Eleonora Regattieri

Duration and dynamics of the best orbital analogue to the present interglacial

Past orbital analogues to the current interglacial, such as Marine Isotope Stage 19c (MIS 19c, ca. 800 ka), can provide reliable reference intervals for evaluating the timing and the duration of the Holocene and factors inherent in its climatic progression. Here we present the first high-resolution paleoclimatic record for MIS 19 anchored to a high-precision 40Ar/39Ar chronology, thus fully independent of any a priori assumptions on the orbital mechanisms underlying the climatic changes. It is based on the oxygen isotope compositions of Italian lake sediments showing orbital- to millennial-scale hydrological variability over the Mediterranean between 810 and 750 ka. Our record indicates that the MIS 19c interglacial lasted 10.8 ± 3.7 k.y., comparable to the time elapsed since the onset of the Holocene, and that the orbital configuration at the time of the following glacial inception was very similar to the present one. By analogy, the current interglacial should be close to its end. However, greenhouse gas concentrations at the time of the MIS 19 glacial inception were significantly lower than those of the late Holocene, suggesting that the current interglacial could have already been prolonged by the progressive increase of the greenhouse gases since 8–6 ka, possibly due to early anthropogenic disturbance of vegetation.

The environmental features of the Monte Corchia cave system (Apuan Alps,central Italy) and their effects on speleothem growth

The Monte Corchia cave system, one of the most famous and popular caves in Italy, has in recent times been the subject of investigation on its speleothems as paleoclimate archives. This paper describes the geology, geomorphology and water chemistry of the cave system with the aim to elucidate the processes that have generated these speleothems and the properties they contain that are so useful for paleoclimatology. Some general conclusions can be drawn: i) the Corchia system is a cave developed over different altitudes during progressive uplift of the mountain chain in which it is located, probably under drainage conditions very different to those of the present. This has allowed the development of a large (ca. 60 km) and deep (-1187 m) karst system; ii) the dewatering phases have left the deepest chambers far away from clastic input and with long drip pathways; iii) the peculiar geological context has permitted the water to intercept and dissolve a significant source of U (still unknown) that facilitates radiometric dating; iv) in the last 1 Ma at least, no significant changes have occurred in the relief and in the epikarst, in the sense that speleothems have grown under very similar conditions. In addition the extremely low Ca concentration of drip waters have permitted low speleothem growth rates and, at least for the “Galleria delle Stalattiti”, the zone under paleoclimate studies,a stable plumbing system (i.e. chemistry and stable isotopes of drip waters) has produced calcite close to isotopic equilibrium.

Wavelet analysis of δ18O and δ13C time-series from an Holocene speleothem record from Corchia Cave (central Italy): insights for the recurrence of dry-wet periods in the Central Mediterraneans

In this work, the continuous wavelet transform (CWT) is used to analyse stable isotope (δ18O and δ13C) time-series from a speleothem from Corchia Cave (Apuan Alps, Tuscany, central Italy). The record spans the ca. 13.3- 0.4 ka period. Both proxies are thought to represent changes in the amount of precipitation and in the hydrological recharge over the cave catchment, and to indicate alternating wetter and drier periods. The CWT shows the presence of different dominant frequency components, changing across the Middle-Holocene. This can be interpreted as mostly related to long term variations in summer and winter insolation, resulting from changes in orbital parameters. The lower frequencies (millennial scale) individuated may have different origin, not always obvious, and are rarely reported in others records. Instead, the short period components (multidecadal to centennial scale) could be in the range of frequencies considered as expression of the solar variability. δ18O and δ13C time-series show very coherent response to lower frequencies, but δ18O time-series show the presence of higher frequencies, that are not reported in the δ13C record. This can be related to a different response of the soil-karst system compared to variability in the δ18O of precipitation and their recharge of the karst. A Matlab® code has been implemented to compute the wavelet transform and to generate all the results presented in this work.

New findings of the Campanian Ignimbrite ash within slope deposits of the Treska valley (former Yugoslav Republic of Macedonia)

In this paper, we describe the first finding of the Campanian Ignimbrite tephra layer in a subaerial succession in the Former Yugoslav Republic of Macedonia. The tephra is interbedded within slope deposits mixed with colluvial loess. The identification of this fundamental stratigraphic marker is based on major elements. The investigated succession is correlated to lacustrine records from Ohrid and Prespa lakes, several archives of the central and eastern Mediterranean, and mainland Ukraine and Russia. Field observations and correlation with lacustrine records (i.e. pollen) indicate that accumulation of the volcanic ash occurred in a dry environment characterized by low vegetation cover and important wind activity, which promoted loess deposition. The recognition of the Campanian Ignimbrite tephra allows the correlation of the loess sediments to the H4 event, as defined in the North Atlantic event climatic stratigraphy.

Environment, Climate and Society in Roman and Byzantine Butrint

A multiproxy analysis (sedimentology, geochemistry and pollen) of sediments recovered in the Butrint lagoon (Albania) allows us to reconstruct the environmental changes that occurred in the area during the 1st millennium AD. In this paper, we compare these analytical results with the evidence provided by archaeological investigations carried out at the site of the Roman city of Butrint (surrounded by these lagoon waters) and in the city’s hinterlands. From this, we can say that different periods of farming and siltation (AD 400–600 and 700–900) were accompanied by increased run-off and wetter conditions in the region. This coincided with the territorial and economic expansion of the Byzantine empire, suggesting the key role of trade in the profound land use changes experienced in Butrint.