Articles | Volume 7, issue 2
https://doi.org/10.5194/se-7-579-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/se-7-579-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Research article
| 
13 Apr 2016
Research article |
| 13 Apr 2016
Insights on high-grade deformation in quartzo-feldspathic gneisses during the early Variscan exhumation of the Cabo Ortegal nappe, NW Iberia
Francisco José Fernández
CORRESPONDING AUTHOR
Departamento de Geología, Universidad de Oviedo,
Jesús Arias de Velasco s/n, 33005 Oviedo, Spain
Sergio Llana-Fúnez
Departamento de Geología, Universidad de Oviedo,
Jesús Arias de Velasco s/n, 33005 Oviedo, Spain
Pablo Valverde-Vaquero
Área de Laboratorios, Instituto Geológico y Minero
de España, La Calera 1, 28760 Tres Cantos, Spain
Alberto Marcos
Departamento de Geología, Universidad de Oviedo,
Jesús Arias de Velasco s/n, 33005 Oviedo, Spain
Pedro Castiñeiras
Departamento de Petrología y Geoquímica,
Universidad Complutense de Madrid, José Antonio Novais 12, 28040 Madrid,
Spain
Related authors
Pedro Castiñeiras, Juan Gómez Barreiro, Francisco J. Fernández, Carmen Aguilar, and José Manuel Benítez Pérez
Solid Earth Discuss., https://doi.org/10.5194/se-2020-53, https://doi.org/10.5194/se-2020-53, 2020
Revised manuscript not accepted
Jorge Acevedo, Gabriela Fernández-Viejo, Sergio Llana-Fúnez, Carlos López-Fernández, Javier Olona, and Diego Pérez-Millán
Solid Earth, 13, 659–679, https://doi.org/10.5194/se-13-659-2022, https://doi.org/10.5194/se-13-659-2022, 2022
Short summary
Short summary
The NW Iberian Peninsula provides one of the most complete Variscan sections in Europe, showing the transition between a sedimentary domain with folds and thrust and a metamorphic domain with igneous intrusions. By processing the seismic ambient noise recorded by several seismograph networks in this area, new 3-D S-wave velocity and radial anisotropy models were created. These models reveal the limit between the two domains, delineating the core of the large western European Variscan Belt.
Pedro Castiñeiras, Juan Gómez Barreiro, Francisco J. Fernández, Carmen Aguilar, and José Manuel Benítez Pérez
Solid Earth Discuss., https://doi.org/10.5194/se-2020-53, https://doi.org/10.5194/se-2020-53, 2020
Revised manuscript not accepted
Francisco J. Rubio Pascual, Luis M. Martín Parra, Pablo Valverde-Vaquero, Alejandro Díez Montes, Manuel P. Hacar Rodríguez, Justo Iglesias, Rubén Díez Fernández, Gloria Gallastegui, Nemesio Heredia, and L. Roberto Rodríguez Fernández
Solid Earth Discuss., https://doi.org/10.5194/se-2020-25, https://doi.org/10.5194/se-2020-25, 2020
Preprint withdrawn
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Jessica Barabasch, Joyce Schmatz, Jop Klaver, Alexander Schwedt, and Janos L. Urai
Solid Earth, 14, 271–291, https://doi.org/10.5194/se-14-271-2023, https://doi.org/10.5194/se-14-271-2023, 2023
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Nicolás Molnar and Susanne Buiter
Solid Earth, 14, 213–235, https://doi.org/10.5194/se-14-213-2023, https://doi.org/10.5194/se-14-213-2023, 2023
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Tania Habel, Martine Simoes, Robin Lacassin, Daniel Carrizo, and German Aguilar
Solid Earth, 14, 17–42, https://doi.org/10.5194/se-14-17-2023, https://doi.org/10.5194/se-14-17-2023, 2023
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The Central Andes are one of the most emblematic reliefs on Earth, but their western flank remains understudied. Here we explore two rare key sites in the hostile conditions of the Atacama desert to build cross-sections, quantify crustal shortening, and discuss the timing of this deformation at ∼20–22°S. We propose that the structures of the Western Andes accommodated significant crustal shortening here, but only during the earliest stages of mountain building.
