Evidence of mud diapirism and coral colonies in the ionian sea (central mediterranean) from high resolution chirp sonar survey

A chirp sonar survey in the Ionian Sea investigated the Calabrian margin, the Calabrian accretionary wedge, the Taranto Trench and the Apulian foreland. Shallow tectonics structures have been related to deeper ones, recognised on CROP seismic profiles. The identified echo characters have been compared with those described in the modern literature and have been related to different kinds of sediments, on the basis of core samples. Based on echo character and morphology we have recognised: 1) A widespread presence of mounds, up to 50 m high, occurring on the Apulian plateau as isolated mounds in the deepest zones (1600-800 m) and in groups in the shallower ones (800-600 m); they have been interpreted as coral mounds, according to a recent discovery of living deep water coral colonies in this zone. 2) Some mud diapirs, isolated or in groups of two or three elements, widespread in the whole study area. In analogy of what has been observed on the Mediterranean Ridge, their presence suggests the activity of deep tectonic structures (thrusts and faults) and a reduced thickness (or absence) of Messinian evaporites in this part of the Ionian Sea

High-Resolution 3D FEM Stability Analysis of the Sabereebi Cave Monastery, Georgia

This study assesses the static stability of the artificial Sabereebi Cave Monastery southeast of Georgia's capital, Tbilisi. The cliff into which these Georgian-Orthodox caverns, chapels, and churches were carved consists of a five-layered sequence of weak sedimentary rock—all of which bear a considerable failure potential and, consequently, pose the challenge of preservation to geologists, engineers, and archaeologists. In the first part of this study, we present a strategy to process point cloud data from drone photogrammetry as well as from laser scanners acquired in- and outside the caves into high-resolution CAD objects that can be used for numerical modeling ranging from macro- to micro-scale. In the second part, we explore four distinct series of static elasto-plastic finite element stability models featuring different levels of detail, each of which focuses on specific geomechanical scenarios such as classic landsliding due to overburden, deformation of architectural features as a result of stress concentration, material response to weathering, and pillar failure due to vertical load. With this bipartite approach, the study serves as a comprehensive 3D stability assessment of the Sabereebi Cave Monastery on the one hand; on the other hand, the established procedure should serve as a pilot scheme, which could be adapted to different sites in the future combining non-invasive and relatively cost-efficient assessment methods, data processing and hazard estimation

Directional analysis of the variation of the weathering (micro)rate in calcarenites exposed to coastal semiarid climate

En este trabajo se propone una nueva metodología, basada en microtomografía de Rayos X y Análisis Digital de Imagen, para el cálculo de tasas de alteración de rocas a partir de breves periodos de exposición directa al ambiente. Se han estudiado dos rocas car bonatadas porosas (una calcarenita y una calcirrudita con porosidad media del 20%), expuestas durante un año a un clima Mediterráneo semiárido costero (Nueva Tabarca, Alicante). Las microtasas obtenidas indican una mayor velocidad de alteración en la calcirrudita (18.75 mm/ año) que en la calcarenita (9.13 mm/año). Esta variación se justifica por las diferencias en el sistema poroso de cada roca y su influencia en la efectividad de los procesos de alteración habituales en climas semiári dos costeros. Además, los resultados obtenidos validan la metodología planteada, la cual constituye un importante avance en el estudio de la velocidad de deterioro de materiales, permitiendo de una forma rápida y cuantitativa, analizar la vulnerabilidad de las rocas a determinados ambientes de exposiciónThis paper proposes a new methodology to calculate weathe ring rates of rocks after brief periods of direct exposure to the envi ronment. The methodology bases on X-Ray microtomography and Digital Image Analysis. Two porous carbonate rocks have been stu died: a calcarenite and a calcirrudite with an average porosity of 20%. They were exposed for one year to a coastal semiarid Mediterranean climate (Nueva Tabarca, Alicante; SE of Spain). The obtained microra tes indicate a higher weathering rate in calcirrudite (18.75 mm/year) than in calcarenite (9.13 mm/year). This variation is justified by the differences in the porous system of each rock and its influence on the effectiveness of the usual alteration processes acting on rocks exposed to coastal semiarid climates. In addition, obtained results validate the proposed methodology, which constitutes an important advance in the study of the weathering rates of materials. It allows a quick and quantitative way to analyse the vulnerability of rocks to specific expo sure environment

