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41.
Giovanni Monegato Sally E. Lowick Cesare Ravazzi Roberta Banino Marta Donegana Frank Preusser 《第四纪科学杂志》2010,25(5):617-632
The Middle–Late Pleistocene alluvial and lacustrine succession of Valeriano Creek (southeastern Alpine foothills, 190 m a.s.l.) documents the environmental evolution of the piedmont plain before the onset of the Last Glacial Maximum (LGM). The sedimentary record was investigated by multidisciplinary stratigraphical and sedimentological studies coupled with petrographic and palaeobotanical analysis. A chronology has been provided by luminescence, radiocarbon dating and pollen biochronology. The succession developed at the valley mouth of a small catchment and is confined in the piedmont plain by the alluvial fans of major rivers. The oldest deposits were formed during a cold phase during the late Middle Pleistocene. This part of the piedmont plain was generally stable until Termination II, when it was trenched more than 15 m deep by watercourses. The infilling succession of the trench, mostly by low‐energy alluvial sediments interbedded with mire and peat deposits, documents, for the first time on the southern side of the Alps, the relationships between fluvial activity, vegetation and climate change at the foothills piedmont plain during late Marine Isotope Stage (MIS) 5. The stadial–interstadial climate forcing implies a local reorganisation of fluvial dynamics and of forest composition, although substantial plant cover persisted even during cooler stadials. In accordance with coeval alluvial and speleothem records from the northern side of the Alps, this environmental evolution supports a very restricted Alpine glaciation of the main fluvial catchments of the southeastern Alps during MIS 5a–d. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
42.
3D-electrical resistivity tomography monitoring of salt transport in homogeneous and layered soil samples 总被引:1,自引:1,他引:0
Cesare Comina Renato Maria Cosentini Gabriele Della Vecchia Sebastiano Foti Guido Musso 《Acta Geotechnica》2011,6(4):195-203
Monitoring transport of dissolved substances in soil deposits is particularly relevant where safety is concerned, as in the
case of geo-environmental barriers. Geophysical methods are very appealing, since they cover a wide domain, localising possible
preferential flow paths and providing reliable links between geophysical quantities and hydrological variables. This paper
describes a 3D laboratory application of electrical resistivity tomography (ERT) used to monitor solute transport processes.
Dissolution and transport tests on both homogeneous and heterogeneous samples were conducted in an instrumented oedometer
cell. ERT was used to create maps of electrical conductivity of the monitored domain at different time intervals and to estimate
concentration variations within the interstitial fluid. Comparisons with finite element simulations of the transport processes
were performed to check the consistency of the results. Tests confirmed that the technique can monitor salt transport, infer
the hydro-chemical behaviour of heterogeneous geomaterials and evaluate the performances of clay barriers. 相似文献
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Lisa Borgatti Cesare Ravazzi Marta Donegana Alessandro Corsini Mauro Marchetti Mauro Soldati 《第四纪科学杂志》2007,22(2):173-189
The early–middle Holocene lacustrine succession of Corvara in Badia (Italian Dolomites, 1521 m a.s.l.) records landslides and other watershed events before the onset of human pressure. The sensitivity of this archive to relate climate change, watershed processes and vegetation dynamics in the catchment has been explored through a stratigraphic study, including the analysis of sedimentological features, magnetic properties, palaeobotanical records and radiocarbon dating. A palaeolake existed between 10.1 k and 7 k cal. yr BP and was surrounded by a dense conifer forest. Long‐term forest dynamics driven by ecological processes and by climatic conditions favourable to upward forest expansion is recorded throughout the pollen record. Within the fine clastic sedimentation, distinct layers enriched in organic debris of terrestrial origin have been attributed to instant events produced by mass movements. Their age fits the chronology of large landslide events already known in the catchment, enabling correlation of the field evidence of landslides with the lacustrine record. Landslide frequency is controlled by geological and structural factors, but it is significantly modulated by the centennial–millennial climatic phases that characterise the Holocene in the Alps. The taphonomical properties of pollen and macroremains provided valuable insight on the mechanism of watershed processes. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
46.
