Environmental History of Lago di Tovel,Trento, Italy,Revealed by Sediment Cores and 3.5 kHz Seismic Mapping   总被引：1，自引：0，他引：1  

Thomas?KulbeEmail author  Flavio?Anselmetti  Marco?Cantonati  Michael?Sturm 《Journal of Paleolimnology》2005,34(3):325-337

Proxy data from a total of 30 sediment cores and information from a seismic survey show that the sedimentological and limnological history of Lago di Tovel (1178 m a.s.l.) has been significantly influenced by slope dynamics of its mountainous catchment. The lake represents a dead-ice lake with pro-glacial deposits at the base of its sedimentary record. A prominent lake level rise in 1597/1598 that increased maximum water depth from ∼20 to 39 m caused slope instabilities, leading to the deposition of mass-flow sediments with a maximum thickness of 2.5 m in the northern part of the lake and less than 50 cm in the southern part, resulting in a total volume of more than 113,000 m³. Consequently, a rough lake bottom morphology was produced, which led to distinct differences in sedimentation rates of 0.07 cm yr⁻¹ on sills and 0.18 cm yr⁻¹ within depressions. The age of the top of the mass-flow deposits was used to validate the ages of the younger, laminated sediments, which were dated by ²¹⁰Pb and ¹³⁷Cs. Lithological investigations showed that the sediments below the mass-flow deposits are also laminated and that they were not bioturbated. The long-term meromixis of Lago di Tovel is therefore mainly due to a combination of its topographic setting and the 5-month period of ice cover. Both prevent effective mixing of the lake by strong winds during spring and autumn. Distinct spatial differences in sediment distribution within the lake show that it is risky to interpret proxy data from only one coring site, even if the lake is very small. This is especially true in mountainous areas, where rock falls, mass movements, and slope instabilities of a significant size may have considerable effects on lakes.  相似文献   

Cenomanian florule of Nammoura, Lebanon     

Valentin Krassilov  Flavio Bacchia 《Cretaceous Research》2000,21(6):785

The mid-Cenomanian fish beds of Nammoura, Mont-Liban district, Lebanon contain a diverse fauna of aquatic and terrestrial vertebrates, a few crustaceans and moderately well-preserved plant remains of which a single species,Sapindopsis anhouryi , was previously described by Dilcher & Basson (1990). We add 11 species of ferns, gymnosperms and angiosperms of which Nammouria cretacea gen. et sp. nov, Nupharanthus cretacea gen. et sp. nov., Sapindopsis libanensis sp. nov. and Nammourophyllum altingioides gen. et sp. nov. are new taxa. The florule differs markedly from both Early Cretaceous and Turonian plant assemblages of the Middle East, thereby representing a distinct stage of the regional floristic evolution. Its phytogeographic affinities are with contemporaneous floras of North America, Central Europe and the Crimea. A combination of such features as xeromorphism, the prevalence of compound leaves, and the presence of deciduous angiosperm components and gymnosperms may indicate climatic conditions similar to those of the present day Mediterranean.  相似文献   

Recent anthropogenic impact in ancient Lake Ohrid (Macedonia/Albania): a palaeolimnological approach     

Julia Lorenschat  Xiaosen Zhang  Flavio S. Anselmetti  Jane M. Reed  Martin Wessels  Antje Schwalb 《Journal of Paleolimnology》2014,52(3):139-154

Ancient lakes, which are important centres of biodiversity and endemism, are threatened by a wide variety of human impacts. To assess environmental impact on ancient Lake Ohrid we have taken short sediment cores from two contrasting site locations, comprising a site of urban pollution and an apparently pristine area. Recent impacts on water quality and ecology were assessed using sediment, geochemical, ostracode, and diatom data derived from analysis of two ²¹⁰Pb-dated sediment cores spanning the period from 1918 to 2009. According to the index of geoaccumulation, sediments were often moderately contaminated with As. Fe and Ni concentrations often exceeded reported maximum limits above which harmful effects on sediment-dwelling organisms are expected. Productivity in the (pristine) south-eastern part of Lake Ohrid (Sveti Naum) is generally lower than in the north, probably due to the strong influence of spring discharge. Low ostracode and diatom concentrations, low abundance of the epilimnetic diatom Cyclotella ocellata, and low values of TOC and TIC indicate a lower productivity from the early 1920s to the late 1980s. Since the mid 1970s, increased relative abundance of C. ocellata and increasing diatom concentration indicate increasing productivity in the south-eastern part. Rising numbers of ostracode valves and higher TIC and TOC contents in both sediment cores indicate an increase in productivity during the late 1980s. A slight increase in productivity near Sveti Naum continued from the early 1990s until 2009, witnessed by rising TC, TIC, and TOC content and a generally high number of ostracode valves and ostracode diversity. The area near the City of Struga (site of urban pollution) is also characterized by rising TOC and TIC contents and, furthermore, by increasing Cu, Fe, Pb, and Zn concentrations since the early 1990s. The recent reduction in the number of ostracode valves and ostracode diversity is probably caused by a higher heavy metal load into the lake. This suggests that living conditions for the endemic species in Lake Ohrid have become less favourable in the northern part of the lake, which might threaten the unique flora and fauna of Lake Ohrid.  相似文献   

