Liquefaction-induced structures in Quaternary alluvial gravels and gravelly sediments, NE Brazil

We have identified numerous well-preserved elutriation and fluidization structures probably induced by liquefaction in Quaternary gravels and gravelly sediments of braided fluvial channel deposits in the Rio Grande do Norte and Ceará states, northeastern Brazil. They show evidence of upward-directed water escape after sediment deposition and before sediment compaction. Among the several types of structures observed, the most frequent are pillars, pockets and dikes. These structures range in width from a few centimeters to as much as 4 m, and in height from 60 cm to 4 m. Dikes, pillars and pockets are systematically associated. Clastic dikes vented large quantities of sand to the upper layers or the surface; pebbles and cobbles from the host rock sank into the dikes and formed pillars and pockets. Pockets form the root part; pillars form the intermediate part and dike, the upper part of the composite structure. The morphology of the structures in sectional and plan views indicates a 3D geometry composed of a tabular dike and pillar that present a downward continuous transition to a bowl-shaped pocket. This “stratigraphy” of liquefaction features is different from that usually presented in the current literature.

Field data suggest that both the location and the geometry of the features were controlled by sedimentary properties rather than joints and small faults. The size and abundance of these features suggest that they were formed by great events rather than localized mechanisms. Field evidence also indicates that these features are the product of fluidization and elutriation and may have been induced by liquefaction processes associated with seismic shaking. A nonseismic origin related to elutriation processes, however, cannot be ruled out for some of the features.     

Assessment of physical vulnerability and potential losses of buildings due to shallow slides

Physical vulnerability (PV) of buildings and associated potential losses (PLs) due to the occurrence of shallow slides are semi-quantitatively assessed at the regional scale in a municipality located in the North of Portugal. This work has four main purposes: (1) to identify and characterize the built environment exposed to shallow slides in the study area; (2) to assess the PV of each building type taking into account the building resistance (BR) and the landslide magnitude (LM); (3) to evaluate the economic value (EV) of each single exposed building using cadastral and market values; and (4) to estimate PLs on buildings due to landslide activity. The analysis is made for each single building of the study area, and this is an innovative contribution of this work. The semi-quantitative methodology to assess PV of buildings exposed to shallow translational slides combines the LM and the BR, which is empirically obtained weighting a set of parameters related to building characteristics. The quantification of the EV of buildings was carried out using an adaptation of the calculation formula used by the Portuguese Tax Services to determine the taxable value of buildings in Portugal. PLs result from the product between PV of the exposed buildings and their EV in euros. The overlapping of PLs of buildings with an available landslide susceptibility map, although does not provides any quantified risk analysis, provides valuable information to be used by spatial planning and civil protection stakeholders.     

Tectonically controlled sedimentation: impact on sediment supply and basin evolution of the Kashafrud Formation (Middle Jurassic,Kopeh-Dagh Basin,northeast Iran)

The Kashafrud Formation was deposited in the extensional Kopeh-Dagh Basin during the Late Bajocian to Bathonian (Middle Jurassic) and is potentially the most important siliciclastic unit from NE Iran for petroleum geology. This extensional setting allowed the accumulation of about 1,700 m of siliciclastic sediments during a limited period of time (Upper Bajocian–Bathonian). Here, we present a detailed facies analysis combined with magnetic susceptibility (MS) results focusing on the exceptional record of the Pol-e-Gazi section in the southeastern part of the basin. MS is classically interpreted as related to the amount of detrital input. The amount of these detrital inputs and then the MS being classically influenced by sea-level changes, climate changes and tectonic activity. Facies analysis reveals that the studied rocks were deposited in shallow marine, slope to pro-delta settings. A major transgressive–regressive cycle is recorded in this formation, including fluvial-dominated delta to turbiditic pro-delta settings (transgressive phase), followed by siliciclastic to mixed siliciclastic and carbonate shoreface rocks (regressive phase). During the transgressive phase, hyperpycnal currents were feeding the basin. These hyperpycnal currents are interpreted as related to important tectonic variations, in relation to significant uplift of the hinterland during opening of the basin. This tectonic activity was responsible for stronger erosion, providing a higher amount of siliciclastic input into the basin, leading to a high MS signal. During the regressive phase, the tectonic activity strongly decreased. Furthermore, the depositional setting changed to a wave- to tide-dominated, mixed carbonate–siliciclastic setting. Because of the absence of strong tectonic variations, bulk MS was controlled by other factors such as sea-level and climatic changes. Fluctuations in carbonate production, possibly related to sea-level variations, influenced the MS of the siliciclastic/carbonate cycles. Carbonate intervals are characterized by a strong decrease of MS values indicates a gradual reduction of detrital influx. Therefore, the intensity of tectonic movement is thought to be the dominant factor in controlling sediment supply, changes in accommodation space and modes of deposition throughout the Middle Jurassic sedimentary succession in the Pol-e-Gazi section and possibly in the Kopeh-Dagh Basin in general.     

