PHYSICAL IMPACTS OF CLIMATIC CHANGE ON DELTAIC COASTAL SYSTEMS (I): AN APPROACH

The evaluation of the impact of climate change on deltaic systems implies studying a multi-component system in which the complexity of links is high enough to present doing it as a whole. Because of this, it is a reasonable approach to study separately the behaviour of each element, to be afterwards linked into a general conceptual model for deltaic behaviour. Moreover, in the case of largely regulated deltas, the main impacts of climatic change will be marine-related since those related to the catchment areas will be severely damped by river regulation and management policies. This fact implies that coastal fringes may become the main frontier between the delta and climatic change effects. In this context, a methodology to study climatic change impacts on deltaic coastal fringes is here presented. It will be further developed on two companion papers dealing with the study of driving terms and coastal response. As coastal processes act at different time and space scales, determining the reference – initial – situation must be done taking into account the inherent system dynamics. It is thus unrealistic to characterize the initial stage as a static one. In order to avoid this simplistic approach, a comprehensive approach to the coastal system must be employed, with three different scales (long-term/large scale, medium term/scale and episodic).     

PHYSICAL IMPACTS OF CLIMATIC CHANGE ON DELTAIC COASTAL SYSTEMS (II): DRIVING TERMS

The evaluation of the impact of climatic change on deltaic coastal systems requires establishing a reference situation. As deltaic coastal zones are highly dynamic areas, it is necessary to define the reference situation as a function of their present evolutive stage. This implies characterizing coastal processes as a complex system defined by the links between driving or forcing terms and the coastal response at different temporal and spatial scales (long/large, medium and episodic scales). Starting from classical previous works on deltaic systems and including all available field and conceptual knowledge to properly consider present conditions (largely regulated rivers, subsidence, etc.) a detailed methodology to analyse forcing or driving agents at the three mentioned scales is presented. This methodology which developed the general approach presented in a companion paper, will be followed by a future paper focusing on the analysis of the coastal response.     

A Comparative Analysis of Pillar Design Methods and its Application to Marble Mines

Summary. The methods for designing pillars in underground mines are fundamentally based on empirical formulae that do not take into account the quality of the rock mass as an input parameter. This makes them difficult to apply in other types of ground that are different to those used to establish each empirical formula. To avoid this inconvenience, the present paper examines existing empirical formulae to then propose a modification of these formulae adjusting the resistance of the pillars on the basis of the RMR (Bieniawski’s Rock Mass Rating). The compression safety factor of the pillars is analyzed for each modified formula and a study is carried out of shear failure if planes of weakness exist in the pillars. Finally, the safety factors of the pillars in a marble mine situated in Alicante (Southern Spain) were calculated in order to validate the new formulae. From the results obtained, it is concluded that this new formulation determines the safety factor of pillars of the mine with greater reliability, provided that the pillars are isolated. At the same time, the introduction of the RMR in the formulae results in a better fit of the strength of each pillar to the characteristics of the rock mass.     

Das Erdstrom-Observatorium bei Nagycenk (Ungarn)

Zusammenfassung Im ersten Teil des Artikels werden — nach einem kurzen geschichtlichen Rückblick — die Anlage und die technischen Einrichtungen des im IGJ bei Nagycenk (Ungarn) errichteten tellurischen Observatoriums dargelegt. Der zweite Teil beschäftigt sich mit der Bearbeitung der Registrierungen. Wir wollen in erster Richtung die Verteilung der Variationen von verschiedenen Perioden untersuchen, und wir ordneten deshalb, teils auf Grund der Gegebenheiten der Registrierungen, hauptsächlich aber der Untersuchung bei verschiedenen Typen wegen, die Variationen in 5, bzw.9 Klassen ein. Ausserdem führen wir die tellurischen Äquivalenten der magnetischen Phenomena (Bay, Sturm, usw) und die Grundlagen deren Einteilung an. Die Publikationen über Karakteristiken und Graphikons zweccks Erkennung der Eigenschaften der Variationen werden wir von Zeit zu Zeit forsetzen.

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Summary In the first part of the article the writers — after a brief historical note — acquaint with the question of the location of the telluric observatory, established during the IGY near Nagycenk (Hungary) and with its technical arrangements. The second part presents the preparation of the records. It was chiefly the distribution of the different periodic variations in our mind, and this is why we included the variations, partly based on the given conditions of the recording, but in first line on the examination of periods of the different types in 5, respectively in 9 classes. Moreover, we specify the telluric equivalents of magnetic phenomena (bay, storm, etc.) and the basic principles of the classification. We shall report periodically on the characterics and graphs concerning the feature of the variations.

     

Poroelastic coefficients for anisotropic single and double porosity media

Acta Geotechnica - Closed-form expressions for poroelastic coefficients are derived for anisotropic materials exhibiting single and double porosity. A novel feature of the formulation is the use of...     

