On the material dependence of experimental shear fracture orientation

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Fracturing of ductile anisotropic multilayers : influence of material strength

Acknowledgements. This work was financed through the research project CGL2004-03657, funded by the Spanish Ministry of Education and Science. We thank J. Carreras, E. Druguet and L. M. Castaño for discussions on some aspects related to this work. We gratefully acknowledge G. Zulauf and T. Duretz, whose constructive reviews greatly improved the manuscript, and the editorial guidance of N. MancktelowPeer reviewedPublisher PD

La evolución de una red de venas de yeso en contextos tectónicos compresivos: El caso del anticlinorio del Montsant (NE España)

The Montsant anticlinorium is part of the Pàndols-Cavalls-Montsant tectonic line situated in the southwestern area of the Catalan Coastal Ranges, adjacent to the contact with the Tertiary Ebro Basin. We have interpreted this Alpine structure as a triangular type I zone with two opposite faults. The centre of the anticlinorium is formed by middle Muschelkalk facies with intensively deformed gypsum layers and an intensively deformed zone with an associated framework of satin spar gypsum veins. A field structural analysis reveals that there are two sets of veins: one associated with a pre-folding stage (before the Alpine orogeny), and another one related to the development of the Montsant anticlinorium, and therefore syn-folding (and Alpine in age)El anticlinorio del Montsant forma parte de la línea tectónica de PándolsCavalls-Montsant, situada al Suroeste de la Cordillera Costera Catalana, y adyacente al contacto con la Cuenca del Ebro. Esta estructura Alpina se interpreta como una zona triangular de Tipo I con dos flancos opuestos. El centro del anticlinorio está formado por facies del Muschelkalk medio con capas de yeso altamente deformadas formando una red de venas de yeso de tipo satin spar. Mediante un análisis estructural de campo hemos identificado dos conjuntos de venas: uno asociado a la etapa previa al plegamiento (antes de la orogenia Alpina) y el otro asociado a la formación del anticlionorio del Montsant durante la orogenia Alpin

Alpine Ductile Deformation of the Upper Iberian Collided Margin (Eaux-Chaudes Massif, West-Central Pyrenean Hinterland, France)

Altres ajuts: acords transformatius de la UABThe Eaux-Chaudes massif provides keys to unravel the deep-seated deformation of the Iberian rifted margin during the Alpine orogeny in the Pyrenees. The massif conforms to an inlier of upper Cretaceous carbonate rocks within the Paleozoic basement of the western Axial Zone, originally deposited in the upper margin shelf before the Cenozoic collision. New geological mapping and cross-section construction lead to the description of the lateral structural variation from a km-scale fold nappe in the west to a ductile, imbricate fold-thrust fan in the east. The transition from a Variscan pluton to Devonian metasediments underlying the autochthonous Cretaceous induced this structural change. Recumbent folding, which involved upper Paleozoic rocks, was facilitated by a lower detachment in Silurian slates and an upper detachment in an overlying Keuper shale and evaporite thrust sheet. Remnants of this allochthonous sheet form shale and ophite bodies pinched within the upper Cretaceous carbonates, conforming unusual tertiary welds. Ductile shear in the overturned limb of the Eaux-Chaudes fold nappe imparted strong mylonitic foliation in carbonate rocks, often accompanied by N-S stretching lineation and top-to-the-south kinematic indicators. The burial of the massif by basement-involved thrust sheets and the Keuper sheet, along with their Mesozoic-Cenozoic cover, account for ductile deformation conditions and a structural style not reported hitherto for the Alpine Pyrenees. A hypothesis for the tectonic restoration of this part of the Pyrenean hinterland is finally proposed

Strain and vorticity analysis using small-scale faults and associated drag folds

This work was financed through the PhD grant BES-2003-0755 to EGR and research project CGL2004-03657, both funded by the Spanish Ministry of Education and Science. We thank Jens Becker and Anne Peschler for their help with the BASIL modelling. We gratefully acknowledge D. Jiang and T. Bell, whose constructive reviews greatly improved the manuscript.Peer reviewedPostprin

Fluid pressure drops during stimulation of segmented faults in deep geothermal reservoirs

Acknowledgements The Institut Cartogràfic i Geològic de Catalunya is acknowledged for their support in our investigation of Geothermal resources. G. Piris was supported by an AGAUR grant of the Industrial Doctorate programme 2016-DI-031. EGR acknowledges the support of the Beatriu de Pinós programme of the Government of Catalonia’s Secretariat for Universities and Research of the Department of Economy and Knowledge (2016 BP 00208). The authors would like to thank three anonymous reviewers and the editors Dr. Carola Meller and Prof. Olaf Kolditz for their helpful comments that improved this manuscript.Peer reviewedPublisher PD

Modelling the influence of air on the deformation and recrystallisation mechanisms in polar firn and ice

