Late‐glacial to Holocene depositional architecture of the Ombrone palaeovalley system (Southern Tuscany,Italy): Sea‐level,climate and local control in valley‐fill variability          下载免费PDF全文

Anna Breda  Alessandro Amorosi  Veronica Rossi  Fabio Fusco 《Sedimentology》2016,63(5):1124-1148

The Ombrone palaeovalley was incised during the last glacial sea‐level fall and was infilled during the subsequent Late‐glacial to Holocene transgression. A detailed sedimentological and stratigraphic study of two cores along the palaeovalley axis led to reconstruction of the post‐Last Glacial Maximum valley‐fill history. Stratigraphic correlations show remarkable similarity in the Late‐glacial to early‐Holocene succession, but discrepancy in the Holocene portion of the valley fill. Above the palaeovalley floor, about 60 m below sea‐level, Late‐glacial sedimentation is recorded by an unusually thick alluvial succession dated back to ca 18 cal kyr bp . The Holocene onset was followed by the retrogradational shift from alluvial to coastal facies. In seaward core OM1, the transition from inner to outer estuarine environments marks the maximum deepening of the system. By comparison, in landward core OM2, the emplacement of estuarine conditions was interrupted by renewed continental sedimentation. Swamp to lacustrine facies, stratigraphically equivalent to the fully estuarine facies of core OM1, represent the proximal expression of the maximum flooding zone. This succession reflects location in a confined segment of the valley, just landward of the confluence with a tributary valley. It is likely that sudden sediment input from the tributary produced a topographic threshold, damming the main valley course and isolating its landward segment from the sea. The seaward portion of the Ombrone palaeovalley presents the typical estuarine backfilling succession of allogenically controlled incised valleys. In contrast, in the landward portion of the system, local dynamics completely overwhelmed the sea‐level signal, following marine ingression. This study highlights the complexity of palaeovalley systems, where local morphologies, changes in catchment areas, drainage systems and tributary valleys may produce facies patterns significantly different from the general stratigraphic organization depicted by traditional sequence‐stratigraphic models.  相似文献   

Establishment of ICL Italian network   总被引：1，自引：1，他引：0  

Nicola Casagli  Veronica Tofani 《Landslides》2018,15(10):1907-1908

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The development of folds in bedded chert and related rocks in the Malaguide Complex, southern Spain     

Miguel Orozco  Rafael Galvez 《Tectonophysics》1979,56(3-4)

Folds and folding mechanism in a chert sequence and related rocks of the Maláguide Complex (the uppermost tectonic unit of the Betic Zone) have been investigated. The geometric study shows that folds that developed in the chert sequence are usually angular in shape and asymmetric. Chevron and conjugate folds are common.Folding in bedded chert is explained in terms of a suggested model:

1. (1) Development of folds by kink and conjugate kinking.

2. (2) As the shortening increases, the interlimb angles decrease; in the kink folds this is caused by a reduction of the angle between the layers within the kink and the kink boundaries. There seems to be a relationship between this angle and the asymmetrical thinning-out in the limbs of many folds: the smaller is the angle between the kink boundary and the layers within the kink band, the larger is the reduction of the thickness in these layers.

Single limestone layers embedded in slate deform very probably by a buckling mechanism, implying tangential longitudinal strain and an additional flattening.  相似文献   

Crystal bending in metamorphic calcite,and its relations to associated twinning     

Francis J. Turner  Miguel Orozco 《Contributions to Mineralogy and Petrology》1976,57(1):83-97

This paper deals with the incidence and geometry of lattice bending in calcite of naturally strained marble and possible relations in time to associated {01¯12} twinning, as revealed by microscopic examination with a universal stage. Microscopic technique and graphic treatment of data with a view to identifying the relation in time of bending to twinning, and possible glide mechanisms involved in the bending process are reviewed as a basis for present and subsequent investigation of this general topic.In most instances development of surviving thin e twins postdates bending of the host crystal (such twins everywhere are rationally oriented). Rarely (in contrast with experimental experience) some thin twins are slightly irrational (L_e lamellae) and apparently developed in the final stages of bending. Thick twins (a few tens of microns wide) on the other hand rather commonly predate or are synchronous with bending.The geometry of bending (external rotation) — especially for rotation less than 25° —commonly is compatible with models (based on experimental experience) of simple translation in the strained domains. The commonest translation system so identified is on {10¯11}, with sense of shear, where recognizable, either negative or positive. Translation on {02¯21} is relatively rare. Unexpectedly there is rather strong but not conclusive evidence of translation on {0001} parallel to an a axis. This mechanism, hitherto never identified with certainty, is now here documented unequivocally in a crystal of calcite experimentally strained at 300° C, 5 kb.  相似文献   

