Maria Gabriella Carboni

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.

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.

BIO- AND MAGNETO-STRATIGRAPHY IN THE TIBER VALLEY REVISED

Abstract The stratigraphy of three sections of marine deposits in the Tiber valley, north of Rome, was investigated in detail. Biostratigraphic investigation covered the Valle Ricca (Tini quarry), Fosso Liano and Lugnano sections. The Valle Ricca and Lugnano sections show continuity in sedimentation from the latest Pliocene to Early Pleistocene. In the Fosso Liano section Upper Pliocene sediments are missing, as in other outcrops in central Italy, and the Lower Pleistocene deposits lie unconformably on the Middle Pliocene ones. Possible causes of these features are discussed. Magnetostratigraphy and rock magnetism analyses were performed only in the Valle Ricca section. The data shows that the previously recognised reversal around a volcanic level is the effect of strong changes in the magnetic mineralogy and it is not representative of true geomagnetic changes.