The Mineral Adsorption and The Application of a Metamorphic Felsic Rock as Aggregate in Asphalt Pavements

Geotechnical and Geological Engineering - The aggregates consist approximately 85% of the total volume in asphalts pavements, and their properties influence directly their behavior. Therefore, it...     

Source constraints for the young basaltic rocks from the northernmost end of Cappadocian region,Turkey: Melting evidence from peridotite and pyroxenite source domains

Widespread magmatic activity developed in the Middle Miocene in the Cappadocian Region of Central Anatolia in Turkey. Despite several previous studies that focus on the geochemical features of the magmatic rocks, the source components and development of melting conditions are still a matter of debate.Recent basaltic rocks from Karaburna and Gül?ehir (1228 and 96 Ka, respectively, Dogan, 2011) are considered as a part of the Central Anatolian Volcanic Province, situated at the northernmost end of the Cappadocian Region. These lavas have similar large ion lithophile (LIL) (except Rb) and high field strength (HFS) element abundances, however, Karaburna samples are more enriched in HFS elements, and both of the rocks suites reflect HFS depletions relative to the OIB signature.Karaburna and Gül?ehir basalts have low Nb/La (0.45–0.5; 0.35–0.5), Nb/Th (2.75–4.61; 1.26–2.85) values, respectively, suggesting contributions from crustal sources, whereas Zr/Ba ratios of these samples range between 0.32–0.93 and 0.4–0.88 and imply that these rocks appear to be derived from asthenospheric sources. These incompatible element ratios can be attributed to either different geochemical processes, or are related to melting from different source component(s).The ambient mantle source of the Cappadocian region appears to be consistent with spinel peridotite, but this domain is not solely satisfactory to represent the melting conditions in the light of new elemental data. Values of Tb/Yb(N) and Zn/Fe provide new constraints suggesting the magmas were generated from the asthenosphere. Tb/Yb(N) ratio separates garnet – spinel transition Tb/Yb_(N) (>1.8) and Zn/Fe ratio displays separation between the peridotite-derived (Zn/Fe <12) and pyroxenite-derived (13?20) melts.A melting model based on REE ratios and Zn/Fe, Co/Fe, Tb/Yb(N) values indicates that basaltic rocks were not derived from a single source component (peridotite). Instead, those values suggest substantial melting contributions from a pyroxenite source domain, which has not been discussed as a source component in previous studies. Melts, from both of the source domains, with the result of asthenospheric upwelling linked to the downgoing Aegean and Cyprean slabs, are distinct from the alkaline character frequently observed as the final products of recent volcanic activity in the Cappadocian region and also explains the different trace element variations observed in such a small scale.     

Nonparametric analysis of high wind speed data

In this paper, nonparametric curve estimation methods are applied to analyze time series of wind speeds, focusing on the extreme events exceeding a chosen threshold. Classical parametric statistical approaches in this context consist in fitting a generalized Pareto distribution (GPD) to the tail of the empirical cumulative distribution, using maximum likelihood or the method of the moments to estimate the parameters of this distribution. Additionally, confidence intervals are usually computed to assess the uncertainty of the estimates. Nonparametric methods to estimate directly some quantities of interest, such as the probability of exceedance, the quantiles or return levels, or the return periods, are proposed. Moreover, bootstrap techniques are used to develop pointwise and simultaneous confidence intervals for these functions. The proposed models are applied to wind speed data in the Gulf Coast of US, comparing the results with those using the GPD approach, by means of a split-sample test. Results show that nonparametric methods are competitive with respect to the standard GPD approximations. The study is completed generating synthetic data sets and comparing the behavior of the parametric and the nonparametric estimates in this framework.     

Multifractal analysis of the rainfall time distribution on the metropolitan area of Barcelona (Spain)

In most of the studies on scale properties in the rainfall process, multifractal behavior has been investigated without taking into account the different rain generation mechanisms involved. However, it is known that rain processes are related to certain scales, determined by climatological characteristics as well as regional and local meteorological features. One of the implications derived from these correspondences is the possibility that the multifractal parameters of the rainfall could depend on the dominant precipitation generation mechanism. Fractal analysis techniques have been applied in this work to rainfall data recorded in the metropolitan area of Barcelona in the period 1994–2001, as well as to a selection of synoptic rainfall events registered in the same city in the period 1927–1992. The multifractal parameters obtained have been significantly different in each case probably showing the influence of the rain generation mechanisms involved. This influence has been revealed also in the analysis of the effects of seasonality on the multifractal behavior of rainfall in Barcelona.     