Seasonal changes in the biochemical composition of females and offspring of red squat lobster,Pleuroncodes monodon (Decapoda,Munididae), from the Southeastern Pacific

Pleuroncodes monodon is an important fishery resource and key species from the Southeastern Pacific. During its prolonged reproductive period (from February to December), ovigerous females are exposed to seasonal variation in environmental factors (e.g. temperature and food availability), with higher levels of these environmental parameters during summer and lower in winter, and must adjust their biochemistry to ensure their own survival and that of their embryos. The aim of this study was to analyse seasonal changes in the biochemical composition of ovigerous females and their eggs. The data show that the content of lipids, proteins and organic matter in the hepatopancreases of females was significantly higher in winter than in summer. Similarly, the lipid content of the eggs was significantly higher in winter than in summer, yet the protein content of the eggs had the opposite pattern with greater values found in summer. Consistent with the ‘reproductive energetic model’, the initial and final energy produced by the hepatopancreas showed significant seasonal variations, whereas female investment in egg production (in absolute values) did not show significant seasonal differences. The seasonal differences observed in the biochemistry, organic matter and energy content of the female hepatopancreases may be related to the storage of energy for growth and reproduction. Furthermore, the seasonal variation in the content of lipids, proteins and energy in eggs is likely related to embryogenesis and larval hatching in function with environmental conditions. Seasonal variation in the biochemical composition of P. monodon has direct effects on the marine food web and also upon fisheries.     

Current status of coral takeover by an encrusting excavating sponge in a Caribbean reef

On Caribbean reefs, the excavating sponge Cliona tenuis opportunistically colonized dead skeletons of the elkhorn coral Acropora palmata after its massive die‐off in the 1980s. Further C. tenuis population increase occurred by colonization of other coral species, causing coral tissue death through undermining of live tissue and lateral growth. To follow up on a previous (2001) characterization of the abundance and size structure of C. tenuis at Islas del Rosario (Colombia), these factors were again estimated in 2014, along with its substratum utilization. The fate of sponge individuals colonizing massive coral colonies marked in 2001–2004 was also followed. By 2014 C. tenuis was still disproportionally occupying dead A. palmata branches, but its abundance and density, and the cover of other benthic elements, had not significantly changed over the 13‐year period, suggesting that a stasis has been reached. Cliona tenuis was thus initially favored in the 1980s, but substratum monopolization did not occur. From 2001 to 2014, small individuals increased in number and very large ones decreased, suggesting not only that new recruitment is occurring, but also that larger sponges are shrinking or fragmenting. Marked sponges continued killing corals over the first few years, but over longer times they retreated or died, allowing corals to resume upward growth. However, it could not be ascertained whether the sponge retreat was age‐related or the result of some environmental effect. The apparent preference for recently dead clean coral by larvae of C. tenuis and its current dynamics of recruitment, growth, fragmentation and mortality have stabilized its space occupation at Islas del Rosario.     

Geochemical Characterization of Magnetite and Geological Setting of the Iron Oxide ± Iron Silicate ± Iron Carbonate Rich Pb–Zn Sulfides from the La Unión and Mazarrón Stratabound Deposits (SE Spain)

From a mineralogical point of view the La Unión ore field (SE Spain) can be regarded as an oddity as some of its hydrothermal, stratabound type deposits display an extremely unusual paragenesis comprising magnetite ± greenalite ± minnesotaite ± siderite and galena ± sphalerite (IOSC – LZS). Recent mineralogical studies have shown that this paragenesis is also present at the neighboring Mazarrón ore field. These ore fields share a similar geologic setting, involving metamorphic and sedimentary rocks (Paleozoic s.l. to Permian) hosting late Miocene high‐K calc‐alkaline volcanic and subvolcanic rocks. The latter have andesitic to dacitic composition, and triggered hydrothermal activity and ore deposition. This study discusses the detailed mineral chemistry of magnetite samples from Mazarrón and La Unión and provides some hints for the origin of the IOSC – LZS paragenesis. We performed electron microprobe (EPMA) analyses in magnetite samples from La Unión and Mazarrón to determine the contents of minor and trace elements (Zn, Ni, Mn, Cr, V, K, Ca, Ti, Al, Si, Mg). Given that some results fell below the detection limit for the EPMA instrumental conditions we used robust regression on order statistics (robust ROS), with the NADA package in R to deal with these data sets. The Ca + Al + Mn contents in magnetites from San Cristóbal and Emilia are equivalent to the mean contents of those of IOCG, Kiruna, BIF, Cu porphyry, skarn, VMS, hydrothermal and clastic Pb–Zn deposits, but they are low in Ti + V and Ni + Cr. The principal components analysis indicates that Zn, Ni, Cr, V, K, Ca, Ti, and Mg are roughly collinear, therefore correlated, being also independent from Fe. Besides, the function discriminant analysis of data shows that the magnetites from Emilia and San Cristóbal cluster in differentiated groups, thus probably reflecting some differences related to the distance to the magmatic source that triggered the hydrothermal system: proximal in the case of San Cristóbal and distal in Emilia.