Letizia Di Bella

Benthic foraminifera from two coastal lakes of southern Latium (Italy). Preliminary evaluation of environmental quality

Benthic foraminifera and sediment texture were studied on a total of 37 samples, collected from two brackish-water coastal basins: Fogliano Lake and Lungo Lake (central Italy). The research was performed as a preliminary low-cost survey to highlight the degree of the environmental stress and to recognize a possible anthropogenic disturbance. The sedimentological and foraminiferal data were processed by bivariate and multivariate statistical analysis. Three distinct assemblages, referable to different environments were recognized for the Fogliano Lake: inner, intermediate and outer lagoon. Only the outer lagoon assemblage was found in the Lungo Lake. The distribution of foraminifera in the Fogliano Lake suggests a natural environmental stress probably due to the ecological instability typical of marginal environments, while the absence of the inner and intermediate lagoon assemblages in the Lungo Lake suggests an environmental disturbance possibly related to human activities. An interdisciplinary survey including geochemical analyses is recommended in order to deduce the nature and degree of pollution in the Lungo Lake.

Magnetic anisotropy of Plio–Pleistocene sediments from the Adriatic margin of the northern Apennines (Italy): implications for the time–space evolution of the stress field

Abstract The anisotropy of magnetic susceptibility (AMS) of the marine fine-grained Plio–Pleistocene sediments that crop out at the eastern (Adriatic) front of the central–northern Apennines (Italy) indicates a prevalent sedimentary-compactional magnetic fabric with variable overprint of the tectonic strain. The degree of anisotropy and the geometry of the AMS ellipsoids suggest a subdivision of the studied sediments in two distinct ages: Early–middle Pliocene and Late Pliocene–Early Pleistocene. The Early–middle Pliocene sediments show a weak but well defined magnetic lineation parallel to the main fold and thrust axes throughout the region, analogously to the Messinian sediments located in a more internal (western) position of the Apenninic chain. Since the Late Pliocene, the AMS data are not regionally coherent and indicate a reduced and locally variable tectonic influence on the magnetic fabrics. The AMS data have been integrated with the available geophysical information of the present-day stress in the region, with the aim to reconstruct the time–spatial evolution of the stress field in the Adriatic margin of the central-northern Apennines, during the past 5 Ma. The present-day stress field was evaluated using borehole breakout in deep wells (about 50 wells), focal mechanisms of crustal earthquakes (2.5 M d

Benthic foraminiferal assemblages of the imperial harbor of Claudius (Rome): Further paleoenvironmental and geoarcheological evidences

This paper presents a paleoenvironmental reconstruction of historical development in the area of the ancient harbor of Claudius based on micropaleontological and sedimentological data. Benthic foraminifera are reliable tools for this kind of research because they are sensitive to short-time environmental changes induced by both natural and anthropogenic events. By studying eight sediment cores collected from different sections of the harbor, it was possible to reconstruct a comprehensive picture of the harbor complex. Qualitative and quantitative analysis of foraminiferal associations and sedimentological data, along with radiocarbon dating, were useful to identify three key intervals in the history of the coastal area where the harbor developed. The first interval, located at the bottom of all cores, is characterized by a brackish water environment, corresponding to the formation of the first deltaic cusp of the Tiber River. The second interval is characterized by the harbor activities that developed after a general increase in water depth due to a diversion of the Tiber River mouth. The third interval marks the final phase of harbor activities and the subsequent filling of Claudius’ basin. However, a link with the inner Trajanus’ basin was maintained via the central part of the basin, which remained submerged longer, until the early Middle Ages.

Middle-to late-Holocene environmental changes in the Garigliano delta plain (Central Italy): which landscape witnessed the development of the Minturnae Roman colony?

