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This paper describes a model for the prediction of sinkhole collapse for two-dimensional and axisymmetric conditions. The model explains the arching effect on the threshold of collapse by a catenary arch or dome that tries to redirect the self-weight of the unstable soil to the adjacent stable mass. The collapse mechanism considers the vertical displacement of this unstable soil mass through vertical slip planes. An adapted Krynine's construction is used for predicting Mohr–Coulomb failure conditions on the base of the catenary arches for saturated or dry conditions, whereas a simple modification is proposed for unsaturated conditions. Upward growth of sinkholes is also discussed on the basis of the model described, as well as the dependency of the stability of arches on oscillations of the water level. Some case studies and experimental evidence are presented for evaluation and application of the proposed model. It is shown that the catenary arch assumption is an efficient but simple approach for the prediction of sinkhole growth and collapse.

The study of the pre-Mesozoic geological history of NE Mexico offers the opportunity to reconstruct the processes that occurred at the NW margin of Gondwana. The Huizachal–Peregrina Anticlinorium, which is located west of Ciudad Victoria (Tamaulipas) is a regional structure produced during the Cretaceous–Palaeogene Laramide Orogeny. Its eroded core exposes Precambrian and Palaeozoic units that together comprise the Sierra Madre Oriental basement. These units are the Neoproterozoic metamorphic Novillo Complex, the Ordovician Peregrina Tonalite, the metamorphic Pennsylvanian Granjeno Complex, and the sedimentary Silurian–Permian Tamatan Group. Aserradero Rhyolite belongs to the Tamatan Group, occurring between the siliciclastic deposits of the Early Mississippian Vicente Guerrero and the Pennsylvanian Del Monte Formations. The studied rhyolites display geochemical characteristics corresponding to high-K, low-Sr, and S-type granitoid rocks that may have been produced by upper-crustal anatexis from a source similar to that of the Novillo Complex. New LA-ICP-MS U–Pb geochronological analysis on zircons separated from the Aserradero Rhyolite yielded Early to Middle Mississippian crystallisation ages of 347.8 ± 2.7 Ma and 340.7 ± 3.6 Ma, confirming that this acidic unit is in its original stratigraphic position despite the pervasive deformation of the Tamatan Group. Based on the correlation with other Carboniferous–Early Permian magmatic complexes in Mexico and Central America, it is suggested that the Aserradero Rhyolite represents an early stage of a precollisional Carboniferous–Permian peri-Gondwanan arc, occurring also in the Las Delicias, Oaxaquia, the Acatlan Complex, the Maya Block, as well as in the buried crystalline basement along the Western Gulf of Mexico. The assembly of the Precambrian and Palaeozoic basement units from the Huizachal–Peregrina Anticlinorium were integrated with the Ciudad Victoria Block, which was dismembered from Oaxaquia and their peripheral units during the Upper-Jurassic Gulf of Mexico opening.

This article proposes an approach to ensure consistency between constitutive formulations used in double-porosity models when the macrostructural void ratio, eM, is very small. These formulations model processes of different physical natures and therefore are usually presented independently, in which case an additive decomposition is assumed, and they calculate the total strain of the system as the sum of the strains caused by each process. This independence means that when eM is reduced, the contributions considered are not always consistent. To solve this problem, soil stiffness in the proposed approach is increased when eM is reduced, and at the same time the effect on strain by macrostructural processes not linked to changes in stress is reduced. To simulate the flow, it is assumed that there is always a minimum operating value of eM that controls mass transport. This approach was applied to a practical case, and confirmed that when the effect of the stress state on microstructure behavior was taken into account, the conceptual framework initially proposed for non-negligible eM values was satisfactorily extended., Este artículo propone un enfoque para asegurar la consistencia entre las formulaciones constitutivas utilizadas en los modelos de doble porosidad cuando la relación de vacío macroestructural , e M , es muy pequeña. Estas formulaciones modelan procesos de diferente naturaleza física y por lo tanto se suelen presentar de forma independiente, en cuyo caso se supone una descomposición aditiva, y calculan la deformación total del sistema como la suma de las deformaciones provocadas por cada proceso. Esta independencia hace que cuando e M se reduce, las contribuciones consideradas no siempre son consistentes. Para resolver este problema, la rigidez del suelo en el enfoque propuesto se incrementa cuando e Mse reduce, y al mismo tiempo se reduce el efecto sobre la deformación por procesos macroestructurales no vinculados a cambios en la tensión. Para simular el flujo, se supone que siempre hay un valor mínimo de operación de e M que controla el transporte masivo. Este enfoque se aplicó a un caso práctico y confirmó que cuando se tuvo en cuenta el efecto del estado tensional sobre el comportamiento de la microestructura, el marco conceptual propuesto inicialmente para valores de e M no despreciables se amplió satisfactoriamente.

