try to clarify the sedimentary processed that lead this trace fossil to be preserved, 26 thin sections of Desmograpton dertonensis Sacco, 1888 and Desmograpton ichthyforme Macsotay, 1967 have been performed at sand/clay interface of thin-bedded sandstone turbidites in the Miocene marl deposits of Verghereto, Northern Apennines (Italy). Petrographic analysis of textures and grains of the burrow-filling sediments points out that most of the grains of burrows differ from those of overlying sand, being either more or less sorted and differ in composition and locally also in grain size. Burrows are occasionally characterised by an upper rim, more or less thick, enriched in glauconite, phosphates, pyrite or quartz. Axial cuts of the strings show that rim was involved in diagenetic compaction, squeezing and fluid migration modifying the original shape of the trace fossil. In pre-depositional conditions the oblique-oriented filling is the only explication to preserve the upper rim of original mud, while compaction produced asymmetry in hypichnial tunnels. This petrographic approach, performed for the first time on this graphoglyptid genus, also elucidates the complex interaction of several taphonomic processes that led to the preservation of Desmograpton . The application of a similar petrographic approach to other graphoglyptids could help to better understand their origin, ethology and their preservation processes.

GLOMOMIDIELLA N. GEN. (FORAMINIFERA, MILIOLATA, NEODISCIDAE): A NEW GENUS FROM THE LATE GUADALUPIAN-LOPINGIAN OF HYDRA ISLAND (GREECE)

A new genus of Foraminifera (Miliolata, Cornuspiroidea, Neodiscidae) is erected from the late Guadalupian (Capitanian = Midian) to Lopingian sedimentary succession of the island of Hydra (Greece). It represents an important phylogenetic form, probably at the origin of several genera (or subfamilies of the authors) that became relatively widespread during the Lopingian (Late Permian). Glomomidiella n. gen. is characterized by an entirely glomospiral coiling and rudimentary pseudoseptation.

Lower Miocene coralline red algal assemblages from Southern Apennines (Cusano Formation, Matese Mountains, Italy)

Lower Miocene carbonate sediments, known as “Calcari a Briozoi e Lithothamni” (Bryozoans and Lithothamnium Limestones BLL), outcrop in Southern Apennines (Selli, 1957; Barbera et al., 1978). In the eastern Matese Mountains BLL overlay Mesozoic shallow water sediments with a paraconformity and grade upward into Serravallian limestones (“Orbulina marls”) through a phosphatic level. The BLL formation does not show stratification and generally consists of thick massive banks with calcarenitic or ruditic texture. Fossil assemblage is mainly constituted by red algae (Rhodophyta, Corallinales) and bryozoans, and secondarily by bivalves (ostreids and pectinids), benthic foraminifera, balanids, serpulids, and echinoids. Planktonic foraminifera are rare and increase in abundance near the boundary with the overlying “Orbulina Marls”. These BLL deposits can be ascribed to the rhodalgal lithofacies of Carannante et al. (1988). This study focuses on BLL outcrops located in the southern part of Matese Mountains. In this area, these carbonate sediments rich in corallines and bryozoans are known as “Cusano Formation” (Selli, 1957). This formation is characterized by massive carbonate banks consisting of rhodolith floatstones-rudstones. They show some local differences in thickness, texture assemblage, grains composition and packing. Rare algal bindstones are also locally present (Carannante & Simone, 1996). Although miogypsinids have been commonly observed in BLL Formation (e.g. Schiavinotto, 1985), in the Matese Group they are only locally present (Carannante & Simone, 1996). However the occurrence of Pecten pseudobeudanti may support a Burdigalian age for the basal interval of the Cusano Formation (Carannante & Simone, 1996). The study area is characterised by palaeo-channels located in the lower part of a Lower Miocene open carbonate shelf (Carannate, 1982). Some authors (Simone & Carannante, 1985; Carannante & Simone, 1996) proposed an analogy between the detritic sediments of Cusano Formation and the “Détritique Côtier” biocenosis sediments (Pérès & Picard, 1964) that characterize some modern circalittoral Mediterranean environments. The aim of this study is to define the coralline assemblages of the Cusano Formation in order to assess the palaeoenvironmental evolution of this open carbonate shelf within the paleogeographical evolution of the Matese Group Area. Eleven sections, outcropping in Pietraroia, Cusano Mutri and Ponte Arcicchiaro, have been investigated in term of biogenic components, coralline taxonomic assemblages, coralline growth-forms and related taphonomic signatures.