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Ichnocoenoses in the Oligocene to Miocene foredeep basins (Northern Apennines, central Italy) and their relation to turbidite deposition

Monaco P., Checconi A., Milighetti M.

Acta Geologica Polonica

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2010

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Vol. 60, no. 1

53-70

EN

Analysis of trace fossil abundance and diversity in the Oligocene to Miocene foredeep and piggyback basins of the Tuscan-Romagna-Umbrian Apennines allows us to recognize five ichnocoenoses. The deposits reflect sedimentary environments from slope to basin plain, whose sedimentation was directly controlled by synsedimentary tectonics: attached fan lobes and channels, lobe- and channel-fringes, overbank-fringes of intrabasinal highs, distal detached lobes of basin plain and slope-proximal interfans. The graphoglyptid: non-graphoglyptid ratio has been considered as the chief factor in the study of ichnologic material from Falterona-Cervarola-Trasimeno, Marnosoarenacea and Marne di Vicchio-Verghereto stratigraphic units. The study shows that there is an increase in ichnodiversity and ichnodensity of graphoglyptids, which are typical mainly in detached lobes of basin plain and overbank-levee deposits whose background ichnofauna also shows better preservation.

2

DMT-Predicted vs observed settlements: a review of the available experience.

Monaco P., Totani G., Calabrese M.

Studia Geotechnica et Mechanica

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2007

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Vol. 29, nr 1-2

103-120

EN

This paper presents a compilation of documented case histories including comparisons of DMT-predicted vs observed settlements, in order to review the available experience in the use of DMT for settlement calculations and to evaluate the accuracy of settlement predictions based on DMT. The available data indicate that, in general, the constrained modulus obtained by DMT (MDM-i) can be considered a reasonable "operative modulus" (relevant to foundations under "working conditions") for settlement predictions based on the traditional linear elasticity approach. Attention is also given to the determination of the strain range appropriate to MDMT, in view of the possible use of MDMT for settlement predictions based on non-linear methods taking into account the decay of soil stiffness with strain level.

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Functional morphology and ethology gathered by Thalassinoides branched burrows in Mesozoic shallow water environments

Monaco P., Giannetti A.

Volumina Jurassica

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2006

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Vol. 4, no. 1

99-100

EN

Each part of a crustacean burrow has an important and specific function within the ecology and trophism of the burrower. It goes from the oxygenation and irrigation of tunnels to the protection of the organism and the storing of organic material for feeding (also predation, e.g. carnivorous crustaceans such as stomatopods). Considering modern thalassinoidean burrows (Thalassinoides), the most important characteristics are the presence of surficial mounds, vertical shafts, tunnels and horizontal galleries, turning chambers, organic debris within burrows, Y-or U-shaped burrows and the number and type of apertures on the seafloor. Analysis of the Pliensbachian, lagoonal deposits of the Calcari Grigi Formation (Trento Carbonate Platform, Southern Alps, Italy) and of the Albian outer shelf deposits of the Sacaras Formation (Serra Gelada, Southeastern Spain) gave rise to individuate different specimens of Thalassinoides suevicus trace fossils. They are well preserved in three-dimensions and therefore are useful to gather the trophism of the ancient burrowers in shallow-water environments. These Y-shaped, branched traces were studied observing and measuring diameter of tunnels, enlargement at the bifurcation point, development of the vertical burrow and coarse-grained skeletal debris infilling. Within the studied sections, abundance and dimensions of trace fossils vary, developing repetitive "burrow-decreasing upward" parasequences (BDUP), 2.3-2.9 m thick (Giannetti & Monaco 2004). They represents a useful record of functional morphology of crustacean decapods in shelf environments. We have hypothesized that the regular mazes of Mesozoic crustaceans were mainly developed on horizontal planes (commonly few centimetres inside the substratum), while vertical shaft were rudimentary or lacking, differing from those largely developed by modern crustaceans. The presence of tubular tempestites proves the existence of apertures on the seafloor, even if only the horizontal part of the filled burrows is generally preserved. According to the scheme proposed by Nickell & Atkinson (1995), we observe that the main function of Thalassinoides was the nutritional strategies through the sediment processing and storage of material for maintenance purposes. The sediment processing was supported by the storage of nutritional material (chambered burrows filled by organic detritus). The composition of organic detritus varies from coarse-grained to fine-grained crashed bioclasts, indicative either of biogenic sorting or of the storage of debris coming from the seafloor and fallen down into the burrow. The concentration of coarse-grained fragmented shells close to other free tunnels was probably due to the motion strategy of the crustaceans, as in actual cases. Proofs of irrigation of burrows and entrance from the seafloor are rare and can be deduced from few findings, closely similar to the burrows of modern crustaceans. In the category of the vertical elements, we have considered inhalant and exhalant shafts, but these vertical elements are rare and poorly developed. Anyway, they indicate the presence of suspension feeders (whose primary nutritional source is the water column) and of deposit feeders. According the scheme proposed by Nickell and Atkinson, all the studied Thalassinoides testify the presence of organisms belonging to the category of the deposit feeders (looking for food within the substratum) and to that of the omnivorous scavengers, which eat organic debris present on the seafloor and deriving from algae and other animals.