Organochlorine contamination (PCBs and DDTs) in deep-sea fish from the Mediterranean sea     

Storelli MM  Perrone VG  Marcotrigiano GO 《Marine pollution bulletin》2007,54(12):1968-1971

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Quantitative hazard and risk assessment for slow-moving landslides from Persistent Scatterer Interferometry   总被引：6，自引：4，他引：2  

Ping Lu  Filippo Catani  Veronica Tofani  Nicola Casagli 《Landslides》2014,11(4):685-696

Preparation of reliable landslide hazard and risk maps is crucial for hazard mitigation and risk management. In recent years, various approaches have been developed for quantitative assessment of landslide hazard and risk. However, possibly due to the lack of new data, very few of these hazard and risk maps were updated after their first generation. In this study, aiming at an ongoing assessment, a novel approach for updating landslide hazard and risk maps based on Persistent Scatterer Interferometry (PSI) is introduced. The study was performed in the Arno River basin (central Italy) where most mass movements are slow-moving landslides which are properly within the detection precision of PSI point targets. In the Arno River basin, the preliminary hazard and risk assessment was performed by Catani et al. (Landslides 2:329–342, 2005) using datasets prior to 2002. In this study, the previous hazard and risk maps were updated using PSI point targets processed from 4 years (2003–2006) of RADARSAT images. Landslide hazard and risk maps for five temporal predictions of 2, 5, 10, 20 and 30 years were updated with the exposure of losses estimated in Euro (€). In particular, the result shows that in 30 years a potential loss of approximate €3.22 billion is expected due to these slow-moving landslides detected by PSI point targets.  相似文献   

EURD observations of interstellar radiation     

Jerry Edelstein  Stuart Bowyer  Eric J. Korpela  Michael Lampton  JoaquÍn Trapero  José F. Gómez  Carmen Morales  Veronica Orozco 《Astrophysics and Space Science》2001,276(1):177-185

The hot interstellar medium (ISM) has far-reaching effect upon thestructure of galaxies. Although ISM heating processes are fairly wellunderstood, after decades of study, the processes that cool the hotinterstellar medium remain obscure. The EURD spectrograph was designed tomeasure the diffuse cosmic background from 350 to 1100 Å in order tostudy the hot ISM and the mechanisms by which it sheds its energy. Wepresent the first analysis of EURD observations of the cosmic background.These EURD observations have proven to be far more sensitive than previouswork; compared to previous results, we have improved the limits to theintensity of 450 to 900 Å line emission from the ISM by one to twoorders of magnitude. Our limit to OVI 1032 Å / 1038 Å doublet of 7900ph s^-1 cm^-2 str^-1 is the lowest yet reported. The EURDlimits to line emission are less intense than predicted by a varietytheoretical models of the local ISM.  相似文献   

Holocene relative sea level changes in the Västervik-Gamlebyviken region on the southeast coast of Sweden,southern Baltic Sea     

Christos Katrantsiotis  Martin Dahl  Veronica Palm  Johan Rönnby  Thomas Andrén  Elinor Andrén 《Boreas: An International Journal of Quaternary Research》2023,52(2):206-222

We reconstruct the Holocene shore displacement of the Västervik-Gamlebyviken area on the southeast coast of Sweden, characterised by a maritime cultural landscape and archaeological significance since the Mesolithic. Sediment cores were retrieved from four lake basins that have been raised above sea level due to the postglacial land uplift and eustatic sea level changes after the melting of the Fennoscandian Ice Sheet. The cores were radiocarbon dated and analysed for loss on ignition and diatoms. The isolation thresholds of the basins were determined using LiDAR data. The results provide evidence for the initiation of the first Littorina Sea transgression in this area at 8.5 thousand calibrated years before present (cal. ka BP). A relative sea level rise by ∼7 m a.s.l. is recorded between 8.0 and 7.5 cal. ka BP with a highstand at ∼22 m a.s.l. between 7.5 and 6.2 cal. ka BP. These phases coincide with the second and third Littorina Sea transgressions, respectively, in the Blekinge area, southern Sweden and are consistent with the final deglaciation of North America. After 6.2 cal. ka BP, the relative sea level dropped below 22 m a.s.l., and remained at ∼20 m a.s.l. until 4.6 cal. ka BP coinciding with the fourth Littorina Sea transgression in Blekinge. From 4.6 to 4.2 cal. ka BP, the shore displacement shows a regression rate of 10 mm a⁻¹ followed by a slowdown with a mean value of 4.6 mm a⁻¹ until 1.6 cal. ka BP, when the relative sea level dropped below 3.3 m a.s.l. The Middle to Late Holocene highstand and other periods of minor sea level transgressions and/or higher salinity between 6.2 and 1.7 cal. ka BP are attributed to a combination of warmer climate and higher inflow of saline waters in the southern Baltic Sea due to stronger westerlies, caused by variations in the North Atlantic atmospheric patterns.  相似文献   

