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排序方式: 共有353条查询结果,搜索用时 31 毫秒
81.
Stefano Catalano Giuseppe Grasso Paolo Mazzoleni Carmelo Monaco Luigi Tortorici 《地学学报》2007,19(4):287-293
On the axial zone of the Southern Apennines the major tectonic boundary between the inner platform (Western platform unit) and the pelagic (Lagonegro units) domains is represented by a thick level of highly deformed rock‐assemblage. Structural analysis reveals that this tectonic unit represents an intracontinental melange complex characterized by a block‐in‐matrix fabric that contains blocks from both hangingwall platform and footwall basin units. This unit comprises different sets of structures that, caused by shearing processes, developed at depths ranging from about 8–9 km to the surface. These tectonites represent the product of a crustal shear zone developed at the major boundary between platform‐basin domains of Adria during the thick‐skinned tectonic processes controlling the Southern Apennines mountain building. 相似文献
82.
83.
Mucerino Luigi Carpi Luca Schiaffino Chiara F. Pranzini Enzo Sessa Eleonora Ferrari Marco 《Natural Hazards》2021,105(1):137-156
Natural Hazards - Rip currents are one of the most significant environmental hazards for beachgoers and are of interest to coastal scientists. Several studies have been conducted to understand rip... 相似文献
84.
Microscopic impactor debris in the soil around Kamil crater (Egypt): Inventory,distribution, total mass,and implications for the impact scenario 下载免费PDF全文
Luigi Folco Massimo D'Orazio Agnese Fazio Carole Cordier Antonio Zeoli Matthias van Ginneken Ahmed El‐Barkooky 《Meteoritics & planetary science》2015,50(3):382-400
We report on the microscopic impactor debris around Kamil crater (45 m in diameter, Egypt) collected during our 2010 geophysical expedition. The hypervelocity impact of Gebel Kamil (Ni‐rich ataxite) on a sandstone target produced a downrange ejecta curtain of microscopic impactor debris due SE–SW of the crater (extending ~300,000 m2, up to ~400 m from the crater), in agreement with previous determination of the impactor trajectory. The microscopic impactor debris include vesicular masses, spherules, and coatings of dark impact melt glass which is a mixture of impactor and target materials (Si‐, Fe‐, and Al‐rich glass), plus Fe‐Ni oxide spherules and mini shrapnel, documenting that these products can be found in craters as small as few tens of meters in diameter. The estimated mass of the microscopic impactor debris (<290 kg) derived from Ni concentrations in the soil is a small fraction of the total impactor mass (~10 t) in the form of macroscopic shrapnel. That Kamil crater was generated by a relatively small impactor is consistent with literature estimates of its pre‐atmospheric mass (>20 t, likely 50–60 t). 相似文献
85.
Antarctic marine bacteria were screened for their ability to degrade polychlorinated biphenyls (PCB) as the sole carbon and energy source at both 4 degrees C and 15 degrees C. PCB-degrading isolates (7.1%) were identified by sequencing their 16S rDNA as Pseudoalteromonas, Psychrobacter and Arthrobacter members. One representative isolate per genera was selected for evaluating the biodegradative potential under laboratory scale and phenotypically characterized. Removal of individual PCB congeners was between 35.6% and 79.8% at 4 degrees C and between 0.4% and 82.8% at 15 degrees C. Differences in the removal patterns of PCB congeners were observed in relation to the phylogenetic affiliation: Arthrobacter isolate showed similar biodegradation efficiencies when growing at 4 degrees C and 15 degrees C, while Pseudoalteromonas better degraded PCBs at 15 degrees C. No biodegradation was detected for Psychrobacter isolate at 4 degrees C. Results obtained highlight the occurrence of PCB-degrading bacteria in Antarctic seawater and suggest the potential exploitation of autochthonous bacteria for PCB bioremediation in cold marine environments. 相似文献
86.
