The Mediterranean Sea hosts two subduction systems along the convergent Africa-Eurasia plate boundary that have produced strong ground shaking and generated tsunamis. Based on historical descriptions ...and sedimentary records, one of these events, in 365 CE, impacted a broad geographical area, including tsunami evidence for distances of 700-800 km from the source event, qualifying it as a 'megatsunami'. Understanding how megatsunamis are produced, and where they are more likely, requires a better understanding of the different secondary processes linked to these events such as massive slope failures, multiple turbidity current generation, and basin seiching. Our sedimentary records from an extensive collection of cores located in distal and disconnected basins, identify turbidites which are analyzed using granulometry, elemental (XRF), micropaleontological, and geochemical data in order to reconstruct their coastal or marine source. The results show that the 365 CE basin floor sediments are a mixture of inner shelf and slope materials. The tsunami wave produced multiple far-field slope failures that resulted in stacked basal turbidites. It also caused transport of continent-derived organic carbon and deposition over basal turbidites and into isolated basins of the deep ocean. The composition of sediment in isolated basins suggests their deposition by large-scale sheet like flows similar to what has been caused by the Tohoku earthquake associated tsunamis. This is significant for rectifying and resolving where risk is greatest and how cross-basin tsunamis are generated. Based on these results, estimates of the underlying deposits from the same locations were interpreted as possible older megatsunamis.
Weathering of sulphide minerals produces a large variety of Fe-oxide-bearing ochreous, varicoloured precipitates and efflorescences of variably soluble sulphate salts. These secondary minerals play ...an important role in acid mine drainage processes and, more generally, for environmental pollution, since they can be either a sink or a source for acidity and toxic metals. At Libiola mine, eastern Liguria (Italy), the secondary minerals directly form through precipitation from acid sulphate waters within waste-rock dumps and outcropping mineralized bodies as well as within streams and runoff channels. Within waste-rock dumps they are present mainly as cement, filling the inter-clast porosity, and/or as coating and ephemeral efflorescences on the outcropping surfaces. Their stability represents a major environmental issue due to the potential importance of these phases in controlling metal distribution in the surface environment. This paper presents a detailed mineralogy and geochemistry characterisation of these materials, investigating the tendency for different types of secondary minerals (hardpans, ochreous consolidated precipitates, ochreous colloids, non ochreous colloids) to release metals after a simple mixing with deionised water for 12days. Within the different types of deposits, hardpans showed the lowest tendency to release metals, in contrast to ochreous colloids and ochreous concretions that gave the highest concentrations.
Nickel was the element most easily extracted by this treatment, even from non-ochreous colloids, while iron was much less readily leached. Dissolution experiments carried out on efflorescent sulphate salts demonstrated that these materials have a strong acid producing affinity which led to their complete dissolution. These results indicate that secondary phases associated with acid mine drainage can play an important role in controlling trace metal mobility, acting either as scavengers, to remove metals, from solutions or also as secondary sources of metal contamination during the interaction of these materials with surface waters.
•Mineralogy and chemistry of secondary minerals in acid mine drainage systems•Leaching test on secondary minerals associated to AMD•Evaluation of the role of mineral species in controlling the toxic metals mobility
The Calabrian Arc subduction system is part of the Africa–Eurasia plate boundary, is one of the most seismically active regions in the Mediterranean Sea, and has been struck repeatedly by destructive ...historical earthquakes. In this study, we investigate the effects of historical earthquakes on abyssal marine sedimentation through the analysis of the turbidite record. We collected gravity cores in tectonically controlled basins where the eastern Mediterranean pelagic sequence is interbedded with resedimented units. Textural, micropaleontological, geochemical, and mineralogical signatures reveal three turbidite events in the last millennium. We dated the turbidite sequences from two different cores using different radiometric methods, whereas the average time interval between successive turbidite beds was estimated from pelagic sediment thickness and sedimentation rates; chronologies were refined through age modeling that provided age ranges (2σ) of each turbidite bed. The results suggest that turbidite emplacement was triggered by three historical earthquakes recorded in the area (i.e., the 1908, 1693, and 1169 events); their magnitude, epicentral location, and associated tsunamis support causative faults located in the Ionian Sea. The source for all the turbidites, as inferred from their mineralogy, is the metamorphic basement outcropping in southern Calabria and/or northeastern Sicily. Turbidite composition and cable breaks for the 1908 event have been used to infer likely traveling paths and seismogenic faults in the subduction system. Our findings suggest that Ionian Sea turbidites represent more than 80% of sedimentation and may be seabed archives of paleo‐earthquakes capable of reconstructing seismicity back in time, during several earthquake cycles.
Key Points
We examine interplay between historical seismicity, mass failures and turbidites
We reconstruct chronology of earthquake triggered turbidites in the Ionian Sea
Turbidite composition has been used to reconstruct sediment source
The crystalline Bi6Te2O15 and Bi6Te2O13 phases with orthorhombic and cubic symmetries, respectively, were synthesized by solid-state reaction synthesis. A study of the thermal stability of both ...phases was carried out, being verified that the high temperature cubic phase can be kept at room temperature in a metastable condition during long time. The Raman scattering spectrum, optical reflectivity and photoluminescence emission of these phases were measured for the first time. The optical band gaps Eg = 3.29eV, for the orthorhombic phase, and Eg = 3.08eV, for the cubic phase, were calculated from the reflectivity spectra. Using the brick-layer model the electrical conductivity of a dense ceramic of Bi6Te2O15 was measured, taking in account the grain and grain-boundary effects.
•The orthorhombic Bi6Te2O15 is the stable phase at room temperatures.•The cubic phase Bi6Te2O13 is obtained at temperatures higher than 856 °C.•The cubic phase can be maintained at room temperatures for more than two year.•Maintaining the cubic phase suggest its technological use at ambient conditions.