The application of FAMM (Fluorescence Alteration of Multiple Macerals) analyses for evaluating rank of Paraná Basin coals, Brazil

Combining vitrinite reflectance (VR) and fluorescence alteration of multiple macerals (FAMM) analyses provide insights into the chemical nature of vitrinites (i.e., perhydrous vs. orthohydrous vs. subhydrous compositions) in Permian Gondwana coals of the Paraná Basin, Brazil. The FAMM-derived equivalent VR (EqVR) values and relationships with VR can be determined according to calibration curves based largely on Permian Gondwana coals of eastern Australia.The analytical results indicate that vitrinites in the Paraná Basin coals studied generally range from orthohydrous to perhydrous, with interpreted VR suppression ranging up to 0.2% absolute for the most perhydrous case. The EqVR values of the Santa Catarina coals, which range from about 0.85% to 0.95% differ from VR values by about 0.10–0.15% absolute, potentially having significant implications on coal utilization.The causes of vitrinite reflectance suppression in the Paraná Basin coals are as yet poorly understood, but are likely to be related to a combination of factors.     

Nanomineralogy of evaporative precipitation of efflorescent compounds from coal mine drainage

Efflorescent nanophases(NPs)are found as a transitory accumulation of potentially hazardous elements(PHEs),particularly in tropical climates.The central objective of this study was to investigate the distribution of PHEs with NPs through the evaporative formation structures(EFS)of enormously PHEs-rich coal-mine drainages(CMD).The EFS were studied in natural coal mine drainage for five months in order to determine their geochemical and ecological structures and to assess their position in the reduction of PHEs in nature.The largest coal-fired power plant in South America,located in south Brazil,is used as an example of such a problem.In this work,a novel methodology for the analysis of PHEs in CMD precipitates is proposed for this affected coal area.The analytical method,combining X-Ray Diffraction(XRD)and advanced electron microscopies,shows the importance of nanomineralogy in understanding different circumstances of coal contamination.Several ultrafine-nanoparticles(UNPs)were identified in the sampled soils and river sediments together with the PHEs.A decrease in PHEs was identified in association with UNPs.However,further investigations are required with regard to the mobility of PHEs in water,atmosphere,soils,and sediments.The EPS was thoroughly studied,acquiring suitable understanding with investigational facts for Ca and Fe-sulphates,pickeringite,and several amorphous phases.     

Hydrofluoric Acid‐Free Digestion of Geological Samples for the Quantification of Rare Earth Elements by Inductively Coupled Plasma‐Optical Emission Spectrometry

Rare earth elements (REEs) are very important to technological development as well as to geochemical and environmental studies. In this work, hydrofluoric acid (HF) was replaced by condensed phosphoric acid (CPA) in the digestion of geological samples, and the quantification of REEs was performed by inductively coupled plasma‐optical emission spectrometry (ICP‐OES). Six international reference materials (RMs), named DC86318, CGL 111, CGL 124, CGL 126, OKA‐2 and COQ‐1 and three Brazilian ore samples, named Araxá, Catalão and Pitinga were analysed. Only zircon and xenotime, which are potential REE‐bearing minerals, were not completely dissolved. Nevertheless, no REE associated with zircon was detected. The investigated digestion method presented many advantages: It was relatively fast (3 h), avoided fluoride precipitation, it was less hazardous because handling diluted H₃PO₄ is safer than HF, NH₄F or NH₄HF₂ aqueous solutions, it preserved the quartz fittings of the measurement equipment and the final solution contained lower levels of total dissolved solids than those produced by the fusion method.     