The temperature effect on the microstructure deformability of compacted bentonites was assessed using a Clausius-Clapeyron type equation. To this end, vapor adsorption data obtained at different temperatures under low water content conditions was used, identifying changes in the microstructural water with changes in the microstructural void volume. The formulation proposed allows for an extension of the 2D-models used in macroscopic double-porosity approaches to a 3D surface in which temperature is explicitly considered. The results obtained were encouraging, fitting the experimental data highly satisfactorily. Therefore, the approach proposed in this study can be a key tool for characterizing the nonisothermal behavior of compacted bentonites., El efecto de la temperatura sobre la deformabilidad de la microestructura de las bentonitas compactadas se evaluó mediante una ecuación tipo Clausius-Clapeyron. Para ello, se utilizaron datos de adsorción de vapor obtenidos a diferentes temperaturas en condiciones de bajo contenido de agua, identificando cambios en el agua microestructural con cambios en el volumen vacío microestructural. La formulación propuesta permite una extensión de los modelos 2D utilizados en los enfoques macroscópicos de doble porosidad a una superficie 3D en la que se considera explícitamente la temperatura. Los resultados obtenidos fueron alentadores, ajustando muy satisfactoriamente los datos experimentales. Por lo tanto, el enfoque propuesto en este estudio puede ser una herramienta clave para caracterizar el comportamiento no isotérmico de las bentonitas compactadas.

The Huizachal–Peregrina Anticlinorium basement of the Sierra Madre Oriental in north-eastern (NE) Mexico comprises a wide variety of Precambrian and Paleozoic units. A granitic unit, described in this work as the Peregrina Tonalite (PTo), intruded the Neoproterozoic Novillo Gneiss, which is the northernmost expression of the Oaxaquia microcontinent. In contrast, the PTo’s contact with the Carboniferous Granjeno Schist is tectonic along vertical faults with a strike-slip component. This Paleozoic lithodeme is part of the Granjeno–Acatlan Belt. The PTo has been described as an orphaned block associated with an enigmatic Carboniferous magmatic arc located along the north-western (NW) margin of Gondwana. In this study, new U–Pb LA–ICP–MS data from PTo zircons included a youngest Late Ordovician (Katian stage) population at 448.8 ± 2.9 Ma, interpreted as the crystallisation age, and an oldest Grenvillian population interpreted as the potential age of its protolith. Additionally, major and trace element concentrations and ratios indicate a link to a continental arc that developed along the NW margin of Gondwana. Given this proposed arc’s age and position, a comprehensive model for the development of the NE Mexican basement without the involvement of exotic or orphaned terranes is now proposed. The PTo outcropping near Ciudad Victoria, Tamaulipas, is interpreted to be part of a previously unreported magmatic arc in NE Mexico established during the Late Ordovician, herein described as the Peregrina–Mochonian Orogeny. It represents an extension of the South American Famatinian arc into Mexico.

From samples of the Paleozoic Tamatan Group (Huizachal-Peregrina Anticlinorium, Tamaulipas, Mexico), petrographic (qualitative and modal) and geochemical analyses (major, trace, and rare earth elements) were conducted. The first U-Pb geochronological data on detrital zircons of the Tamatan Group were generated using four samples. The data presented here contains a broad overview of photomicrography, recalculated modal point-count data, raw geochemical data, and simple statistics of selected geochemical parameters. The data presented in this article are interpreted and discussed in the research article titled "Provenance and tectonic setting of the Tamatan Paleozoic sequence, NE Mexico: Implications for the closure of the Rheic Ocean at the northwestern part of Gondwana" [1].

