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Exploring the potential of tree-ring chronologies from the Trafoi Valley (Central Italian Alps) to reconstruct glacier mass balance 总被引:2,自引:0,他引:2
GIOVANNI LEONELLI MANUELA PELFINI PAOLO CHERUBINI 《Boreas: An International Journal of Quaternary Research》2008,37(1):169-178
Two tree-ring chronologies of stone pine ( Pinus cembra L.) and two of Norway spruce ( Picea abies Karst.) were constructed on the basis of data from three high-altitude sites in the Trafoi Valley (Central Alps, Italy) to test tree species sensitivity to climate at different sites and to explore the potential of the two species for reconstructing the mass balance of two glaciers in the same region (the Careser and Hintereis glaciers). Influence of climate on tree-ring growth and on glacier mass variations was tested by means of Pearson's correlation and response functions. At highest altitude sites, both species appeared to be sensitive to July temperatures, while stone pine also showed higher sensitivity than Norway spruce to previous winter precipitation. Comparing the dendrochronological and glaciological series, stone pine showed higher negative correlations with glacier mass balance series than Norway spruce. These different relationships reflect different species responses to climate, and stone pine is potentially useful in reconstructing past glacier mass balance in the Central Alps. Extreme climatic events induce different and even contrasting responses of tree-ring growth and glacier mass variations and may therefore bias tree-ring-based glacier mass balance reconstructions. 相似文献
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A remote sensing based approach to determine forest fire cycle: case study of the Yenisei Ridge dark taiga 总被引:1,自引:0,他引:1
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ABSTRACT Standard hydrological methods have been used to evaluate the water balance of a Central American river basin located in Costa Rica, for the purpose of appraising its water resources potential. Estimates are made of the present utilization of water by each major sectorial user, and a comparison of demand and supply is presented that enables the determination of the degree of present utilisation of water resources. 相似文献
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PAOLO GIACCARIA 《Geographical review》2012,102(3):293-315
The existing postcolonial literature privileges the British and French imperial/colonial history that mirrors the ongoing debate on the relationship among cosmopolitanism, universalism, and imperialism. These debates take for granted the Kantian and Hegelian hierarchy of European civilizations, hence marginalizing the southern shores of Europe and the broader Mediterranean space. Drawing on Mignolo's notion of “border thinking” and on Isin's account of the city as a “difference machine,” I address the issue of how imperialism, colonialism, and cosmopolitanism come together and relate to each other in the context of the Mediterranean (allegedly) cosmopolitan cities. In particular, cosmopolitanism is read as the outcome of the reciprocal adjustment of interior and exterior borders in the making of modernity/coloniality in the Mediterranean. Focusing on the Ottoman millet system, my main claim in this article is that cosmopolitanism worked as a peculiar dispositif within the urban difference machine, enabling the city to sustain the tension between different accounts of citizenship. 相似文献
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Exposure age dating and Equilibrium Line Altitude reconstruction of an Egesen moraine in the Maritime Alps, Italy 总被引:1,自引:0,他引:1
PAOLO ROBERTO FEDERICI DARRYL E. GRANGER MARTA PAPPALARDO ADRIANO RIBOLINI MATTEO SPAGNOLO ANDREW J. CYR 《Boreas: An International Journal of Quaternary Research》2008,37(2):245-253
Four boulder samples from the Piano del Praiet frontal moraine in the Gesso della Barra Valley (Maritime Alps) have been 10 Be dated. The results give a weighted mean age of 11 340±370 (870) yr, constraining the frontal moraine to the Egesen glacial stadial, during the Younger Dryas cold phase. By applying the same 10 Be production rate to other Egesen moraines previously dated in the Alps, we obtain similar ages for all of them. This suggests a synchroneity of the Egesen deglaciation in the European Alps at the end of the Younger Dryas. From the palaeoshape of the Egesen glacier, reconstructed by means of geomorphological mapping, an Equilibrium Line Altitude depression (δELA) of −520 to −530 m, with respect to the present-day ELA, and of −260 to −320 m, with respect to the Little Ice Age ELA, has been calculated. Comparison with other Alpine sector δELAs indicates that the Maritime Alps experienced humid climatic conditions during the Younger Dryas. 相似文献