Within their upper approximately thousand meters, ice sheets on Earth contain a significant amount of air and air hydrates below. In the permeable firn, this air is still exchanging with the atmosphere and is under atmospheric pressure, whereas the air bubbles are entrapped at the firn-ice transition 60 – 120 m depth. As recent research showed, the presence of air bubbles can significantly influence microdynamical processes such as grain growth and grain boundary migration (Azuma et al., 2012, Roessiger et al., 2014). Understanding the dominant deformation mechanisms has essential implications on paleo-atmosphere research and allows more realistic modelling of ice sheet dynamics. Therefore, numerical models were set up and performed focussing on the implications of the presence of bubbles on recrystallisation and the mechanical properties of ice with air inclusions. The 2D numerical microstructural modelling platform Elle was coupled to the full-field crystal plasticity code of Lebensohn (2001), which is using a Fast Fourier Transform (FFT) following the approach by Griera et al. (2013). Taking into account the mechanical anisotropy of ice, FFT calculates the viscoplastic response of polycrystalline and polyphase materials that deform by dislocation glide, predicts lattice re-orientation and using the local gradient of the strain-rate field, dislocation densities are calculated. FFT was used for the simulation of dynamic recrystallization of pure ice by Montagnat et al. (2013). Polyphase grain boundary migration driven by surface energy and internal strain energy reduction was incorporated in the code and now also enables us to model deformation of ice with air bubbles. The approach is based on the methodology of Becker et al. (2008) and Roessiger et al. (2014). During Deformation, spherical to elliptical bubble shapes are only maintained, when surface energy based recrystallisation is activated, whereas they quickly collapse at low strains in the absence of recrystallisation. The presence of bubbles leads to increased localization of stress, strain and dislocation densities, a reduction of the bulk strength of the bubbly ice is observed. Furthermore, strain-induced grain boundary migration already occuring in the uppermost levels of ice sheets (Kipfstuhl et al. 2009, Weikusat et al. 2009) is confirmed by our modelling. References Azuma, N., Miyakoshi, T., Yokoyama, S., Takata, M., 2012. Journal of Structural Geology 42, 184- 193. Becker, J.K., Bons, P.D., Jessell, M.W., 2008. Computers & Geosciences 34, 201-212. Bons, P.D., Koehn, D., Jessell, M.W. (Eds.), 2008. Microdynamic Simulation. Springer, Berlin. Kipfstuhl, S., Faria, S.H., Azuma, N., Freitag, J., Hamann, I., Kaufmann, P., Miller, H., Weiler, K., Wilhelms, F., 2009. Journal of Geophysical Research 114, B05204. Lebensohn, R.A., 2001. Acta Mater 49 (14), 2723e2737. Montagnat, M., Castelnau, O., Bons, P.D., Faria, S.H., Gagliardini, O., Gillet-Chaulet, F., Grennerat, F., Griera, A., Lebensohn, R.A., Moulinec, H., Roessiger, J., Suquet, P., 2014. Journal of Structural Geology 61, 78-108 Rößiger, J., Bons, P.D., Faria, S.H., 2014. Journal of Structural Geology 61, 123-132 Weikusat, I., Kipfstuhl, S., Faria, S.H., Azuma, N., Miyamoto, A., 2009. Journal of Glaciology 55, 461-472

3DHIP-calculator-A new tool to stochastically assess deep geothermal potential using the heat-in-place method from voxel-based 3D geological models

The assessment of the deep geothermal potential is an essential task during the early phases of any geothermal project. The well-known "Heat-In-Place" volumetric method is the most widely used technique to estimate the available stored heat and the recoverable heat fraction of deep geothermal reservoirs at the regional scale. Different commercial and open-source software packages have been used to date to estimate these parameters. However, these tools are either not freely available, can only consider the entire reservoir volume or a specific part as a single-voxel model, or are restricted to certain geographical areas. The 3DHIP-Calculator tool presented in this contribution is an open-source software designed for the assessment of the deep geothermal potential at the regional scale using the volumetric method based on a stochastic approach. The tool estimates the Heat-In-Place and recoverable thermal energy using 3D geological and 3D thermal voxel models as input data. The 3DHIP-Calculator includes an easy-to-use graphical user interface (GUI) for visualizing and exporting the results to files for further postprocessing, including GIS-based map generation. The use and functionalities of the 3DHIP-Calculator are demonstrated through a case study of the Reus-Valls sedimentary basin (NE, Spain)

Origen de las dolomías en la zona de Riópar (SE España): implicaciones sobre la geología de la Zona Prebética

In the present study a petrographic description and C-O stable isotope data of dolostone occurrences at the Riópar area (Mesozoic Prebetic Zone) are presented. Results constrain the origin and dolomitization processes for each dolomitic unit providing new insights on the geology of the Prebetic. Dolostones are grouped in: i) large seismicscale stratabound dolostones hosted in limestones of Lower Jurassic, Middle Jurassic and Upper Cretaceous ages; and ii) stratabound and patchy dolostones hosted in a carbonatic sequence of Upper Jurassic to Lower Cretaceous age. Two dolomitizing origins have been distinguished: i) a low-temperature dolomitization originated from seawater (seismicscale stratabound dolomitized limestones); ii) a hydrothermal dolomitization originated by high temperature brines (stratabound and patchy dolomitized limestones). Results of this study can be used as a guide for other poorly known dolomitic areas in the Prebetic Zone.En este estudio se presenta la descripción petrográfica y los datos isotópicos de C y O de distintos cuerpos de dolomías en la zona de Riópar (Zona Mesozoica del Prebético). Los resultados obtenidos permiten acotar el origen de cada miembro dolomítico, aportando nuevos datos geológicos en el Prebético. Dichos cuerpos se agrupan en: i) dolomías estratiformes de gran extensión hospedadas en calizas del Jurásico Inferior y Medio, así como del Cretácico Superior; ii) dolomías de tipo estratiforme y en forma de parches hospedadas en una secuencia carbonatada del Jurásico Superior al Cretácico inferior. El origen de estas dolomitizaciones se atribuye a: i) interacción con agua marina presumiblemente a baja temperatura (dolomías estratiformes de gran extensión); ii) presencia de salmueras hidrotermales de alta temperatura (dolomías estratiformes y parcheadas). Estos resultados pueden servir de guía para otras áreas dolomitizadas poco estudiadas en la zona del Prebético.Depto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasTRUEMinisterio de Economía y Competitividad (MINECO)pu