Cesare Barbieri Carlo Blanco Beatrice Bucciarelli Regina Coluzzi Andrea Di Paola Luciano Lanteri Gian Luca Li Causi Ettore Marilli Piero Massimino Vincenzo Mezzalira Stefano Mottola Roberto Nesci Alessandro Omizzolo Fernando Pedichini Francesca Rampazzi Corinne Rossi Ruggero Stagni Milcho Tsvetkov Roberto Viotti 《Experimental Astronomy》2003,15(1):29-43
There is a widespread interest to digitize the precious information contained in the astronomical plate archives, both for
the preservation of their content and for its fast distribution to all interested researchers in order to achieve their better
scientific exploitation. This paper presents the first results of our large-scale project to digitize the archive of plates
of the Italian Astronomical Observatories and of the Specola Vaticana. Similar systems, composed by commercial flat-bed retro-illuminated
scanners plus dedicated personal computers and acquisition and analysis software, have been installed in all participating
Institutes. Ad-hoc codes have been developed to acquire the data, to test the suitability of the machines to our scientific needs, and to reduce
the digital data in order to extract the astrometric, photometric and spectroscopic content. Two more elements complete the
overall project: the provision of high quality BVRI CCD sequences in selected fields with the Campo Imperatore telescopes,
and the distribution of the digitized information to all interested researchers via the Web. The methods we have derived in
the course of this project have been already applied successfully to plates taken by other Observatories, for instance at
Byurakan and at Hamburg. 相似文献
47.
Cesare Barbieri 《Astrophysics and Space Science》1989,160(1-2):119-122
The Galileo project comprises the design, building, and operation of a 3.5 m Italian telescope the main elements (diameter, mechanical structure, active optics, etc.) of which consist of a duplication of the ESO New Technology Telescope (NTT). Modifications have been introduced in order to allow, beyond thef/11 Nasmyth foci, a prime focusf/2.2 station, a trappedf/6 focus, and a small Cassegrainf/20 facility. Other changes with respect to the NTT have been made to the control and data acquisition system, and to the service building. The telescope could be operational at the end of 1992.Paper presented at the Symposium on the JNLT and Related Engineering Developments, Tokyo, November 29–December 2, 1988. 相似文献
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We carried out a systematic investigation on the pollen content of sediment adhering to skeletal elements of large mammals which originate from the long lacustrine record of Leffe (Early Pleistocene of the Italian Alps). Three local faunas were discovered during mining activities along the intermediate part (spanning from 1.5 to 0.95 Ma) of the basin succession. The excellent pollen preservation allowed testing the reproducibility of the pollen signal from single skeletons. A clear palaeoenvironmental patterning, consistent with the ecological preferences of the considered mammal species, emerged from the canonical correspondence analysis of pollen types diagnostic for vegetation communities. Edaphic factors related to seasonal river activity changes and to the development of swamp forests in the riverbanks are significantly associated to the occurrences of Hippopotamus cf. antiquus, whereas finds of Mammuthus meridionalis belong to fully forested landscapes dominated by conifer or mixed forests of oceanic, warm to cool-temperate climate. Rhinoceros habitats include variable forest cover under different climate states. Distinct cool-temperate, partially open vegetation could be recognized for large deer included Cervalces cf carnutorum.A palynostratigraphic correlation between individual spectra and a reference palynostratigraphic record allowed assignment of many fossil remains to a precise stratigraphic position. This procedure also shown that the Leffe local faunas include specimens accumulated under different environmental and climate states, as a consequence of high-frequency climate changes characterizing the Late Villafranchian Early Pleistocene. 相似文献
50.
The Pleistocene, and possibly also other, older glaciations, are believed to have resulted from a combination of terrestrial and astronomical factors. Preceding glaciation, orogenesis and uplift increased the Earth's albedo and decreased temperature. Lowering of temperature below a certain threshold value permitted the astronomical cause to become operative. While smaller glaciations may have been largely or entirely patterned by the astronomical cause or causes, terrestrial factors had an important effect in determining the course of the larger glaciations. Two time-delay factors are believed to have been responsible for the oscillatory pattern of glaciation: these are plastic iceflow, and crustal warping.Summer insolation variation in the high latitudes is believed to be a more likely astronomical cause than variation of solar radiation. 相似文献