Thermal load imposed on the ground by the foundations of some singular buildings may produce variations in geochemistry conditions. In soils containing soluble salts, such as gypsum, their dissolution/precipitation rates may be modified, triggering ground settlement as well as angular distortion of building foundations. This paper examines these processes for the case of the Central Storage Facility for high-level radioactive waste planned in Spain. This facility would impose a thermal load over a long period of time due to the disposal of spent nuclear fuel. A numerical model, including the equations for describing the dissolution/precipitation process, as well as the hydrogeological, thermal, chemical, and geomechanical changes in the ground caused by the construction and operation of the facilities, is proposed. The model focuses on the response of the building foundation under different hypothesis of thermal loading underneath the building. Comsol Multiphysics software was used for solving the resulting partial differential equations by the finite element method. This analysis concludes that moderate thermal loading of the ground would develop in the Case Study, with negligible mechanical effect on the foundation., La carga térmica impuesta al suelo por los cimientos de algunos edificios singulares puede producir variaciones en las condiciones geoquímicas . En suelos que contienen sales solubles, como el yeso , sus tasas de disolución/precipitación pueden modificarse, provocando asentamientos del suelo y distorsión angular de los cimientos de los edificios. Este artículo examina estos procesos para el caso de la Instalación Central de Almacenamiento de residuos radiactivos de alta actividad.prevista en España. Esta instalación impondría una carga térmica durante un largo período de tiempo debido a la eliminación del combustible nuclear gastado. Se propone un modelo numérico que incluye las ecuaciones para describir el proceso de disolución/precipitación, así como los cambios hidrogeológicos, térmicos, químicos y geomecánicos en el suelo provocados por la construcción y operación de las instalaciones. El modelo se centra en la respuesta de los cimientos del edificio bajo diferentes hipótesis de carga térmica debajo del edificio. Se utilizó el software Comsol Multiphysics para resolver las ecuaciones diferenciales parciales resultantes mediante el método de elementos finitos. Este análisis concluye que se desarrollaría una carga térmica moderada del suelo en el caso de estudio, con un efecto mecánico insignificante en la cimentación.

