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  • 1
    Publication Date: 2021-06-16
    Description: During the Quaternary several glaciations occurred in the mountain regions around the Mediterranean and, in recent years, new ages have better constrained their timing. However, this is not the case for the Apuan Alps, a high-rainfall mountain chain adjacent to the Mediterranean Sea. Here, in spite of the widespread evidence for glaciers, the complete lack of geochronological information hinders our understanding of glaciation history. In this paper, we utilize speleothem ages to better constrain the timing of these glacial features. We re-examine 293 uranium‑thorium ages from 19 speleothems collected in five caves at different elevations. After a period of very low growth between 160 and 132 ka, the analysed speleothems grew almost continuously to ~75 ka, this period was followed by intermittent growth with lower deposition rate and presence of hiatuses until ~12.5/12 ka. This is consistent with an ice coverage persisting over the Apuan Alps, inhibiting or interrupting the growth of speleothems via the limited availability of groundwater and the scarcity/absence of soils. This interval is much greater than the time interval that has previously been attributed to the existence of glaciers on the Apuan Alps, which has been assumed to be restricted to Marine Isotope Stage (MIS) 2. Instead, ice cover probably also appeared in the Apuan Alps during MIS 4. The phase of restarting of growth, which may implies the definitive or substantial glacier melts seem to predate the Holocene
    Description: ARCA project “Arctic: present climatic change and past extreme events” founded by the Italian Ministry of Education, Universities and Research (MIUR); Australian Research Council Discovery Projects grant DP110102185; Palaeoclimatic palaeoenvironmental evolution of the Apuan area since the Last Glacial Maximum, Pisa University; Clima ed eventi alluvionali estremi in Versilia: integrazione di nuove tecniche geoarcheologiche, geomorfologiche, geochimiche e simulazioni numeriche, Fondazione Cassa di Risparmio di Lucca Call 2016
    Description: Published
    Description: 62-71
    Description: 5A. Paleoclima e ricerche polari
    Description: JCR Journal
    Keywords: speleothem ; glacier ; Apuan Alps ; MIS2 ; MIS3 ; MIS4 ; Paleoclima
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2021-06-16
    Description: High-resolution isotopic analyses were performed on RL4 flowstone from Renella Cave (Alpi Apuane, central Italy), a speleothem studied previously at low resolution. The new data are discussed together with recently obtained data from Corchia and other localities in the central Mediterranean, to elucidate the possible origin and regional articulation of a climatic event centred at ca. 4.0 ka. This analyses indicates that central to southern Italy between ca 3.8 and 4.3 ka was characterized by drier conditions, whereas in Northern Italy the event seems less expressed or, as within the Alps, marked by cooler and wetter conditions. Several lines of evidence suggest that this event could be characterized by longer summer drought and possibly by little impact on precipitation during winter, even if this aspect needs to be explored in more detail. However, the event is particularly prominent in the northern sector of the African Monsoon domain, which has been robustly linked to southward shifts in the ITCZ; whereas its occurrence is uncertain on northern European latitudes. However, many proxies indicate that there aridification probably started some centuries earlier and culminated at ca. 4.0 ka. Taken as a whole, these data can be used to clarify the regional articulation of this event, but interpretations based on general circulation are still elusive.
    Description: Published
    Description: 5-17
    Description: 5A. Paleoclima e ricerche polari
    Description: N/A or not JCR
    Keywords: 4.2 event ; speleothem ; Mediterranean ; Renella Cave
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
    Publication Date: 2018-03-30
    Description: 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.
    Description: Published
    Description: 128-137
    Description: 5A. Paleoclima e ricerche polari
    Description: JCR Journal
    Keywords: continuous wavelet transform analyses ; speleothem ; stable isotopes ; Holocene
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
    Publication Date: 2019-01-29
    Description: We present new data on the 4.2 ka event in the central Mediterranean from Corchia Cave (Tuscany, central Italy) stalagmite CC27. The stalagmite was analyzed for stable isotopes (delta13C and delta18O) and trace elements (Mg, U, P, Y), with all proxies showing a coherent phase of reduced cave recharge between ca. 4.5 and 4.1 ka BP. Based on the current climatological data on cyclogenesis, the reduction in cave recharge is considered to be associated with the weakening of the cyclone center located in the Gulf of Genoa in response to reduced advection of air masses from the Atlantic during winter. These conditions, which closely resemble a positive North Atlantic Oscillation (NAO) type of configuration, are associated with cooler and wetter summers with reduced sea warming, which reduced the western Mediterranean evaporation during autumn–early winter, further reducing precipitation.
    Description: ARCA project “Arctic: present climatic change and past extreme events” funded by the Italian Ministry of Education Universities and Research (MIUR); Australian Research Council Discovery Project DP160102969; Climate and alluvial event in Versilia: integration of Geoarcheological, Geomorphological, Geochemical data and numerical simulations Fondazione Cassa di Risparmio di Lucca; PRA-2018-41 Georisorse e Ambiente” funded by the University of Pisa
    Description: Published
    Description: 135-151
    Description: 5A. Paleoclima e ricerche polari
    Description: JCR Journal
    Keywords: speleothem ; 4.2 ka BP event ; isotopes ; trace elements ; Paleoclima
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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