Mapping basin-wide subaquatic slope failure susceptibility as a tool to assess regional seismic and tsunami hazards     

Strasser  Michael  Hilbe  Michael  Anselmetti  Flavio S. 《Marine Geophysical Researches》2011,32(1-2):331-347

Marine Geophysical Research - This study of subaquatic slope failures in Lake Lucerne, central Switzerland, presents a new concept for evaluating basin-wide slope stability through time as a...  相似文献   

The discovery of clumpy structure in the diffuse gas towards Cyg OB2 No. 12     

Flavio Scappini  Silvia Casu  Cesare Cecchi-Pestellini  Michael Olberg 《Monthly notices of the Royal Astronomical Society》2002,337(2):495-498

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Subaqueous landslide-triggered tsunami hazard for Lake Zurich,Switzerland     

Michael Strupler  Michael Hilbe  Katrina Kremer  Laurentiu Danciu  Flavio S. Anselmetti  Michael Strasser  Stefan Wiemer 《Swiss Journal of Geoscience》2018,111(1-2):353-371

Subaqueous landslides can induce potentially damaging tsunamis. Tsunamis are not restricted to the marine environment, but have also been documented on lakes in Switzerland and worldwide. For Lake Zurich (central Switzerland), previous work documented multiple, assumedly earthquake-triggered landslides. However, no information about past tsunamis is available for Lake Zurich. In a back-analysis, we model tsunami scenarios as a consequence of the earthquake-triggered landslides in the past. Furthermore, on the basis of a recent map of the earthquake-triggered subaqueous landslide hazard, we present results of a tsunami hazard assessment. The subaqueous landslide progression, wave propagation and inundation are calculated with a combination of open source codes. Although no historic evidence of past tsunamis has been documented for Lake Zurich, a tsunami hazard exists. However, only earthquakes with long return periods are assumed to cause considerable tsunamis. An earthquake with an exceedance probability of 0.5% in 50 years (corresponding to an earthquake with a return period of 9975 years) is assumed to cause tsunamigenic landslides on most lateral slopes of Lake Zurich. A hypothetical tsunami for such an event would create damage especially along the shores of the central basin of Lake Zurich with estimated peak flow depths of up to ~?4.6 m. Our results suggest that for an earthquake with an exceedance probability of 10% in 50 years (i.e., mean return period of 475 years), no considerable tsunami hazard is estimated. Even for a worst-case scenario, the cities of Zurich and Rapperswil, located at the northern and southern ends of the lake, respectively, are assumed to experience very little damage. The presented first-order results of estimated wave heights and inundated zones provide valuable information on tsunami-prone areas that can be used for further investigations and mitigation measures.  相似文献   

Multiple Quaternary erosion and infill cycles in overdeepened basins of the northern Alpine foreland     

Marius W. Buechi  Hans Rudolf Graf  Peter Haldimann  Sally E. Lowick  Flavio S. Anselmetti 《Swiss Journal of Geoscience》2018,111(1-2):133-167