Naïm Célini, Frédéric Mouthereau, Abdeltif Lahfid, Claude Gout, and Jean-Paul Callot
Solid Earth, 14, 1–16, https://doi.org/10.5194/se-14-1-2023, https://doi.org/10.5194/se-14-1-2023, 2023
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We investigate the peak temperature of sedimentary rocks of the SW Alps (France), using Raman spectroscopy on carbonaceous material. This method provides an estimate of the peak temperature achieved by organic-rich rocks. To determine the timing and the tectonic context of the origin of these temperatures we use 1D thermal modelling. We find that the high temperatures up to 300 °C were achieved during precollisional extensional events, not during tectonic burial in the Western Alps.
Pâmela Cristina Richetti, Frank Zwaan, Guido Schreurs, Renata S. Schmitt, and Timothy Chris Schmid
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The Araripe Basin in NE Brazil was originally formed during Cretaceous times, as South America and Africa broke up. The basin is an important analogue to offshore South Atlantic break-up basins; its sediments were uplifted and are now found at a 1000 m height, allowing for study, but the cause of the uplift remains debated. Here we ran a series of tectonic laboratory experiments that show how a specific plate tectonic configuration can explain the evolution of the Araripe Basin.
Luke N. J. Wedmore, Tess Turner, Juliet Biggs, Jack N. Williams, Henry M. Sichingabula, Christine Kabumbu, and Kawawa Banda
Solid Earth, 13, 1731–1753, https://doi.org/10.5194/se-13-1731-2022, https://doi.org/10.5194/se-13-1731-2022, 2022
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Mapping and compiling the attributes of faults capable of hosting earthquakes are important for the next generation of seismic hazard assessment. We document 18 active faults in the Luangwa Rift, Zambia, in an active fault database. These faults are between 9 and 207 km long offset Quaternary sediments, have scarps up to ~30 m high, and are capable of hosting earthquakes from Mw 5.8 to 8.1. We associate the Molaza Fault with surface ruptures from two unattributed M 6+ 20th century earthquakes.
Michał P. Michalak, Lesław Teper, Florian Wellmann, Jerzy Żaba, Krzysztof Gaidzik, Marcin Kostur, Yuriy P. Maystrenko, and Paulina Leonowicz
Solid Earth, 13, 1697–1720, https://doi.org/10.5194/se-13-1697-2022, https://doi.org/10.5194/se-13-1697-2022, 2022
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When characterizing geological/geophysical surfaces, various geometric attributes are calculated, such as dip angle (1D) or dip direction (2D). However, the boundaries between specific values may be subjective and without optimization significance, resulting from using default color palletes. This study proposes minimizing cosine distance among within-cluster observations to detect 3D anomalies. Our results suggest that the method holds promise for identification of megacylinders or megacones.
Erik M. Young, Christie D. Rowe, and James D. Kirkpatrick
Solid Earth, 13, 1607–1629, https://doi.org/10.5194/se-13-1607-2022, https://doi.org/10.5194/se-13-1607-2022, 2022
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Studying how earthquakes spread deep within the faults they originate from is crucial to improving our understanding of the earthquake process. We mapped preserved ancient earthquake surfaces that are now exposed in South Africa and studied their relationship with the shape and type of rocks surrounding them. We determined that these surfaces are not random and are instead associated with specific kinds of rocks and that their shape is linked to the evolution of the faults in which they occur.
Sivaji Lahiri, Kitty L. Milliken, Peter Vrolijk, Guillaume Desbois, and Janos L. Urai
Solid Earth, 13, 1513–1539, https://doi.org/10.5194/se-13-1513-2022, https://doi.org/10.5194/se-13-1513-2022, 2022
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Understanding the mechanism of mechanical compaction is important. Previous studies on mechanical compaction were mostly done by performing experiments. Studies on natural rocks are rare due to compositional heterogeneity of the sedimentary succession with depth. Due to remarkable similarity in composition and grain size, the Sumatra subduction complex provides a unique opportunity to study the micromechanism of mechanical compaction on natural samples.
Dongwon Lee, Nikolaos Karadimitriou, Matthias Ruf, and Holger Steeb
Solid Earth, 13, 1475–1494, https://doi.org/10.5194/se-13-1475-2022, https://doi.org/10.5194/se-13-1475-2022, 2022
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This research article focuses on filtering and segmentation methods employed in high-resolution µXRCT studies for crystalline rocks, bearing fractures, or fracture networks, of very small aperture. Specifically, we focus on the identification of artificially induced (via quenching) fractures in Carrara marble samples. Results from the same dataset from all five different methods adopted were produced and compared with each other in terms of their output quality and time efficiency.