Ultrasonic and X-ray computed tomography characterization of progressive fracture damage in low-porous carbonate rocks

This paper studies the fracturing process in low-porous rocks during uniaxial compressive tests considering the original defects and the new mechanical cracks in the material. For this purpose, five different kinds of rocks have been chosen with carbonate mineralogy and low porosity (lower than 2%). The characterization of the fracture damage is carried out using three different techniques: ultrasounds, mercury porosimetry and X-ray computed tomography. The proposed methodology allows quantifying the evolution of the porous system as well as studying the location of new cracks in the rock samples. Intercrystalline porosity (the smallest pores with pore radius < 1 μm) shows a limited development during loading, disappearing rapidly from the porosimetry curves and it is directly related to the initial plastic behaviour in the stress–strain patterns. However, the biggest pores (corresponding to the cracks) suffer a continuous enlargement until the unstable propagation of fractures. The measured crack initiation stress varies between 0.25 σp and 0.50 σp for marbles and between 0.50 σp and 0.85 σp for micrite limestone. The unstable propagation of cracks is assumed to occur very close to the peak strength. Crack propagation through the sample is completely independent of pre-existing defects (porous bands, stylolites, fractures and veins). The ultrasonic response in the time-domain is less sensitive to the fracture damage than the frequency-domain. P-wave velocity increases during loading test until the beginning of the unstable crack propagation. This increase is higher for marbles (between 15% and 30% from initial vp values) and lower for micrite limestones (between 5% and 10%). When the mechanical cracks propagate unstably, the velocity stops to increase and decreases only when rock damage is very high. Frequency analysis of the ultrasonic signals shows clear changes during the loading process. The spectrum of treated waveforms shows two main frequency peaks centred at low (~ 20 kHz) and high (~ 35 kHz) values. When new fractures appear and grow the amplitude of the high-frequency peak decreases, while that of the low-frequency peak increases. Besides, a slight frequency shift is observed towards higher frequencies

Role of soil pore structure in water infiltration and CO2 exchange between the atmosphere and underground air in the vadose zone: A combined laboratory and field approach

The soils above caves represent a membrane that regulates the connection between the underground environment and the outside atmosphere. In this study, soils from two different field sites (Cueva de Altamira and Cueva del Rull in Spain) are investigated. Field results are analysed and linked to laboratory tests. Several laboratory experiments are performed to quantify CO2 diffusion coefficients and water infiltration rates in these soils under different degrees of soil water saturation and compaction. Tests confirm that the grain size distribution, organic matter content, mineral composition and water content of soils affect gas transport through the soil pore network. Both field and lab results reveal that Altamira soil has a coarser texture and therefore has higher CO2 diffusion coefficients, infiltration rates and hydraulic conductivity values than Rull soil. Rull soil contains a higher proportion of fine particles and organic matter, which explains the lower fluid transport coefficients. When soils are near saturation, fluid transport does not depend on the physical properties of soil but depends on the soil water content. In this state, liquid transport regulates the available space within the soil pores, which leads to a reduction in the gaseous diffusion coefficient of the soil. After rainfall episodes, the connection between the exterior atmosphere and underground cavities is hindered due to a rise in the soil water content, which is responsible for the closure of the overlying membrane. This study demonstrates that soil-produced CO2 reaches the underground atmosphere through diffusion processes that are controlled by the intrinsic properties of soil (porosity, grain size distribution, texture, mineralogy and organic matter content) and soil water content.This research was funded by the Spanish Ministry of Economy and Competitiveness projects CGL2011-25162 and CGL2013-43324-R and its programme Torres Quevedo (PTQ 13-06296). A pre-doctoral research fellowship (BES-2012-053468) was awarded to C. Pla for the project CGL2011-25162. Funding was also provided by the People Programme (Marie Curie Actions–Intra-European Fellowships, call 2013) of the European Union's Seventh Framework Programme (FP7/2007–2013) under the REA grant agreement n° 624204

Controlled source electromagnetic measurements offshore the Maltese Islands : implications for offshore freshened groundwater in a carbonate shelf