The cumulative effect of repeated extensive glaciations represents a poorly constrained component in the understanding of landscape evolution in mid-latitude mountain ranges such as the Alps. Timing, extent, and paleo-climatic conditions of these glaciations are generally poorly understood due to the often-fragmentary character of terrestrial Quaternary records. In this context, the sedimentary infills of subglacial basins may serve as important archives to complement the Quaternary stratigraphy over several glacial–interglacial cycles. In this study, sedimentary facies, valley-fill architecture, and luminescence dating are used to describe nine erosional and depositional cycles (Formations A–I) in the Lower Glatt valley, northern Switzerland. These cycles can be related to the ‘Birrfeld’ Glaciation (~ MIS2), the ‘Beringen’ Glaciation (~ MIS6), and up to three earlier Middle Pleistocene glaciations that can be tentatively correlated to the regional glaciation history. Evidence suggests that deep bedrock trough incision and/or partial re-excavation last occurred mainly during the ‘Beringen’ and ‘Habsburg’ Glaciations. Second-order, ‘inlaid’ glacial basins document separate glacier re-advances during the Beringen Glaciation. The arrangement of subglacial basins in the Glatt valley with different sub-parallel or bifurcating bedrock troughs, re-excavated segments, and inlaid basins document changes in the magnitude and the spatial focus of subglacial erosion over time. The Glatt valley may thus serve as a key example for the glacial landscape evolution in many other repeatedly glaciated forelands.  相似文献   

Signatures of slope failures and river‐delta collapses in a perialpine lake (Lake Lucerne,Switzerland)     

Michael Hilbe  Flavio S. Anselmetti 《Sedimentology》2014,61(7):1883-1907

Historical reports from the 17th Century document two destructive tsunamis with run‐ups exceeding 5 m, affecting proximal basins of Lake Lucerne (Switzerland). One event in ad 1601 is coeval with a strong nearby earthquake (M_W ca 5·9) which caused extensive slope failures in many parts of the lake. The second event in ad 1687 is associated with an apparently spontaneous partial collapse of the Muota river delta. This study combines high‐resolution bathymetry, reflection seismic and lithological data to document the sedimentary and morphological signatures of the two subaqueous mass movements that probably generated the observed tsunamis. Such mass movements are significant as a common sedimentation process and as a natural hazard in fjord‐type lakes and similar environments. The deposits, covering large parts of the basins with thicknesses reaching >10 m, consist of two subunits: A lower ‘massflow deposit’ contains variably deformed sediments from the source areas. Its emplacement affected pre‐existing sediments, incorporating thin sediment slices into the deposit and increasing its volume. Deep‐reaching deformation near basin margins is expressed as bulges on the lake floor. An overlying ‘megaturbidite’, featuring a graded, sandy base and a thick homogeneous muddy part, was deposited from suspended particles. The source area for the ad 1601 event, gently dipping lateral slopes with an unconsolidated hemipelagic sediment cover, hosts a pronounced slide scar with sharp escarpments and sliding surfaces. The source area for the ad 1687 event on an active delta slope has been overprinted by continued sedimentation and does not show an unambiguous scar. The case studies are exemplary for end‐member types of source areas (lateral versus delta slopes) and trigger mechanisms (seismic versus aseismic); they show that morphological mapping and reconstructions of past events are key components of a hazard assessment for mass movement‐generated tsunamis.  相似文献   

IT-OSRA: applying ensemble simulations to estimate the oil spill risk associated to operational and accidental oil spills     

Antonio Augusto Sepp Neves  Nadia Pinardi  Flavio Martins 《Ocean Dynamics》2016,66(8):939-954

Oil Spill Risk Assessments (OSRAs) are widely employed to support decision making regarding oil spill risks. This article adapts the ISO-compliant OSRA framework developed by Sepp Neves et al. (J Environ Manag 159:158–168, 2015) to estimate risks in a complex scenario where uncertainties related to the meteo-oceanographic conditions, where and how a spill could happen exist and the risk computation methodology is not yet well established (ensemble oil spill modeling). The improved method was applied to the Algarve coast, Portugal. Over 50,000 simulations were performed in 2 ensemble experiments to estimate the risks due to operational and accidental spill scenarios associated with maritime traffic. The level of risk was found to be important for both types of scenarios, with significant seasonal variations due to the the currents and waves variability. Higher frequency variability in the meteo-oceanographic variables were also found to contribute to the level of risk. The ensemble results show that the distribution of oil concentrations found on the coast is not Gaussian, opening up new fields of research on how to deal with oil spill risks and related uncertainties.  相似文献   

Defining Geodetic Reference Frame using Matlab®: PlatEMotion 2.0     

Flavio Cannavò  Mimmo Palano 《Pure and Applied Geophysics》2016,173(3):937-944

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