Alberto Ceccato, Giulia Tartaglia, Marco Antonellini, and Giulio Viola
Solid Earth, 13, 1431–1453, https://doi.org/10.5194/se-13-1431-2022, https://doi.org/10.5194/se-13-1431-2022, 2022
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The Earth's surface is commonly characterized by the occurrence of fractures, which can be mapped, and their can be geometry quantified on digital representations of the surface at different scales of observation. Here we present a series of analytical and statistical tools, which can aid the quantification of fracture spatial distribution at different scales. In doing so, we can improve our understanding of how fracture geometry and geology affect fluid flow within the fractured Earth crust.
Giulio Viola, Giovanni Musumeci, Francesco Mazzarini, Lorenzo Tavazzani, Manuel Curzi, Espen Torgersen, Roelant van der Lelij, and Luca Aldega
Solid Earth, 13, 1327–1351, https://doi.org/10.5194/se-13-1327-2022, https://doi.org/10.5194/se-13-1327-2022, 2022
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A structural-geochronological approach helps to unravel the Zuccale Fault's architecture. By mapping its internal structure and dating some of its fault rocks, we constrained a deformation history lasting 20 Myr starting at ca. 22 Ma. Such long activity is recorded by now tightly juxtaposed brittle structural facies, i.e. different types of fault rocks. Our results also have implications on the regional evolution of the northern Apennines, of which the Zuccale Fault is an important structure.
Wan-Lin Hu
Solid Earth, 13, 1281–1290, https://doi.org/10.5194/se-13-1281-2022, https://doi.org/10.5194/se-13-1281-2022, 2022
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Having a seismic image is generally expected to enable us to better determine fault geometry and thus estimate geological slip rates accurately. However, the process of interpreting seismic images may introduce unintended uncertainties, which have not yet been widely discussed. Here, a case of a shear fault-bend fold in the frontal Himalaya is used to demonstrate how differences in interpretations can affect the following estimates of slip rates and dependent conclusions.
Manuel D. Menzel, Janos L. Urai, Estibalitz Ukar, Thierry Decrausaz, and Marguerite Godard
Solid Earth, 13, 1191–1218, https://doi.org/10.5194/se-13-1191-2022, https://doi.org/10.5194/se-13-1191-2022, 2022
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Mantle rocks can bind large quantities of carbon by reaction with CO2, but this capacity requires fluid pathways not to be clogged by carbonate. We studied mantle rocks from Oman to understand the mechanisms allowing their transformation into carbonate and quartz. Using advanced imaging techniques, we show that abundant veins were essential fluid pathways driving the reaction. Our results show that tectonic stress was important for fracture opening and a key ingredient for carbon fixation.
Jean-Baptiste P. Koehl, Steffen G. Bergh, and Arthur G. Sylvester
Solid Earth, 13, 1169–1190, https://doi.org/10.5194/se-13-1169-2022, https://doi.org/10.5194/se-13-1169-2022, 2022
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The San Andreas fault is a major active fault associated with ongoing earthquake sequences in southern California. The present study investigates the development of the Indio Hills area in the Coachella Valley along the main San Andreas fault and the Indio Hills fault. The Indio Hills area is located near an area with high ongoing earthquake activity (Brawley seismic zone), and, therefore, its recent tectonic evolution has implications for earthquake prediction.
Jin Lai, Dong Li, Yong Ai, Hongkun Liu, Deyang Cai, Kangjun Chen, Yuqiang Xie, and Guiwen Wang
Solid Earth, 13, 975–1002, https://doi.org/10.5194/se-13-975-2022, https://doi.org/10.5194/se-13-975-2022, 2022
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(1) Structural diagenesis analysis is performed on the ultra-deep tight sandstone. (2) Fracture and intergranular pores are related to the low in situ stress magnitudes. (3) Dissolution is associated with the presence of fracture.