[ES] La modelación de las aguas subterránea es una herramienta muy potente para la evaluación de los acuíferos fracturados. En este trabajo, se construyó el modelo matemático del acuífero de la parte alta de la quebrada Huamancute, Ayacucho-Perú con la finalidad de comprender el comportamiento de las aguas subterráneas en el medio fisurado. En una primera instancia se desarrolló el modelo hidrogeológico conceptual, en el cual se tuvo en cuenta toda la información recaba de geología, hidrología, edafología y climatología; después se implementó el modelo numérico con la ayuda del código MODFLOW. El modelo conceptual hidrogeológico consistió en la identificación de las masas de agua de la zona de estudio, la construcción del modelo geológico y la estimación de la recarga al acuífero. El modelo geológico está formado por tres unidades hidrogeológicas, el depósito cuaternario es la capa más superficial, la intermedia es la roca fracturada y última es la denominada como roca. Dicho modelo se construyó en base a la geológica regional, a las mediciones de conductividades hidráulicas, y a los datos obtenidos de los veintiséis sondajes eléctricos verticales y de las treinta y nueve perforaciones. El área de estudio no contaba con información meteorológica, por lo que se estimaron los valores de la precipitación y de la temperatura, mediante el uso de la técnica geoestadística del cokrigeado colocalizado. Calculándose que la precipitación y la temperatura media anual es de 476.9 mm/año y de 10.5°C, respectivamente. El modelo hidrológico consistió en la estimación de la evapotranspiración potencial, la infiltración y la recarga; la primera variable se calculó mediante el método de Hargreaves y se obtuvo un valor medio de 1 252.7 mm/año; la segunda se estimó mediante el modelo número de curva y su valor promedio fue de 515.0 mm/año; mientras que la última se estimó mediante balances hidrometeorológicos, cuyo valor medio fue de 97.0 mm/año En este estudio se simuló tanto en estado estacionario como en transitorio, tomando para este último un paso de tiempo mensual. El río Huamancute se comporta como ganador, ya que la cantidad de agua que recibe del acuífero es mucho mayor a la que él le transfiere; mientras que los otros dos ríos, Laguiña y Quellopata, actúan como perdedores. La laguna Chiquito Parinacocha dona al acuífero un volumen medio de agua de 2.1 103 m3/año. Asimismo se tiene que en el área de estudio, el valor de la recarga media anual es de 5.8 104 m3/año. Por último se calculó que los bofedales extraen del acuífero un caudal promedio de 3.2 104 m3/año. En el estado transitorio se logró que el modelo reprodujera la variabilidad temporal de los caudales que el acuífero entrega a los ríos. Durante los meses que existe recarga, el flujo que acuífero transfiere al río Huamancute es de 56.0 l/s, mientras que en los otros ríos dicho caudal es de 10.0 l/s, aproximadamente. La mayor salida de agua del sistema es hacia los ríos. Asimismo, cuando existe recarga, la mayor parte del agua que ingresa por esta variable es almacenada en las dos primeras capas del acuífero, principalmente por la acción del almacenamiento específico. Se concluyó, que los cálculos de la recarga son mucho más precisas si se utiliza datos meteorológicos diarios, en caso de no contar con esta información, la mejor opción para dichas estimaciones es el cokrigeado colocalizado; y que los modelo numéricos en roca fisurada pueden ser calibrados mediante el método de prueba y error., [EN] Groundwater modeling is a very powerful tool for evaluating fractured aquifers. In this study, it was constructed the mathematical model of the aquifer in the upper part of the Huamancute stream, Ayacucho-Peru, in order to understand the behavior of groundwater in the fractured medium. In the first instance, it was developed the conceptual hydrogeological model, it was taken into account all the information gathered from geology, hydrology, edaphology and climatology; then, it was implemented the numerical model with the help of the MODFLOW code. The hydrogeological conceptual model consisted of the identification of the water masses in the study area, the construction of the geological model and the estimation of the recharge to the aquifer. The geological model is made up of three hydrogeological units, the quaternary deposit is the most superficial layer, the intermediate one is the fractured rock and the last one is called rock. Model was built based on regional geology, measurements of hydraulic conductivities, and data obtained from the twenty-six vertical electrical sounding and from the thirty-nine perforations. The study area did not have meteorological information, so precipitation and temperature values were estimated, using the geostatistical technique of collocated cokriging. Calculating that the annual average precipitation and temperature is 476.9 mm / year and 10.5 ° C, respectively. The hydrological model consisted in the estimating potential evapotranspiration, infiltration and recharge; The first variable was calculated using the Hargreaves method and it was obtained a mean value of 1 252.7 mm / year; the second was estimated using the curve number model and its average value was 515.0 mm / year; while the latter was estimated through hydrometeorological balances, whose average value was 97.0 mm / year. In this study, the model was simulated in steady and transient state, for the latter took a monthly time step. The Huamancute River behaves as the winner, since the amount of water it receives from the aquifer is much greater than that which it transfers; while the other two rivers, Laguiña and Quellopata, act as losers. The Chiquito Parinacocha lagoon donates an average volume of water of 2.1 103 m3 / year to the aquifer. Likewise, in the study area, the value of the average annual recharge is 5.8 104 m3 / year. Finally, it was calculated that the wetlands extract an average flow of 3.2 104 m3 / year from the aquifer. In the transitory state, the model was able to reproduce the temporal variability of the flows that the aquifer gives to the rivers. During the months that there is recharge, the flow that the aquifer transfers to the Huamancute River is 56.0 l / s, while in the other rivers this flow is approximately 10.0 l / s. The largest outlet of water from the system is towards the rivers. Likewise, when there is recharge, most of the water that enters through this variable is stored in the first two layers of the aquifer, mainly due to the action of specific storage. It was concluded that the recharge calculations are much more accurate, if daily meteorological data are used. If this information is not available, the best option for these estimates is collocated cokriging; and that numerical models in fractured rock can be calibrated by trial and error., [CA] El modelatge de les aigües subterrània és una eina molt potent per a l'avaluació dels aqüífers fracturats. En aquest treball, es va construir el model matemàtic de l'aqüífer de la part alta de la feta fallida Huamancute, Ayacucho-el Perú amb la finalitat de comprendre el comportament de les aigües subterrànies en el mitjà fisurado. En una primera instància es va desenvolupar el model hidrogeològic conceptual, en el qual es va tindre en compte tota la informació recapta de geologia, hidrologia, edafologia i climatologia; després es va implementar el model numèric amb l'ajuda del codi MODFLOW. El model conceptual hidrogeològic va consistir en la identificació de les masses d'aigua de la zona d'estudi, la construcció del model geològic i l'estimació de la recàrrega a l'aqüífer. El model geològic està format per tres unitats hidrogeològiques, el depòsit quaternari és la capa més superficial, la intermèdia és la roca fracturada i última és la denominada com a roca. Aquest model es va construir sobre la base de la geològica regional, als mesuraments de conductivitats hidràuliques, i a les dades obtingudes dels vint-i-sis sondatges elèctrics verticals i de les trenta-nou perforacions. L'àrea d'estudi no comptava amb informació meteorològica, per la qual cosa es van estimar els valors de la precipitació i de la temperatura, mitjançant l'ús de la tècnica geoestadística del cokrigeado colocalizado. Calculant-se que la precipitació i la temperatura mitjana anual és de 476.9 mm/any i de 10.5 °C, respectivament. El model hidrològic va consistir en l'estimació de la evapotranspiración potencial, la infiltració i la recàrrega; la primera variable es va calcular mitjançant el mètode de Hargreaves i es va obtindre un valor mitjà d'1 252.7 mm/any; la segona es va estimar mitjançant el model número de corba i el seu valor mitjà va ser de 515.0 mm/any; mentre que l'última es va estimar mitjançant balanços hidrometeorológicos, el valor mitjà dels quals va ser de 97.0 mm/any En aquest estudi es va simular tant en estat estacionari com en transitori, prenent per a aquest últim un pas de temps mensual. El riu Huamancute es comporta com a guanyador, ja que la quantitat d'aigua que rep de l'aqüífer és molt major a la qual ell li transfereix; mentre que els altres dos rius, Laguiña i Quellopata, actuen com a perdedors. La llacuna Chiquito Parinacocha dona a l'aqüífer un volum mitjà d'aigua de 2.1 103 m³/any. Així mateix es té que en l'àrea d'estudi, el valor de la recàrrega mitjana anual és de 5.8 104 m³/any. Finalment es va calcular que els bofedales extrauen de l'aqüífer un cabal mitjà de 3.2 104 m³/any. En l'estat transitori es va aconseguir que el model reproduïra la variabilitat temporal dels cabals que l'aqüífer lliurament als rius. Durant els mesos que existeix recàrrega, el flux que aqüífer transfereix al riu Huamancute és de 56.0 l/s, mentre que en els altres rius aquest cabal és de 10.0 l/s, aproximadament. La major eixida d'aigua del sistema és cap als rius. Així mateix, quan existeix recàrrega, la major part de l'aigua que ingressa per aquesta variable és emmagatzemada en les dues primeres capes de l'aqüífer, principalment per l'acció de l'emmagatzematge específic. Es va concloure, que els càlculs de la recàrrega són molt més precises si s'utilitza dades meteorològiques diàries, en cas de no comptar amb aquesta informació, la millor opció per a aquestes estimacions és el cokrigeado colocalizado; i que els modele numèrics en roca fisurada poden ser calibrats mitjançant el mètode de prova i error.

