Environmental and climatic conditions at a potential Glacial refugial site of tree species near the Southern Alpine glaciers. New insights from multiproxy sedimentary studies at Lago della Costa (Euganean Hills, Northeastern Italy)     

Petra Kaltenrieder  Claudio A. Belis  Simone Hofstetter  Brigitta Ammann  Cesare Ravazzi  Willy Tinner   《Quaternary Science Reviews》2009,28(25-26):2647-2662

It has been hypothesized that refugia of thermophilous tree species were located in Northern Italy very close to the Alps, though, this hypothesis has yet to be tested thoroughly. In contrast to Central and Southern Italy with its relative wealth of data, only a few fragmentary records are currently available from Northern Italy for the last Glacial (Würm, Weichselian). Our new study site Lago della Costa lies adjacent to the catchment of the megafans of the Alpine forelands and the braided rivers of the Northeastern Po Plain that have so far inhibited the recovery of continuous Glacial and Late-Glacial records. We analyze pollen, plant macrofossils, charcoal and ostracods to reconstruct the vegetation, fire and lake history for the period 33,000–16,000 cal. BP. We compare our data with Glacial records from Southern Europe to discuss similarities and dissimilarities between these potential refugial areas. A comparison with independent paleoclimatic proxies allows to assess potential linkages between environmental and climatic variability. New macrofossil and pollen data at Lago della Costa unambiguously document the local persistence of boreal tree taxa such as Larix decidua and Betula tree species around the study site during the last Glacial. The regular occurrence of pollen of temperate trees in the organic lake sediments (fine-detritus calcareous gyttja) suggests that temperate taxa such as Corylus avellana, Quercus deciduous, Tilia, Ulmus, Fraxinus excelsior, Carpinus, Abies alba and Fagus sylvatica, most likely survived the Last Glacial Maximum (LGM) at favorable sites in the Euganean Hills. The percentage values of temperate trees are comparable with those from Southern Europe (e.g. Monticchio in Southern Italy). We conclude that the Euganean Hills were one of the northernmost refugial areas of temperate taxa in Europe. However, the relative and absolute abundances of pollen of temperate trees are highly variable. Pollen-inferred declines of temperate tree communities (e.g. Quercetum mixtum) and low ostracod-inferred water levels at Lago della Costa correspond to the cold Heinrich events H-2 (LGM; 23,000–19,000 cal. BP) and H-3 (around 28,000 cal. BP), as recorded in the marine sediments of the North Atlantic. Similar patterns of significant temperate tree population collapses during cold Heinrich events are recorded at southern Mediterranean sites (e.g. Monticchio and the Alboran Sea). These findings suggest close linkages between Northern Atlantic and South-Central European climates during the past Glacial.  相似文献   

Comment on “Effect of surface wave inversion non-uniqueness on 1D seismic ground response analysis” by Roy et al.     

Alberto Pettiti  Sebastiano Foti  Cesare Comina 《Natural Hazards》2015,75(1):975-981

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Seismic characterization of shallow bedrock sites with multimodal Monte Carlo inversion of surface wave data     

Paolo Bergamo  Cesare Comina  Sebastiano Foti  Margherita Maraschini 《Soil Dynamics and Earthquake Engineering》2011

Sites with a limited overburden over a stiff basement are of particular relevance for seismic site response. The characterization of such stratigraphies by means of surface wave methods poses some difficulties in interpretation. Indeed the presence of sharp seismic contrasts between the sediments and the shallow bedrock is likely to cause a relevance of higher modes in the surface wave apparent dispersion curve, which must be properly taken into account in order to provide reliable results. In this study a Monte Carlo algorithm based on a multimodal misfit function has been used for the inversion of experimental dispersion curves. Case histories related to the characterization of stations of the Italian accelerometric network are reported. Spectral ratios and amplification functions associated to each site are moreover evaluated to provide an independent benchmark test. The results show the robustness of the inversion method in such non-trivial conditions and the possibility of getting an estimate of uncertainty related to solution non-uniqueness.  相似文献   

Two revolutions in the Earth Sciences   总被引：1，自引：0，他引：1  

Cesare Emiliani 《地学学报》1995,7(6):587-597

Two great revolutions have shaken the field of the geological sciences since World War II, one involving the solid Earth and the other involving the ice ages. The former came after a long and gradual preparation that extended across a century. The latter came abruptly, after a long period of stasis during which little conceptually new had emerged. The former did not demolish anything - it was only the logical conclusion of a long process of discovery. The latter demolished a canon that had become a dogma held true for half a century. The reactions of the scientists to the two revolutions are a study in contrast: instant acceptance of the former versus laggard and reluctant acceptance of the latter.  相似文献   

Modelling galaxy spectra in presence of interstellar dust – I. The model of interstellar medium and the library of dusty single stellar populations     

Lorenzo Piovan  Rosaria Tantalo  Cesare Chiosi 《Monthly notices of the Royal Astronomical Society》2006,366(3):923-944

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H ₂ excitation in turbulent interstellar clouds     