The effect of target properties on crater morphology: Comparison of central peak craters on the Moon and Ganymede     

Veronica J. BRAY  Gareth S. COLLINS  Joanna V. MORGAN  Paul M. SCHENK 《Meteoritics & planetary science》2008,43(12):1979-1992

Abstract— We examine the morphology of central peak craters on the Moon and Ganymede in order to investigate differences in the near‐surface properties of these bodies. We have extracted topographic profiles across craters on Ganymede using Galileo images, and use these data to compile scaling trends. Comparisons between lunar and Ganymede craters show that crater depth, wall slope and amount of central uplift are all affected by material properties. We observe no major differences between similar‐sized craters in the dark and bright terrain of Ganymede, suggesting that dark terrain does not contain enough silicate material to significantly increase the strength of the surface ice. Below crater diameters of ?12 km, central peak craters on Ganymede and simple craters on the Moon have similar rim heights, indicating comparable amounts of rim collapse. This suggests that the formation of central peaks at smaller crater diameters on Ganymede than the Moon is dominated by enhanced central floor uplift rather than rim collapse. Crater wall slope trends are similar on the Moon and Ganymede, indicating that there is a similar trend in material weakening with increasing crater size, and possibly that the mechanism of weakening during impact is analogous in icy and rocky targets. We have run a suite of numerical models to simulate the formation of central peak craters on Ganymede and the Moon. Our modeling shows that the same styles of strength model can be applied to ice and rock, and that the strength model parameters do not differ significantly between materials.  相似文献   

Rockfall seismic features analysis based on in situ tests:frequency,amplitude, and duration     

Liang FENG  Veronica PAZZI  Emanuele INTRIERI  Teresa GRACCHI  Giovanni GIGLI 《山地科学学报》2019,(5)

In the seismic event classification,determining the seismic features of rockfall is significantly important for the automatic classification of seismic events because of the huge amount of raw data recorded by seismic stations in continuous monitoring. At the same time, the rockfall seismic features are still not completely understood.This study concentrates on the rockfall frequency content, amplitude(ground velocity), seismic waveform and duration analysis, of an artificial rockfall test at Torgiovannetto(a former quarry in Central Italy). A total of 90 blocks were released in the test, and their seismic signals and moving trajectories were recorded by four tri-axial seismic stations and four cameras, respectively. In the analysis processing,all the artificial rockfall signal traces were cut separately and the seismic features were extracted individually and automatically. In this study, the relationships between a) frequency content and impacted materials, b) frequency content and the distance between block releasing position and seismic station(source-receiver distance) were discussed. As a result, we found that the frequency content of rockfall focuses on 10-60 Hz and 80-90 Hz within a source-receiver distance of 200 m, and it is well correlated with impacted material and source-receiver distance. To evaluate the difference between earthquake and rockfall, 23 clear earthquake signals recorded in a seven month-long continuous seismic monitoring, carried out with the four seismic stations, were picked out, according to the Italian national earthquakes database(INGV). On these traces we performed the same analysis as in the artificial rockfall traces, and two parameters were defined to separate rockfall events from earthquake noise. The first one, the amplitude ratio, is related to the amplitude variation of rockfall between two stations and is greater than that of earthquakes, because of the higher attenuation occurring for rockfall events, which consists in high frequencies whereas for earthquakes it consists in low frequencies. The other parameter, the shape of waveform of signal trace, showed a significant difference between rockfall and earthquake and that could be a complementary feature to discriminate between both. This analysis of artificial rockfall is a first step helpful to understand the seismic characteristics of rockfall, and useful for rockfall seismic events classification in seismic monitoring of slope.  相似文献