The present work analyses the hydro-mechanical behaviour of bentonite pellet mixtures using a macroscopic overlapping continua approach based on a triple porosity model. Two macrostructural functional levels are considered (inter-pellet pore space and void space between the clay aggregates inside the pellets) as well as a microstructural level (corresponding to the space inside the aggregates). This triple porosity approach reveals that, when assuming a double porosity model, the intrinsic permeability, the tortuosity and the degree of saturation of the single macrostructural level under consideration are the average values of the state functions of the adopted triple porosity model, but are not state functions themselves. The analysis also illustrates that, when assuming the same liquid pressure for the two macrostructural levels of the triple porosity model, it is relatively easy to expand upon the calculation procedures initially developed for a double porosity model to include a triple porosity model. When evaluating the applicability of the model, quality results were obtained, comparable to those of a triple porosity model, for both open and closed bentonite pellet mixtures. The results are better than those obtained with a double porosity model, since the state functions have a stronger physic base when using a triple porosity approach. Encouraging results are also obtained when analysing the overall swelling of a bentonite block and a mixture of bentonite pellets, using the same parameters for both materials. Therefore, given its capacity for relatively simple incorporation in a double porosity models, the model offers an interesting tool for researchers working on improving the characterisation of bentonite pellet mixtures.

The upwelling cores on the Caribbean Colombian coasts are mainly located at the Peninsula de la Guajira and Cabo de la Aguja. We used monthly averaged Moderate Resolution Imaging Spectroradiometer (MODIS) sea surface temperature as the only information to build up a prediction model for the upwelling events. This comprised two steps: (i) the reduction of the complexity by means of the Karhunen&ndash, Lo&egrave, ve transform and (ii) a prediction model of time series. Two prediction models were considered: (a) a parametric autoregressive-moving average (ARMA) time series from the Box&ndash, Jenkins methodology and (b) a harmonic synthesis model. The harmonic synthesis also comprised of two steps: the maximum entropy spectral analysis and a least-squares harmonic analysis on the set of frequencies. The parametric ARMA time series model failed at the time of prediction with a very narrow range, and it was quite difficult to apply. The harmonic synthesis allowed prediction with a horizon of six months with a correlation of about 0.80. The results can be summarized using the time series of the weights of the different oscillation modes, their spatial structures with the nodal lines, and a high confidence model with a horizon of prediction of about four months.