Fabrizio Antonioli Luigi Ferranti Kurt Lambeck Steve Kershaw Vladimiro Verrubbi Giuseppe Dai Pra 《Tectonophysics》2006,422(1-4):23-40
A combination of published and new radiometric dates on uplifted Holocene fossil beaches from northeastern Sicily and southern Calabria (southern Italy) is compared with the altitude of the inner margin of the Last Interglacial (LIg) (Late Pleistocene, 124 ka) and older marine terraces in order to gain a regional-scale outline of uplift rates and their temporal changes in a region which is one of the fastest uplifting sectors of the Central Mediterranean Sea. Late Holocene radiocarbon dates from Ioppolo (southern Calabria) and Ganzirri (northeast Sicily), two newly discovered sites are here presented for the first time. The Holocene uplift rates are highest at St. Alessio and Taormina in eastern Sicily (2.4 mm/y) and at Scilla in southwestern Calabria (2.1 mm/y), two sites located across the Messina Straits and which separate the island of Sicily from mainland Italy. Uplift rates decrease towards the south and north from this centre of uplift. Late Holocene uplift rates show an apparent increase of between 64 and 124% when compared with the longer-term uplift rates calculated from the LIg highstand terraces. Furthermore, we discovered that the locations of fastest Late Pleistocene and Late Holocene uplift rates spatially coincide. To what extent the Holocene increase in uplift rates results from incomplete elastic strain release along the major extensional faults which frame the seismotectonic of the area, or indicate a true change in regional tectonic processes, is not resolved. Nonetheless, the heterogeneity of uplift, with a well-defined centre that crosses the Messina Straits, and its persistence at different time-scales indicates a tight connection between wider regional processes and fault-related displacement in controlling crustal instability in this area. 相似文献
87.
U-Pb Zircon Geochronology with an Integrated LA-ICP-MS Microanalytical Workstation: Achievements in Precision and Accuracy 总被引:1,自引:0,他引:1
Luigi A. Solari Arturo Gómez-Tuena Juan Pablo Bernal Ofelia Pérez-Arvizu Martin Tanner 《Geostandards and Geoanalytical Research》2010,34(1):5-18
Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) is a microanalytical tool especially suitable for providing fast and precise U-Pb geochronological results on zircon grains. A new 193 nm excimer laser adapted to a micromachining workstation, equipped with a newly designed two-volume ablation cell and coupled with a quadrupole ICP-MS, is presented here. The system was tuned routinely to achieve sensitivities in the range of 3000 cps/μg g−1 for 238 U (< 2% RSD), with a 34 μm spot size, at 5 Hz and ∼ 8 J cm−2 , while ablating the NIST SRM 612 glass reference material. The system was capable of providing fast (< 1.5 minutes each analysis) and precise (generally < 1.5% 1s errors) 206 Pb/238 U zircon ages. The ages of widely used reference material zircons (Plesovice, 337 Ma; Temora, 416 Ma; R33, 418 Ma; Sri Lanka, 564 Ma; 91500, 1065 Ma) could be precisely matched, with an accuracy on isotopic ratios that ranged from ∼ 2 to ∼ 6%, depending on the homogeneity of the natural reference materials. 相似文献
88.
89.
Constitutive equations for drained cohesionless soils under triaxial stress states, based on a microslip model with internal friction, are proposed and applied to the analysis of the seismic response of soil deposits. The microslips, assumed localized in the discontinuity surfaces passing through the particle-to-particle contacts, describe the effects of the sliding and rolling between grains of sand. Once the response of the model under cyclic shearing stresses and strains superimposed on the geostatic stress state has been analysed, the constitutive equations are applied to a one-dimensional shear model for the dynamic analysis of the layered deposits. An application to an instrumented soil deposit is then developed, the experimental results of which refer to both strong and weak motion earthquakes; the comparisons between the experimental and theoretical results point out the peculiarities and validity limits of the model. The model here developed may be applied also to the analysis of two- and three-dimensional sites. 相似文献
90.
Diesel oil and PCB-degrading psychrotrophic bacteria isolated from Antarctic seawaters (Terra Nova Bay, Ross Sea) 总被引:2,自引:0,他引:2
Maria De Domenico Angelina Lo Giudice Luigi Michaud Marcello Saitta Vivia Bruni 《Polar research》2004,23(2):141-146
Fifty-seven Antarctic marine bacteria were examined for their ability to degrade commercial diesel oil as the sole organic substrate at both 4 °C and 20 °C. Based on the preliminary screening, two isolates (B11 and B15) with high capacity to degrade diesel oil were selected and their biodegradation efficiency was quantified by gas chromatographic analysis. As expected for psychrotrophs, diesel oil biodegradation was slower at 4 °C than at 20 °C. The two strains also mineralized the C28 n-paraffin octacosane at 20 °C and polychlorinated biphenyls (PCBs) at 4 °C and 20 °C. 相似文献