The recurrence of mass-flow units within sapropel S1, an organic carbon-rich lower Holocene marker bed in the Eastern Mediterranean Sea, was used to study the interplay between earthquakes and ...sedimentation along the seismically active Calabrian Arc (Ionian Sea).
Nine turbidite beds interrupt anoxic conditions during the deposition of sapropel S1. Each of these turbidites is associated with sharp grain size and geochemical elemental anomalies (high Al and Si, low Ca and coarse-grained basal part marked by Zr peaks), and with displaced foraminiferal species from different bathymetric ranges. We used these proxies to identify turbidite beds also above and below the sapropel, where turbidite signature is less clear due to the absence of major color changes. Turbidite structure and composition, as well as comparison with historical seismoturbidites, suggest a seismic triggering for such mass flow events. The peculiar color, well-known composition, geochemistry and age of sapropel S1, make this unit a key bed within which turbidites may be considered a sort of sedimentary “bar code” recording high-energy events within the background pelagic sedimentation; deciphering this code will reconstruct paleo-seismicity in this well-defined stratigraphic interval.
The pelagic units bracketing turbidite beds were radiometrically dated, and the age of the sapropel S1, deduced through age modeling, is between 6.0 and 10.2kyrcalBP. The emplacement age of each turbidite was estimated considering the average time-interval between successive turbidite beds (from pelagic sediment thickness and sedimentation rate). Subsequently these ages were further refined through age modeling. In this way, we compiled a catalogue of mass flow events during sapropel S1 deposition, a time span long enough to include several earthquake cycles and allow reliable seismic and tsunami hazard assessment in this area.
In green: Zirconium elemental concentration profile (1mm resolution). Display omitted
•We examine interplay between historical seismicity, mass failures and turbidites during sapropel S1 deposition;•We reconstruct chronology of earthquake triggered turbidites in the Ionian Sea during sapropel depostion;•We reconstruct the age of sapropel S1 in our core (6.0-10.2 kyr cal. BP) through Oxcal age modeling;•Turbidite emplacement time was deduced through age modeling.•We compiled a catalogue of mass flow events during several earthquake cycles.
► The main objective of this work is the synthesis of mesocrystal PZT by microwave hydrothermal method. ► Scanning electron microscopy indicates mesocrystals formed by micro-cubes. ► The PZT ...particles present photoluminescent (PL) behavior in green region, around 600nm. ► The PL analysis is an efficient technique for the available structural order–disorder of materials.
Micro-cube-shaped lead zirconate titanate was synthesized using the microwave-assisted hydrothermal method. Photoluminescence and field emission scanning electron microscopy were used for monitoring the formation of mesocrystals. Based on these results, a growth mechanism was then proposed which involved nanoparticle aggregation, nanoplate self-assembly on specific architecture and the final formation of mesoscopic micro-cube-shaped lead zirconate titanate.
The aim of this study was to evaluate the physiological, zootechnical, and environmental benefits of the use of growth-promoting virginiamycin in the pirarucu diet. The research was conducted at the ...Carlos Eduardo Matiazze Fish Center, Federal University of Rondônia. In this study, 96 pirarucu fish were distributed in excavated nursery, divided into two treatment groups, control (0.0 mg kg−1) and treatment (75.0 mg kg−1) of feed with virginiamycin, with 8 replications in a completely randomized design. With virginiamycin being incorporated into commercial feed, for 107 days of cultivation, the fish were slaughtered with an average weight of 9.18 kg. Carcass weight, flesh, residues, and internal organs/guts were evaluated to calculate slaughter yields, Spearman’s correlation, and subsequently regression. For the quantification of micronuclei, a count of 1,000 cells per blade was determined. The means of the results obtained were contrasted by the Student’s t-test (α = 0.05). Virginiamycin did not cause oscillations in the limnological variables of the nursery but could reduce micronucleated erythrocytes. The average yields in carcass, flesh, and waste were 67.43, 53.4, and 43.14%, respectively. Virginiamycin provided strong correlations (ρ2) for better productive yields and lower slaughter residue. The hepatosomatic index indicated a strong relationship between liver weight and fat. Virginiamycin may be recommended for fish farming in pirarucu fattening because it contributes to the productive efficiency and sustainability of the fish farm system.
Lead Titanate Zirconate (PZT) perovskite powders were synthesized by microwave hydrothermal method (M-H) at 180
°C for different time periods (2, 4, 8 and 12
h) with the presence of aqueous polyvinyl ...alcohol (PVA) solution 0.36
g
L
−1. The X-Ray diffraction (XRD), SE-FEG as well as the measurements of photoluminescence (PL) emission were used for monitoring the formation of a perovskite phase with random polycrystalline distortion in the structure. Emission spectra with fixed excitation wavelength of 350
nm showed higher value for the powder obtained after undergoing 8
h of treatment. A theoretical model derived from previous calculations allows us to discuss the origin of photoluminescence emission in the powders, which can be further related to the local disorder in the network of both ZrO
6 and TiO
6 octahedral, and dodecahedral PbO
12. The new morphology initially observed from the PZT perovskite crystal growth bearing the shape of fine plates is found to be directly related to photoluminescence emission with energy lower than that present in the PZT with cube-like morphology that emits in 560
nm.
► This work details the efficiency of microwave hydrothermal synthesis in obtaining PZT powders. ► PVA is used as a crystallization agent of PZT particles. ► PZT particles presented photoluminescent (PL) behavior. ► There aren't previous reports of photoluminescent PZT obtained by microwave hydrothermal synthesis. ► Photoluminescence is one more interesting property for technological applications this material.
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