Cesare Cecchi-Pestellini  Silvia Casu  Alexander Dalgarno 《Monthly notices of the Royal Astronomical Society》2005,364(4):1309-1314

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Production of metaluminous melt during fluid‐present anatexis: an example from the Maghrebian basement,La Galite Archipelago,central Mediterranean     

S. Ferrero  R. Braga  M. Berkesi  B. Cesare  N. Laridhi Ouazaa 《Journal of Metamorphic Geology》2014,32(2):209-225

Garnet brought to the surface by late Miocene granitoids at La Galite Archipelago (Central Mediterranean, Tunisia) contains abundant primary melt and fluid inclusions. Microstructural observations and mineral chemistry define the host garnet as a peritectic phase produced by biotite incongruent melting at ~800 °C and 0.5 GPa, under fluid‐present conditions. The trapped melt is leucogranitic with an unexpected metaluminous and almost peralkaline character. Fluid inclusions are one phase at room temperature, and contain a CO₂‐dominated fluid, with minor H₂O, N₂ and CH₄. Siderite and an OH‐bearing phase were identified by Raman and IR spectroscopy within every analysed inclusion, and are interpreted as products of a post‐entrapment carbonation/hydration reaction between the fluid and the host during cooling. The fluid present during anatexis is therefore inferred to have been originally richer in both H₂O and CO₂. The production of anatectic melt with a metaluminous signature can be explained as the result of partial melting of relatively Al‐poor protoliths assisted by CO₂‐rich fluids.  相似文献   

Magnetostratigraphic dating of an intensification of glacial activity in the southern Italian Alps during Marine Isotope Stage 22     

Giovanni Muttoni  Cesare Ravazzi  Marzia Breda  Carlo Laj  Alain Mazaud 《Quaternary Research》2007,67(1):161-173

We applied magnetostratigraphy and mammal biostratigraphy to date climate-sensitive pollen cycles and lithostratigraphic units of the Pliocene-Pleistocene Leffe sedimentary succession from the Southern Alps, Italy. The Leffe section was correlated to additional sections (Casnigo, Fornaci di Ranica, and Pianengo) to construct a stratigraphic network along a common fluviatile system (the Serio River) sourced in the Southern Alps and flowing southward into the Po River Basin. We obtained a coherent scenario of climate variability for the last ∼ 2 Myr. At Leffe, lacustrine deposition commenced during the Olduvai Normal Subchron (1.94-1.78 Ma) and lasted up to a chronologic level compatible with Marine Isotope Stage (MIS) 22 (0.87 Ma). Pollen analysis revealed that climate varied cyclically from warm-temperate to cool during this time interval, but never as cold as during glacial intervals. At around MIS 22, climate cooled globally. Gravels, attributed to high-energy braided river systems fed locally by alluvial fans, prograded from the Serio River catchment area over the Leffe Basin and toward the Po Plain in response to a generalized event of vegetation withdrawal and enhanced physical erosion. At this time, Alpine valley glaciers reached their first maximum southward expansion with glacier fronts located at only ∼ 5 km upstream from Leffe.  相似文献   

SIXE: A Payload for MINISAT-02     

Jordi Gómez-Gomar  Jordi Isern  Eduardo Bravo  Franco Giovannelli  Cesare De La Padula 《Astrophysics and Space Science》1998,263(1-4):389-392

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Evidence for Late Carboniferous subduction-type magmatism in mafic-ultramafic cumulates of the SW Tauern window (Eastern Alps)   总被引：1，自引：0，他引：1  

B. Cesare  D. Rubatto  J. Hermann  L. Barzi 《Contributions to Mineralogy and Petrology》2002,142(4):449-464

Hectometric bodies of fresh mafic-ultramafic cumulates have been discovered within the Central Gneiss of the Zillertal massif, SW Tauern window (eastern Alps, Italy). The cumulates, intruded by the Central Gneiss granitoids, are amphibole-bearing harzburgites and norites made of cumulitic olivine (Fo_73-80), spinels, sulphides and plagioclase (An_79-87), included in orthopyroxene (En_76-83) and Ti-pargasite (Mg#=0.73-0.81). Major and trace element geochemistry indicates that these rocks represent olivine + spinel - plagioclase cumulates, in which interstitial melt crystallized as orthopyroxene + Ti-pargasite. The parental melt has trace element patterns typical of subduction zone magmas. The crystallization sequence, mineral compositions, and modes indicate that cumulates formed from a H₂O-rich basaltic andesite, which intruded at low-pressure (~2 kbar) and temperatures of 1,050-1,100 °C. SHRIMP U-Pb dating of zircons from ultramafic cumulates and adjacent metagranodiorite yielded ages of 309LJ and 295Dž Ma, respectively. In agreement with field relationships, these results show that the mafic-ultramafic cumulates represent a co-genetic, early product of the Late Carboniferous plutonic activity in the western Tauern window, which started in the Westphalian, earlier than previously thought. Our data on the most primitive rocks in the Zillertal massif permit, for the first time, insight into the parental magma and thus into the origin of this Late Carboniferous calc-alkaline magmatism, which was most likely related to slab break off during the Late Variscan convergence.  相似文献