This paper presents a simplified method for the study of the soil-structure interaction problem for isolated footings on soils subjected to water content-related volume changes. The method is based on the 2D modelling of thermo-hydro-mechanical processes occurring in the soil and the soil–atmosphere interface, the calculation of the soil-footing system stiffness and the modelling of the structure. The idealization of soil-structure interaction from an equivalent springs model, obtained from the above characteristics, allows the movements changes in time of the foundations to be obtained. These in turn can be used for evaluation of building damage related to angular distortion among foundations.

The Precambrian metamorphic basement exposed in the eroded core of the Huizachal-Peregrina Anticlinorium (Cd. Victoria, Mexico) is described in this contribution as Novillo Metamorphic Complex (NMC). Based on field relations, modal content, whole rock geochemistry and Nd-isotopic ratios is possible to recognize two major units: (a) Metaigneous Unit (MIU) and (b) Metasedimentary Unit (MSU). The MIU is subdivided into the Old Suite, constituted by (a) felsic gneisses from Novillo canyon, (b) felsic gneisses from Peregrina canyon, (c) metagranites, (d) mafic gneisses, and (d) migmatites; and the AMCG Suite, composed by (a) meta-anorthosites, (b) metagranite-gabbro intercalations, (c) metacharnockites, (d) garnet-rich metaferrodiorite dykes, and (e) metanelsonites. The MSU is represented by (a) meta-arkose – amphibolite intercalations and (b) calcsilicate marbles. Tectonic discrimination diagrams based on linear discriminant analysis of natural logarithm transformed ratios of elements show an island arc tectonic setting for the MIU. Nd isotopic ratios show crustal residence TDM ages of 1.49–1.44 Ga for the Old Suite (2 samples) and 1.63–1.33 Ga for the AMCG Suite (7 samples). The MSU have TDM between 1.39 a 1.25 Ga (3 samples) that support the interpretation that the protoliths were possibly deposited in a basin with sediment input from the younger MIU members. These deposits were later thrusted over MIU rather than intruded, and together metamorphosed under granulite facies conditions by the ca. 1.0 Ga Zapotecan orogeny. However, since the metaferrodioritic bodies cut discordantly the meta-anorthosites fabric, they represent a younger tectonothermal event, not yet described for the NMC.

The geochemistry of the metavolcanic rocks from the Granjeno Schist in northeastern Mexico indicates an origin in different tectonic environments: mid-ocean ridge and ocean island. High ratios of Hf/Th and Th/Nb (4.4-14 and 0.08-0.15), low ratios of LaN/YbN and LaN/SmN (0.74-1.7 and 0.60-1.4) and depleted LREE patterns in metabasalt display mid-ocean ridge characteristics. In contrast, the pattern of trace-element ratios and REEs in metabasalt and metapillow lava 60km to the west indicates a magma source with ocean-island basalt characteristics. Both areas were metamorphosed during the Late Carboniferous (300±4Ma). Estimated metamorphic conditions deduced from white mica and chlorite compositions, distinguish greenschist facies (350°C and 4kbar) for the mid-ocean ridge basalt, and prehnite-pumpellyite facies (250°C and 2.5kbar) for the ocean-island-type basalt. This metamorphism took place at an active continental margin during Pennsylvanian time. Our new tectonic model, which differs from earlier models, suggests that the origin of the Granjeno Schist is related to a subduction zone located at the western margin of Pangaea, active after Laurentia-Gondwana collision. (Less)