Tectono-metamorphic evolution of the Karakorum Metamorphic complex (Dassu–Askole area, NE Pakistan): exhumation of mid-crustal HT–MP gneisses in a convergent context

The South Karakorum margin, east of the Himalayan syntaxis, consist of an E–W elongated zone of young (10–3 Ma) high‐grade metamorphic rocks (M2) and related migmatitic domes. This late tectono‐metamorphic event post‐dates the Palaeogene (55–37 Ma) phase of thickening of the belt featured by NW–SE structures and associated M1 amphibolite facies metamorphism (0.7 GPa, 700 °C). This M2 metamorphism is characterised by low‐pressure, high‐temperature conditions coeval with migmatite formation in response to a thermal increase of c. 150 °C compared to M1, culminating at a temperature of c. 770 °C and a pressure of 0.5–0.6 GPa. Rapid exhumation of migmatitic domes, at a rate of 5 mm yr^?1, was accommodated by vertical extrusion, in the core of E–W crustal‐scale folds. These crustal‐scale folds formed in response to N–S syn‐collisional shortening and were enhanced by thermal weakening of the migmatised continental crust. M2 metamorphism is spatially and temporarily associated with granitoids showing a mantle affinity, firmly suggesting that this could be the advective heat source for the granite and syenite generation and the subsequent migmatisation of the mid‐crustal level. Such relationships between a mantle‐related magmatism and a high‐temperature metamorphism in a convergent shortening context are suggestive of the breakoff of the subducted Indian slab since 20 Ma.     

Feature: Geology of the bridges of the Dorset Stour

Famously, geology is on our doorstep, and an understanding of the geology of everyday things helps us communicate to those for whom it is a closed subject. The stone bridges of the River Stour from Stourhead to Christchurch in southern England are a topic worthy of study and rewarding as an example of the variety of the geology of this part of England.     

Diffusion in momentum space as a picture of second-order Fermi acceleration

Energetic particles in a turbulent medium can be subject to second-order Fermi acceleration due to scattering on moving plasma waves. This mechanism leads to growing particle momentum dispersion and, at the same time, increases the mean particle energy. In the most frequently met situations both processes can be represented by a single momentum diffusion term in the particle kinetic equation. In the present paper we discuss the conditions allowing the additional term for regular acceleration to arise. For forward-backward asymmetric scattering centres, besides the diffusive term one should explicitly consider the regular acceleration term in momentum space, which can consist of the first-order (∝ V), as well as the second-order (∝ V²) part in the wave velocity V. We derive the condition for the scattering probability in the wave rest frame requied for vanishing the regular acceleration term and provide a simple mechanical example illustrating the theoretical concepts. Finally, we address its possible role in cosmic ray acceleration processes.     

Survivorship of coral juveniles in a fish farm environment

Intensive fish farming is an emerging coastal activity that can potentially enhance sedimentation and promote eutrophication in fringing coral reefs. Here, we investigate the effect of fish farm effluent on the juvenile survivorship of the reef-building coral Seriatopora caliendrum. One-month old juvenile corals (on terracotta tiles) were deployed in fish farm and reference (reef) sites in Bolinao, the Philippines at a depth of 2m. After forty days, no survivor was recovered in the fish farm, while survivorship was low (11%) in the reference site, with the survivors' growth rate at 3.3polypsmo(-1) or 1.3mm(2)mo(-1). The fish farm deployed tiles were covered with muddy sediment and were colonized by barnacles, whereas those in the reference site were overgrown by a short stand of filamentous macroalgae. Environmental monitoring revealed higher nutrient levels (ammonia and phosphate), sedimentation rate, and organic matter flux, as well as diminished water transparency and dissolved oxygen levels in the fish farm compared to the reference site. Hence, intensive fish farming offers a suite of physical, chemical and biological modifications of the coastal marine environment which have a detrimental effect on the survivorship of coral juveniles.