Hamed Fazlikhani, Wolfgang Bauer, and Harald Stollhofen
Solid Earth, 13, 393–416, https://doi.org/10.5194/se-13-393-2022, https://doi.org/10.5194/se-13-393-2022, 2022
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Interpretation of newly acquired FRANKEN 2D seismic survey data in southeeastern Germany shows that upper Paleozoic low-grade metasedimentary rocks and possible nappe units are transported by Variscan shear zones to ca. 65 km west of the Franconian Fault System (FFS). We show that the locations of post-Variscan upper Carboniferous–Permian normal faults and associated graben and half-graben basins are controlled by the geometry of underlying Variscan shear zones.
Xiaodong Ma, Marian Hertrich, Florian Amann, Kai Bröker, Nima Gholizadeh Doonechaly, Valentin Gischig, Rebecca Hochreutener, Philipp Kästli, Hannes Krietsch, Michèle Marti, Barbara Nägeli, Morteza Nejati, Anne Obermann, Katrin Plenkers, Antonio P. Rinaldi, Alexis Shakas, Linus Villiger, Quinn Wenning, Alba Zappone, Falko Bethmann, Raymi Castilla, Francisco Seberto, Peter Meier, Thomas Driesner, Simon Loew, Hansruedi Maurer, Martin O. Saar, Stefan Wiemer, and Domenico Giardini
Solid Earth, 13, 301–322, https://doi.org/10.5194/se-13-301-2022, https://doi.org/10.5194/se-13-301-2022, 2022
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Questions on issues such as anthropogenic earthquakes and deep geothermal energy developments require a better understanding of the fractured rock. Experiments conducted at reduced scales but with higher-resolution observations can shed some light. To this end, the BedrettoLab was recently established in an existing tunnel in Ticino, Switzerland, with preliminary efforts to characterize realistic rock mass behavior at the hectometer scale.
Berit Schwichtenberg, Florian Fusseis, Ian B. Butler, and Edward Andò
Solid Earth, 13, 41–64, https://doi.org/10.5194/se-13-41-2022, https://doi.org/10.5194/se-13-41-2022, 2022
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Hydraulic rock properties such as porosity and permeability are relevant factors that have an impact on groundwater resources, geological repositories and fossil fuel reservoirs. We investigate the influence of chemical compaction upon the porosity evolution in salt–biotite mixtures and related transport length scales by conducting laboratory experiments in combination with 4-D analysis. Our observations invite a renewed discussion of the effect of sheet silicates on chemical compaction.
David Healy and Stephen Paul Hicks
Solid Earth, 13, 15–39, https://doi.org/10.5194/se-13-15-2022, https://doi.org/10.5194/se-13-15-2022, 2022
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The energy transition requires operations in faulted rocks. To manage the technical challenges and public concern over possible induced earthquakes, we need to quantify the risks. We calculate the probability of fault slip based on uncertain inputs, stresses, fluid pressures, and the mechanical properties of rocks in fault zones. Our examples highlight the specific gaps in our knowledge. Citizen science projects could produce useful data and include the public in the discussions about hazards.
Manuel I. de Paz-Álvarez, Thomas G. Blenkinsop, David M. Buchs, George E. Gibbons, and Lesley Cherns
Solid Earth, 13, 1–14, https://doi.org/10.5194/se-13-1-2022, https://doi.org/10.5194/se-13-1-2022, 2022
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We describe a virtual geological mapping course implemented in response to travelling and social restrictions derived from the ongoing COVID-19 pandemic. The course was designed to replicate a physical mapping exercise as closely as possible with the aid of real field data and photographs collected by the authors during previous years in the Cantabrian Zone (NW Spain). The course is delivered through Google Earth via a KMZ file with outcrop descriptions and links to GitHub-hosted photographs.
Yueyang Xia, Jacob Geersen, Dirk Klaeschen, Bo Ma, Dietrich Lange, Michael Riedel, Michael Schnabel, and Heidrun Kopp
Solid Earth, 12, 2467–2477, https://doi.org/10.5194/se-12-2467-2021, https://doi.org/10.5194/se-12-2467-2021, 2021
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The 2 June 1994 Java tsunami earthquake ruptured in a seismically quiet subduction zone and generated a larger-than-expected tsunami. Here, we re-process a seismic line across the rupture area. We show that a subducting seamount is located up-dip of the mainshock in a region that did not rupture during the earthquake. Seamount subduction modulates the topography of the marine forearc and acts as a seismic barrier in the 1994 earthquake rupture.
