Ilaria Mazzini

Paleoenvironmental Reconstruction of Marginal Marine Environments From Combined Paleoecological and Geochemical Analyses on Ostracods

Marginal marine environments are complex systems, which show physico-chemical instability due to seawater/fresh water interactions. During the Quaternary these features have been more complicated by the global climatic and sea level variations. Consequently, the use of ostracod shell chemistry (trace elements, δ 13 C, δ 18 O and 87 Sr/ 86 Sr) to decode the paleohydrochemical characters often is not enough to understand the paleoenvironmental changes. But, if geochemistry is coupled with the classic taxonomical/paleoecological analyses, it may provide a more unambiguous reconstruction. Combined geochemical and paleoecological analyses on ostracods were applied to two boreholes drilled in Quaternary sequences in central Italy. At Migliara (Latium), the inferred salinity deduced from ecology and geochemical data on Cyprideis shells suggests a simple mixing between marine and fresh water, mainly caused by sea-level oscillations. The lack of correlation between ostracod ecology and geochemical data in the Albinia core (Tuscany) can be explained by the mixing of waters from at least three different sources.

Palaeoenvironmental analysis of Early Pleistocene brackish marshes in the Rieti and Tiberino intrapenninic basins (Latium and Umbria, Italy) using ostracods (Crustacea)

Abstract Recent palaeontological and sedimentological studies on the Upper Pliocene–Lower Pleistocene continental deposits of the Rieti and Tiberino basins (Latium and Umbria, Italy) showed the existence of brackish marshes influenced by the Early Pleistocene Tyrrhenian sea. The micropaleontological analyses carried out on five sections cropping out in the northern sector of the Rieti Basin and on one section cropping out in the southwestern branch of the Tiberino Basin showed the repeated alternance of two ostracod assemblages. The first is characterized by a very abundant ostracod association dominated by Cyprideis torosa , typical of brackish waters; the second one is less rich in specimens and dominated by several species of freshwater Candoninae. This alternance allowed the recognition of several changes in the water salinity that could be related to many Early Pleistocene sea-level changes. Palaeosalinities were estimated for both the Tiberino and the Rieti Basin using the morphological analysis of the shell of Cyprideis torosa (ornamentation, nodosities and percentages of sieve-type pore canals). The obtained palaeosalinity values, ranging from freshwater to oligohaline, show slightly higher salinities for the Tiberino Basin, located nearer the ancient coastline, than for the Rieti Basin.

Vegetation, climate and environmental history of the last 4500 years at lake Shkodra (Albania/Montenegro):

Three parallel overlapping cores have been taken in the Albanian side of Lake Shkodra (Albania/Montenegro). The chronological frame of the record, spanning approximately the last 4500 years, has been assessed using four radiocarbon dates and four well-known tephra layers of Italian volcanoes. Multidisciplinary analyses turned out to be decisive to understand environmental, climatic changes and human impact. Here, we focus on palynology. The humidity at Shkodra was always enough to allow the developing of a luxuriant arboreal vegetation. The pollen percentage diagram does not record important changes in terrestrial plants percentages. Arboreal pollen (AP) shows only a rather slight decrease, with ‘natural forests’ replaced by intensive cultivation of chestnut and walnut in the last seven/eight centuries. The rather minimal changes in composition and dominance are because of the fact that the pollen rain comes from different vegetation belts, from the Mediterranean to the alpine one. Two major periods of humidity are found, one at the base of the pollen concentration and influx diagram, before 4100 yr BP, the other at 1300 yr BP. Minima in pollen influx and concentration occurred soon before 4000, at ca. 2900 and at ca. 1450 yr BP These minima, interpreted as aridity crises, show a temporal coincidence with the so-called Bond events 1-3 already found in other central and eastern Mediterranean records. The minimum in AP occurring after 500 yr BP could represent the record of the ‘Little Ice Age’, even if it could be the effect of a strong land use.

Palynology and ostracodology at the Roman port of ancient Ostia (Rome, Italy)

New detailed palynological and ostracodological analyses together with texture data from a sediment core drilled in Ostia Antica confirm the existence of the ancient Ostia harbour and its location by the Tiber River. Using the different proxies analysed in this work and chronologically framing the sediment record with three AMS radiocarbon dates, four phases have been singled out: pre-harbour, harbour bay under fluvial influence, more protected harbour basin and post-harbour phase. Ostracodology is used to reconstruct the marine versus freshwater influence in the basin. Palynology is used to reconstruct the plant landscape and the surrounding environment. Phases with low pollen concentration and expansions of NPPs suggest soil erosion and are alternated with quieter ones, where human impact was very clear. Deciduous oaks typical of coastal plain forests are the main taxon during the harbour phases. The occurrence of riparian trees increases in periods with low pollen concentration, high NPPs and very high pine percentages. These should be the periods in which important sediment inputs inside the harbour basin arrived and could be the expression of intense flooding phases. The comparison between the ostracod assemblages recovered in the two cores and has led to speculate a complex harbour structure. A separation could explain the micropalaeontological differences between the cores. Thus, we suggest that a pier must have been built in order to protect the inner harbour from the marine influence and to unload the goods transported by the big ships.

Geochemical and Palaeoecological Analyses of Mid Pleistocene to Holocene Ostracod Assemblages from Valle di Castiglione (Italy): Palaeoenvironmental and Palaeoclimatic Assessment

Abstract Sediments from Valle di Castiglione in Italy provide a reference sequence for Middle Pleistocene to Holocene palaeoclimate reconstruction of the Mediterranean area. Stable isotope and trace element signals from ostracod valves, as well as palaeoenvironmental analyses (autoecology, community analysis and mutual ostracod temperature range), provided results that cannot be correlated with those derived from pollen and other proxy records. The lack of correlation is attributed to the peculiar geological, hydrogeological and hydrochemical setting of the Valle di Castiglione maar lake. The main trigger for the hydrochemical changes in the waterbody and, therefore, in the ostracod isotopic and trace element signatures, is likely the volcano-tectonic activity in the area. This illustrates how ostracod trace element and isotopic analyses are not the most appropriate tools for palaeoclimate reconstructions from lakes with complex hydrological features, such as some crater lakes, and demonstrates the need for care in selecting lacustrine sequences for such studies.

Occurrence of fossil and recent Microceratina Swanson 1980 (Ostracoda, Eucytherurinae) in the Mediterranean

The systematics and distribution of Microceratina Swanson 1980 are studied. Five species have been referred to this genus: Microceratina quadrata Swanson 1980 (type species), Microceratina foveolata (Colalongo and Pasini 1980) nov. comb., Microceratina poligonia (Colalongo and Pasini 1980), Microceratina pseudoamfibola (Barbeito-Gonzalez 1971) nov. comb. and Microceratina reticulata (Bonaduce, Ciampo and Masoli 1975). With the exceptions of the type species, which have been found in littoral sediments in Southern New Zealand and Southeastern Australia, and of M. poligonia, recovered in two sites of the North Atlantic, the genus Microceratina seems to be mainly distributed in the Mediterranean area, from the Tortonian to Recent.

Mixtacandona talianae n. sp. (Crustacea, Ostracoda) from the Holocene of Grotta del Lago (Umbria, central Italy)

Mixtacandona talianae n. sp. (Ostracoda, Candoninae), collected in the Holocene filling sedimentary succession of the Grotta del Lago near Triponzo (Umbria, Central Italy), is described and illustred. This medium-small sized species is characterized by a remarkable dorsal protuberance on the left valve. 14C radiometric ages on the sediments correlatable with those bearing the new species have provided ages of 4,527-4,409 y BP (calibrated ages).