Geomorphologic, stratigraphic, faunistic, palynological and 14C analyses were carried out in the area of the mouth of the Garigliano River characterized by two strand plains that are referred to the Eutyrrhenian and the Holocene, rimming two depressed zones separated by the Garigliano River channel. This study depicts the palaeoenvironmental evolution over the last 8200 years and the landscape context at the time of Minturnae Roman colony. Between 8200 and 7500 yr BP, a wet zone occurred in the northern zone, whereas in the southern part, a lagoon developed. During the final transgression stage and the beginning of the sea level still stand (7500–5500 yr BP), a freshwater marsh formed in the northern zone, and the width of the southern lagoon decreased. Between 5500 and 3000 yr BP, the coastal barrier changed into a delta cusp, a freshwater marsh also appeared in the southern part and the river wandered between the twin marshes. Because of local uplift, previously unknown in this area, part of the floor of the southern marsh emerged, and after 4000 yr BP, both marshes became coastal ponds with prevailing clastic sedimentation. A progressive increment in anthropic forcing on the land took place after 3000 yr BP. The Marica sanctuary was built (7th century BC), and the Roman colony of Minturnae was developed beginning the 3rd century BC. The shallow depth of the ponds prevented their use as harbours, and saltwork plants can be ruled out based on the faunal and palynological data. The ongoing infilling of both ponds was never completed, and their reclamation is still in progress.

Benthic foraminiferal assemblages in active volcanic area of the Azores Islands (North Atlantic Ocean)

The present study shows the preliminary micropalaeontological results obtained from surface samples collected during an Eurofleet marine geological survey in the Terceira offshore (Azores Archipelago, Portugal) carried out in September 2011.Benthic foraminiferal assemblages were studied in order to obtain a sea-floor ecological characterisation in natural stressed environments like active volcanic area of the Azores Islands. Sediments were collected at water depths ranging between 260 and 410 m and consist of blackish, sand-sized glass shards, in which highly vesicularto scoriaceous clasts prevail on fluidal striated fragments. All samples were stained with Rose Bengal to determine living and dead assemblages.The dominance of living specimens suggests that the first generation of foraminiferal colonisers was found. Diversity index (α-Fisher index), Faunal density and Foraminiferal Abnormality Index (FAI) were calculated to assess the structure of the assemblage and the degree of environmental stress. Living and dead assemblages are verysimilar; they are very scarce but sufficiently diversified. The living benthic assemblage is dominated by epi/shallow infaunal species Angulogerina angulosa and typical infaunal taxa like Bolivina spp.Subordinately other epifaunal (Ehrenbergina bradyi, Lenticulina spp., Quinqueloculina seminula, Stomatorbina concentrica) and agglutinated species (Ammoglobigerina globigeriniformis, Eggerelloides scabrus, Haplophragmoides canariensis, Spiroplectinella wrightii, Textularia spp.) are also recorded. Significant frequencies of specimens showing signs of test decalcification were found. These test alterations could be due to hydrothermal fluids, since similar features were recorded in foraminiferal specimens coming from other volcanic substrates in the Aeolian Arc (Tyrrhenian Sea). The dominance of living and dead A. angulosa specimens allows us to consider this species as opportunistic pioneer taxon able to colonise stressed environments. This is confirmed also by the highest values of FAI (>2%), recorded in most of the samples, indicating a persisting environmental stress. Angulogerina angulosa and Bolivina spp. are the species showing more abundant deformed specimens (irregular development of chambers and aberrant tests). On the basis of our observations, the recolonisation process and the spatial distribution patterns are strongly influenced by the sea bottom high hydrodynamic regime which is responsible for volcanic deposit transport and depositional events. These conditions may be reflected on the relationship between benthic foraminifers and substrate features, which are mainly restricted to grain size, morphology and texture of volcanic shards.

Environmental changes by mean the foraminiferal assemblages in the Late Quaternary deposits of Terracina basin (Central Tyrrhenian Sea, Italy).

Micropaleontological analysis, from three cores collected on the Tyrrhenian continental shelf in the Terracina basin allowed to highlight a transgressive trend related to the Holocene sea-level rise (Versilian transgression). Four distinct environments identified by ten benthic foraminiferal assemblages were recognised. The oldest ones is related to lagoon-barrier system or brackish-water environment and is dominated by the euryaline species Ammonia tepida . The progress of transgressive trend have resulted in the replacement of the paleo-lagoon ( Ammonia tepida assemblage) with a sandy beach environment ( Ammonia spp. and Elphidium spp. assemblage), locally interested by vegetated cover (marked by the dominance of epiphytic taxa). Finally the presence of taxa typical of circalittoral zone ( Melonis pompilioides , Reussella spinulosa , Globocassidulina subglobosa , Gavelinopsis praegeri and Asterigerinata adriatica ) marked the sea-level stabilisation and the recent foraminiferal distribution.