Carbonate lithologies host considerable quantities of the Earth’s freshwater resources and partially supply a significant amount of the global population with drinkable water. Although they comprise substantial amounts of the coastlines, it is not known if these carbonate lithologies can sustain freshened groundwater offshore, and if this can help meet future water demands in coastal regions. To date, predicting volumes of freshened groundwater within marine carbonates has been challenging. Here, we integrate controlled source electromagnetic profiles with seismic reflection and core log data to derive a lithological model for the eastern carbonate margin of the Maltese Islands, one of the most water-starved countries in the world. Electrical resistivity models are used to guide lithological inference where seismic data provide limited information due to the superimposed seafloor multiple. We show that resistivity values within the Upper Coralline and Globigerina Limestone formations exceed the measured resistivity of seawater-saturated core log samples by at least a factor of four. This could be indicative of offshore freshened groundwater that occupies the pore space of the low permeability limestone along the eastern Maltese shelf. To validate this observation without further ground-truthing data, we use extensive forward modelling to show that a similar resistivity footprint can be achieved by localized interbedded low-porosity or highly cemented units. However, the spatial extent of such units across the entire eastern Maltese margin is geologically improbable. This points to the occurrence of offshore freshened groundwater that was likely emplaced during the last sea-level lowstand.peer-reviewe

Electrical resistivity anomalies offshore a carbonate coastline : evidence for freshened groundwater?

Carbonate lithologies host considerable quantities of the Earth's freshwater resources and partially supply a quarter of the global population with drinkable water. In addition, carbonates constitute substantial amounts of the global coastlines, yet it is not known if and how they can sustain freshened groundwater offshore. Here, we use controlled-source electromagnetic, seismic reflection, and core sample data to derive a lithological model for the eastern margin of the Maltese Islands and identify four distinct resistivity anomalies within the Upper Coralline and Globigerina Limestone formations. The anomalies hosted in the former are likely associated with low porosities, whereas the anomaly within the latter is indicative of pore fluid freshening. Hydrogeological modeling suggests that freshened pore fluids, emplaced during sea-level lowstands and preserved in low permeability units, are potentially still found within carbonate shelves. However, resource potential is low due to its relict nature and low permeability host environment.peer-reviewe

RESCUhE Project: Cultural Heritage vulnerability in a changing and directional climate

[EN] RESCUhE Project (Improving structural RESilience of Cultural HEritage to directional extreme hydro-meteorological events in the context of the Climate Change) is a coordinated IGME-UAM research project funded by Spanish Government (MCIN/AEI/10.13039/501100011033). The framework of this research is the predicted increase in climate change vulnerability of heritage sites and the current disconnection between both environmental research on material decay and the practical aspects of designing preventive conservation measurements.RESCUhE Project (Improving structural RESilience of Cultural HEritage to directional extreme hydro-meteorological events in the context of the Climate Change) is a coordinated IGME-UAM research project funded by Spanish Government (MCIN/AEI/10.13039/501100011033).Peer reviewe

The role of clinical and neuroimaging features in the diagnosis of CADASIL.

BACKGROUND: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the most common familial cerebral small vessel disease, caused by NOTCH3 gene mutations. The aim of our study was to identify clinical and neuroradiological features which would be useful in identifying which patients presenting with lacunar stroke and TIA are likely to have CADASIL. METHODS: Patients with lacunar stroke or TIA were included in the present study. For each patient, demographic and clinical data were collected. MRI images were centrally analysed for the presence of lacunar infarcts, microbleeds, temporal lobe involvement, global atrophy and white matter hyperintensities. RESULTS: 128 patients (mean age 56.3 ± 12.4 years) were included. A NOTCH3 mutation was found in 12.5% of them. A family history of stroke, the presence of dementia and external capsule lesions on MRI were the only features significantly associated with the diagnosis of CADASIL. Although thalamic, temporal pole gliosis and severe white matter hyperintensities were less specific for CADASIL diagnosis, the combination of a number of these factors together with familial history for stroke result in a higher positive predictive value and specificity. CONCLUSIONS: A careful familial history collection and neuroradiological assessment can identify patients in whom NOTCH3 genetic testing has a higher yield.The Lombardia GENS project has received funding from the Regione Lombardia Government as a Research Independent Project (DGR n°VIII/006128-12/12/2007). Lombardia GENS is an investigator-driven, academic, non-profit consortium and is publicly funded. Hugh Markus is supported by an NIHR Senior Investigator award and his work is supported by the Cambridge University Hospitals NIHR Biomedical Research Centr