Spatial distribution and estimation of rainfall trends and erosivity in the Epitácio Pessoa reservoir catchment,Paraíba,Brazil

Natural Hazards - The main goals of this study are to better understand the spatial and temporal variabilities in rainfall and to identify rainfall trends and erosivity for the period from 1963 to...     

张全庄金矿元素地球化学特征及找矿意义

张全庄金矿是河北省一危机矿山.矿山多为采空区,矿脉中硫化物分布不均匀.矿脉的不同围岩为统一的元素地球化学整体.通过采取与矿脉等距近矿蚀变岩,研究这些蚀变岩中元素的带入带出特征,分析成矿规律,建立了张全庄金矿矿脉原生晕元素组合分带模式,即As、Sb、Ag等元素为头晕元素,Cu、Ag、Au、Pb、Zn等元素为矿中元素,Mo为尾晕元素.运用此模式对张全庄金矿进行深部成矿预测,成功地发现了新矿体.     

Nitrogen uptake in light versus darkness of the seagrass Zostera noltei: integration with carbon metabolism

We conducted a study that shows that light and dark conditions do not affect the uptake rates of ammonium and nitrate by the seagrass Zostera noltei. This is an important advantage over some seaweed species in which these rates are severely reduced at night. In the light, the ammonium uptake rates were initially higher (15 and 20 μmol·g^?1·h^?1) and stabilized at a rate of 5 μmol·g^?1·h^?1 after 1 h, whereas in the dark the rates remained constant at a rate of 10 μmol·g^?1·h^?1 over the first 180 min of incubation. The rates of nitrate uptake in the light were high within the first 120 min of incubation (7.2–11.1 μmol·g^?1·h^?1) and decreased afterwards to lower values (0.8–3.9 μmol·g^?1·h^?1), whereas in the dark the rates fluctuated around 0.0–11.1 μmol·g^?1·h^?1 throughout the whole incubation time (7 h). The soluble sugar content of Z. noltei leaves increased significantly with both ammonium and nitrate incubations in the light, indicating the metabolic outcome of photosynthesis. In the dark, there was no significant variation in either the soluble sugar or in the starch content of leaves, rhizomes or roots in either the ammonium or nitrate incubations. However, the total starch content of plants decreased at night whereas the total soluble sugars increased, suggesting a process of starch catabolism to generate energy with the consequent production of smaller monosaccharide products. The starch content of rhizomes decreased significantly during the light incubations with nitrate but not with ammonium. These results suggest that carbohydrate mobilization is necessary for Z. noltei to account for extra energetic costs needed for the uptake and assimilation of nitrate. Furthermore, our results suggest that nitrate uptake, at least during the day, requires the mobilization of starch whereas the uptake of ammonium does not.     

Bioenergetics of parental investment in two polychaete species with contrasting reproductive strategies: The planktotrophic Boccardia chilensis and the poecilogonic Boccardia wellingtonensis (Spionidae)

The level of parental investment for larval nutrition may determine the life cycle in marine invertebrate species laying egg masses or capsules, where the food available for enclosed individuals would determine time and developmental stage of hatching. Most species show a unique type of larval development. However, few species are poecilogonous and combine more than one development type. Poecilogony, although scarcely studied, allows comparing different patterns of parental reproductive investment, without the phylogenetic effect of the species ancestral modes of development (phylogenetic inertia), to help to understand the factors determining life strategy evolution in marine invertebrates. The poecilogonous polychaete worm Boccardia wellingtonensis encapsulates and incubates its offspring, which then hatches as either planktotrophic larvae or benthic juveniles; while Boccardia chilensis shows a non-poecilogonous reproductive type, producing only planktotrophic larvae. In this work, we estimated the bioenergetic and biochemical composition of brooding and non-brooding females of B. wellingtonensis and B. chilensis to compare the costs of reproduction in these two species. Results showed that glucose, protein, lipid, and energy content were significantly higher in non-brooding than in brooding females of B. wellingtonensis; but also contained significantly more glucose, protein, and lipid than females of B. chilensis (in absolute and relative dry weight values). The poecilogonous species showed higher energy content previous to laying offspring. Our results support the idea that the evolution of a certain reproductive and life history traits in marine invertebrates is related to adaptations in the female's reproductive investment.