The Granjeno Schist is a meta-volcanosedimentary upper Paleozoic complex in northeastern Mexico. We suggest different tectonic settings for metamorphism of its serpentinite and talc-bearing rocks based on petrographic and geochemical compositions. According to the REE ratios (LaN/YbN = 0.51–20.0 and LaN/SmN = 0.72–9.1) and the enrichment in the highly incompatible elements Cs (0.1 ppm), U (2.8 ppm), and Zr (60 ppm) as well as depletion in Ba (1 – 15 ppm), Sr (1–184ppm),Pb(0.1–14ppm),andCe(0.1–1.9ppm)the rocks have mid-ocean ridge and subduction zones characteristics.TheserpentinitecontainsAl-chromite,ferrian chromiteandmagnetite.TheAl-chromiteischaracterized byCr#of0.48to0.55suggestingaMORBorigin,andCr#of 0.93 to 1.00 for the ferrian chromite indicates a prograde metamorphism.Weproposeatleasttwoserpentinization stagesoflithosphericmantlefortheultramaficrockofthe GranjenoSchist,(1)afirstinanocean-floorenvironment atsub-greenschisttogreenschistfaciesconditionsand(2) later a serpentinization phase related to the progressive replacement of spinel by ferrian chromite and magnetite atgreenschisttolowamphibolitefaciesconditionsduring regional metamorphism. The second serpentinization phase took place in an active continental margin during the Pennsylvanian. We propose that the origin of the ultramaficrocksisrelated toanobductionandaccretional eventatthewesternmarginofPangea. Keywords: ultramafic rocks; serpentinite; Granjeno Schist;northeasternMexico,Gondwana,Pangea

This article proposes a new plastification mechanism to model bentonite free swelling processes by using an elastoplastic approach. The formulation is based on an interaction function that defines the plastic macrostructural strains induced by microstructural effects. This term is defined as a function of the microstructural void ratio, and it establishes a direct connection between the destructuration of the micro- and macrostructures of the bentonite during the free swelling processes. The formulation proposed also includes a new approach to the calculation of the microstructural void ratio as well as a new method to describe the kinetic mass exchange between micro- and macrostructural water, considering that there may not be equilibrium between the two types of water. The model was used to analyse several free swelling tests and was found to yield satisfactory results.

A constitutive model of the volumetric behaviour of bentonite aggregates is proposed. The model is based on a state function to define the inter-aggregate (microstructural) void ratio and on a mass transfer function to calculate the mass exchange between macrostructural and microstructural water. Although both functions have been used previously for clay soils, their application beyond the range for which they were derived is proposed. To evaluate whether this extrapolation is valid, data on the swelling of individual bentonite aggregates are analysed. This novel aspect of this study is significant because it is not common to analyse microstructural data directly without introducing any hypothesis about the behaviour of the macrostructure. Despite the lack of a more intensive validation, which will be conducted when more experimental data become available, the results obtained have been satisfactory.

Sinkholes in karst areas disrupt transportation route serviceability causing significant direct and indirect economic losses and may lead to accidents involving fatalities. A quantitative procedure has been developed to identify the most suitable mitigation designs for a road recently built in an area with a very high probability of sinkhole occurrence. Installation of geogrids with different resistances to a variable number of road sections has been simulated taking into account the occurrence probability of sinkholes with different diameters in each section. The proposed methodology includes the following phases: (1) Development of a sinkhole hazard model that predicts the occurrence probability of sinkholes with different diameters in each 5 × 5 m pixel of the road. (2) Vulnerability appraisal of the road by means of stability analyses. (3) Risk assessment for the “without geogrid” and multiple “with geogrid” scenarios including direct and indirect economic losses, as well as expected number of fatalities. (4) Cost–benefit analysis to estimate the net benefit of the mitigation designs. (5) Acceptability analysis considering geogrid solutions based on cost-effectiveness, conventional (maximum acceptable rate of fatalities) and utility-based (maximum acceptable investment in mitigation to prevent fatalities) criteria. (6) Sensitivity analysis to evaluate the impact of the uncertainty of a set of parameters on the most critical results from the risk management perspective. The presented method could be easily adapted to other geohazards (e.g. shallow landslides, rock-falls, piping), different infrastructures (e.g. railways), as well as to other corrective measures (e.g. concrete slabs, catch fences, armoured roofs, steel meshes, barrier systems).

This article proposes a synthetic model to explain the cracking process observed in Santos Morcillo Lake, Ruidera Lakes Natural Park, central Spain. The model was obtained by means of a comprehensive review of the available data, supplemented with an electrical tomography survey and a field and laboratory investigation. The system’s structure has been condensed into a microscale model based on a sediment column connecting the crust of the lake bottom with the Mesozoic substrate. The deformation of both this column and the crust covering it allows for a consistent explanation of the behaviors observed. It also provides a simple reproduction of the crack opening data. Hence the model has been used to define guidelines for the safe use and management of this protected space.