Spiculosiphon oceana (Foraminifera) a new bio-indicator of acidic environments related to fluid emissions of the Zannone Hydrothermal Field (central Tyrrhenian Sea)

The new record of a shallow-water submarine hydrothermal field (<150 m w.d.) in the western Mediterranean Sea (Tyrrhenian Sea, Italy) allows us to study CO2 fluid impact on benthic foraminifers. Benthic foraminifers calcification process is sensitive to ocean acidification and to local chemical and physical parameters of seawater and pore water. Thus, foraminifers can record specific environmental conditions related to hydrothermal fluids, but at present their response to such activity is poorly defined. The major outcome of this study is the finding of a very uncommon taxon for the Mediterranean Sea, i.e., the Spiculosiphon oceana, a giant foraminifer agglutinating spicules of sponges. This evidence, along with the strong decrease of calcareous tests in the foraminiferal assemblages associated to hydrothermal activity, provides new insights on the meiofauna living in natural stressed environment. In particular, observations obtained from this study allow us to consider S. oceana a potential tolerant species of high CO2 concentrations (about 2-4 times higher than the normal marine values) and a proxy of acidic environments as well as of recent ocean acidification processes.

Foraminiferal assemblages in active volcanic areas: two study cases from Azores Archipelago (Atlantic Ocean) and Pantelleria Island (Mediterranean Sea)

Lucchi, Renata G. ... et. al.-- 87° Congresso della Societa Geologica Italiana e 90° Congresso della Societa Italiana di Mineralogia e Petrologia, The Future of the Italian Geosciences - The Italian Geosciences of the Future, 10-12 September 2014, Milan, Italy.-- 1 pageThe Montellina Spring (370 m a.s.l.) represents an example of groundwater resource in mountain region. It is a significant source of drinking water located in the right side of the Dora Baltea Valley (Northwestern Italy), SW of Quincinetto town. This spring shows a morphological location along a ridge, 400 m from the Renanchio Torrent in the lower sector of the slope. The spring was investigated using various methodologies as geological survey, supported by photo interpretation, structural reconstruction, NaCl and fluorescent tracer tests, discharge measurements. This multidisciplinary approach, necessary due to the complex geological setting, is required for the importance of the Montellina Spring. It is interesting in the hydrogeological context of Western Alps for its high discharge, relatively constant over time (average 150 l/s), and for its location outside a fluvial incision and suspended about 40 m above the Dora Baltea valley floor (Lasagna et al. 2013). According to the geological setting, the hydrogeological reconstruction of the area suggests that the large amount of groundwater in the basin is essentially favoured by a highly fractured bedrock, covered by wide and thick bodies of glacial and gravitational sediments. The emergence of the water along the slope, in the Montellina Spring, is essentially due to a change of permeability between the deep bedrock and the shallow bedrock and/or surficial sediments. The deep bedrock, showing closed fractures and/or fractures filled by glacial deposits, is slightly permeable. The shallow bedrock, strongly loosened as result of gravitational phenomena, and the local gravitational sediments are, on the contrary, highly permeable. The concentration of water at the spring is due to several reasons. a) The spring is immediately downward a detachment niche, dipping towards the spring, that essentially drains the water connected to the change of permeability in the bedrock. b) It is along an important fracture, that carries a part of the losses of the Renanchio Torrent. c) Finally, it is favored by the visible and buried morphology. Although it is located along a ridge, the spring occurs in a small depression between a moraine and a landslide body. It also can be favored by the likely concave trend of buried base of the landslide. At last, tracer tests of the Renanchio Torrent water with fluorescent tracer are performed, with a continuous monitoring in the Montellina Spring. The surveys permit to verify and quantify the spring and torrent hydrogeological relationship, suggesting that only a small fraction of stream losses feeds the spring.