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Compositional Layering and Syn-eruptive Mixing of a Periodically Refilled Shallow Magma Chamber: the AD 79 Plinian Eruption of Vesuvius 总被引:4,自引:1,他引:3
CIONI RAFFAELLO; CIVETTA LUCIA; MARIANELLI PAOLA; METRICH NICOLE; SANTACROCE ROBERTO; SBRANA ALESSANDRO 《Journal of Petrology》1995,36(3):739-776
A detailed study of the pyroclastic deposits of the AD 79 PompeiPlinian eruption of Vesuvius has allowed: (1) reconstructionof the thermal, compositional and isotopic (87Sr/86Sr) pre-eruptivelayering of the shallow magma chamber; (2) quantitative definitionof the syn-eruptive mixing between the different magmas occupyingthe chamber, and its relationships with eruption dynamics; (3)recognition of the variability of mafic magma batches supplyingthe chamber. During the different phases of the eruption 2530%of the magma was ejected as white K-phonolitic pumice, and 7075%as grey K-tephri-phonolitic pumice. The white pumice resultsfrom the tapping of progressively deeper magma from a body (T= 850900%C) consisting of two distinct layers mainlyformed by crystal fractionation. The grey pumice results fromsyn-eruptive mixing involving three main end-members: the phonoliticwhite magmas (salic end-member, SEM), mafic cumulates(cumulate end-member, CEM) and a crystal-poor greyphono-tephritic magma (mafic end-member, MEM), which was nevererupted without first being mixed with white magma.Evidence is provided that mixing occurred within the chamberand was characterized by a transition with time from physicalmixing at a microscopic scale to chemical hybridization. TheMEM magma had a homogeneous composition and constant 87Sr86Srisotopic ratio, possibly as a result of sustained convection.No unambiguous liquidus phases were found, suggesting that theMEM magma was superheated (T = 10001100C); its verylow viscosity was a main cause in the establishment of a physicaldiscontinuity separating the white and the grey magmas. Thewhite-grey boundary layer possibly consisted of a multiply diffusiveinterface, periodically broken and recreated, supplying thephonolitic body through mixing of moderate amounts of fractionatedgrey melts with the overlying white magma. The presence of alarge overheated mass indicates the young, growing stage ofthe AD 79 chamber, whose main engine was the periodic arrivalof hot mafic magma batches. These were characterized by K-tephriticto K-basanitic compositions, high temperatures (>1150C),high volatile contents (2025% H2O +Cl+F+S), low viscosities[(1+2 102 poises)] and relatively low densities (25002600kg/m3). The birth of the Pompei chamber followed the repeatedarrival of these batches (on average characterized by 87Sr/86Sr070729)into a reservoir containing a tephriticphonolitic, crystal-enriched,magma, a residue from the preceding Avellino Plinianeruption (3400 BP).In fact, about half of magma ejected duringthe AD 79 eruption could have been inherited from pre-Avellinotimes. KEY WORDS: Vesuvius; magma chamber; magma mixing; compositional layering phonolites; magma supply; potassic magmas
*Correponding author 相似文献
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DEFORMATIONAL BEHAVIOURS OF ALLUVIAL UNITS DETECTED BY ADVANCED RADAR INTERFEROMETRY IN THE VEGA MEDIA OF THE SEGURA RIVER,SOUTHEAST SPAIN
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ABSTRACT The paper deals with the estimation of the probability distribution of the yearly maximum of the peak discharge Q by means of the distribution of the maximum of the daily discharge q and the distribution of the ratio R = Q/q. The study was carried out for some catchments in Tuscany, analysing the dependence of the parameters of R on the geomorphic catchment parameters. The values of the discharge Q, relevant to an assigned return period, obtained by the methods given herein agree rather well (the error is about 20%) with those directly obtained from the observed values of Q. 相似文献