This article presents the study conducted and the actions taken to stabilise the foundations of 25 low-rise (two/three-storey) buildings in Alcazar de San Juan (Ciudad Real, central Spain). Owing to the immediate attention required, it was decided that the study would focus on procuring a synthetic model that would be able to provide a satisfactory explanation for the tendency of the movements, overlooking the detailed model of each building. This analysis pointed out that the mobilisation was probably due to both the shrinkage caused by the existing trees during the dry-growing seasons, and to the loss of lateral confinement caused by the excavation of a service trench adjacent to the footings of the buildings. In keeping with this mechanism, stabilization was carried out by transplanting the trees growing near the damaged buildings and installing a line of piles to provide lateral support to the footings. The evolution of the damage was therefore stopped.

Tidal mills were the main industrial activity in the Bay of Cadiz for centuries. They were the last step in the production of salt and flour made by grinding grains. They were installed along the shallow channels, called “caños”, around the Bay, where the frictional and geometrical effects are very strong. The authors have analyzed the propagation of the semidiurnal tidal waves along the Caño de Sancti Petri and the available tidal power in the area. The ancient tidal mills were located where the available tidal potential energy is highest, which ensured productivity for grinding salt and wheat in ancient times. Some considerations about the possibility of installing tidal power plants in the Bay of Cadiz now are given, which show that it could be a real and renewal alternative source of energy for the area. Los molinos de marea fueron durante siglos la actividad industrial más importante de la Bahía de Cádiz. Eran, con la molienda, el último paso de la cadena de producción de la sal y los cereales. Estaban localizados en los canales largos y poco profundos de los alrededores de la Bahía de Cádiz, denominados “caños”. En ellos los efectos de fricción y geométricos tienen gran importancia. Los autores analizan la propagación de las ondas de marea semidiurnas a lo largo del Caño de Sancti Petri y la potencia de marea disponible en él. La localización de los molinos de marea antiguos corresponde a los lugares donde la energía potencial de la marea es máxima, asegurando, en aquel entonces, una alta producción en la molienda de sal y cereal. Se considera la posibilidad de explotar la energía de mareas industrialmente en términos de centrales mareomotrices, siendo una alternativa real como fuente de energía alternativa para la zona.

Alkaline magmas along the periphery of Sierra de San Carlos-Cruillas and Sierra de Tamaulipas (Eastern Alkaline Province, northeast Mexico) contain ultramafic xenoliths. Most of the host rocks are mafic (e.g., basalts, basanites, trachybasalts, phonotephrites), and have geochemical characteristics of nearly primary magmas generated in subcontinental zones (SiO2 = 42.6-48.4%, MgO = 6.3-11.2%, Mg# = 59.2-69.7). MORB-normalized patterns are similar to those displayed by extensionrelated mafic magmas. This hypothesis is supported by an enrichment in light REE ([La/Yb]N = 10.8-27.1; chondrite-normalized ratios) and the behavior of relatively immobile trace elements. Using a partial melting model for REE, the source for the mafic magmas apparently was in the garnet P-T stability field. On the other hand, peralkaline phonolites and tephriphonolites (SiO2 = 52.9-54.1%, MgO = 1.5-1.8%, Mg# = 33.1-39.8) also contain mantle xenoliths. These evolved magmas show MORB-normalized multi-element diagrams characterized by ...

The main sill of the Strait of Gibraltar (Camarinal Sill) is an area of very energetic internal wave activity. The highest amplitude internal wave is the well-known internal bore, generated at critical conditions over Camarinal Sill. A very energetic lee wave has recently been found and reported. This occurs in neap tides when favorable combination of the stratification, vertical profile of horizontal background velocity, and bottom topography determines its generation. When the lee wave is developed the manifestation of high-amplitude internal waves is observed at the sea surface as high-frequency chaotic oscillations, named boiling waters . We analyze the generation of the lee wave over the main sill of Gibraltar Strait on the basis of the data from a ship mounted ADCP, multi-probe CTD data taken during a survey carried out in November 1998, and the numerical solution of the Taylor–Goldstein equation for the prevailing hydraulic conditions previous to its generation. Stratification is computed from CTD data, and the tidal current prediction is made from the 2 years of ADCP hourly data at Camarinal Sill gathered during the Gibraltar Experiment 94-96. The main characteristic is that they happen during neap tides, and their magnitude is comparable to the internal bore generated during spring tides. The classical internal bore and the lee waves are different phenomena, and the presence of the latter is an indicator of minimum flow over Camarinal Sill. A prediction model for lee waves based on the tidal hydrodynamic conditions is also developed.