Steffen Abe and Hagen Deckert
Solid Earth, 12, 2407–2424, https://doi.org/10.5194/se-12-2407-2021, https://doi.org/10.5194/se-12-2407-2021, 2021
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We use numerical simulations and laboratory experiments on rock samples to investigate how stress conditions influence the geometry and roughness of fracture surfaces. The roughness of the surfaces was analyzed in terms of absolute roughness and scaling properties. The results show that the surfaces are self-affine but with different scaling properties between the numerical models and the real rock samples. Results suggest that stress conditions have little influence on the surface roughness.
Chao Deng, Rixiang Zhu, Jianhui Han, Yu Shu, Yuxiang Wu, Kefeng Hou, and Wei Long
Solid Earth, 12, 2327–2350, https://doi.org/10.5194/se-12-2327-2021, https://doi.org/10.5194/se-12-2327-2021, 2021
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This study uses seismic reflection data to interpret the geometric relationship and evolution of intra-basement and rift-related structures in the Enping sag in the northern South China Sea. Our observations suggest the primary control of pre-existing thrust faults is the formation of low-angle normal faults, with possible help from low-friction materials, and the significant role of pre-existing basement thrust faults in fault geometry, paleotopography, and syn-rift stratigraphy of rift basins.
Sonia Yeung, Marnie Forster, Emmanuel Skourtsos, and Gordon Lister
Solid Earth, 12, 2255–2275, https://doi.org/10.5194/se-12-2255-2021, https://doi.org/10.5194/se-12-2255-2021, 2021
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We do not know when the ancient Tethys Ocean lithosphere began to founder, but one clue can be found in subduction accreted tectonic slices, including Gondwanan basement terranes on the island of Ios, Cyclades, Greece. We propose a 250–300 km southwards jump of the subduction megathrust with a period of flat-slab subduction followed by slab break-off. The initiation and its subsequent rollback of a new subduction zone would explain the onset of Oligo–Miocene extension and accompanying magmatism.
Rahul Prabhakaran, Giovanni Bertotti, Janos Urai, and David Smeulders
Solid Earth, 12, 2159–2209, https://doi.org/10.5194/se-12-2159-2021, https://doi.org/10.5194/se-12-2159-2021, 2021
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Rock fractures are organized as networks with spatially varying arrangements. Due to networks' influence on bulk rock behaviour, it is important to quantify network spatial variation. We utilize an approach where fracture networks are treated as spatial graphs. By combining graph similarity measures with clustering techniques, spatial clusters within large-scale fracture networks are identified and organized hierarchically. The method is validated on a dataset with nearly 300 000 fractures.
Olivier Lacombe, Nicolas E. Beaudoin, Guilhem Hoareau, Aurélie Labeur, Christophe Pecheyran, and Jean-Paul Callot
Solid Earth, 12, 2145–2157, https://doi.org/10.5194/se-12-2145-2021, https://doi.org/10.5194/se-12-2145-2021, 2021
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This paper aims to illustrate how the timing and duration of contractional deformation associated with folding in orogenic forelands can be constrained by the dating of brittle mesostructures observed in folded strata. The study combines new and already published absolute ages of fractures to provide, for the first time, an educated discussion about the factors controlling the duration of the sequence of deformation encompassing layer-parallel shortening, fold growth, and late fold tightening.
Vincent Famin, Hugues Raimbourg, Muriel Andreani, and Anne-Marie Boullier
Solid Earth, 12, 2067–2085, https://doi.org/10.5194/se-12-2067-2021, https://doi.org/10.5194/se-12-2067-2021, 2021
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Sediments accumulated in accretionary prisms are deformed by the compression imposed by plate subduction. Here we show that deformation of the sediments transforms some minerals in them. We suggest that these mineral transformations are due to the proliferation of microorganisms boosted by deformation. Deformation-enhanced microbial proliferation may change our view of sedimentary and tectonic processes in subduction zones.
Marta Adamuszek, Dan M. Tămaş, Jessica Barabasch, and Janos L. Urai
Solid Earth, 12, 2041–2065, https://doi.org/10.5194/se-12-2041-2021, https://doi.org/10.5194/se-12-2041-2021, 2021
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We analyse folded multilayer sequences in the Ocnele Mari salt mine (Romania) to gain insight into the long-term rheological behaviour of rock salt. Our results indicate the large role of even a small number of impurities in the rock salt for its effective mechanical behaviour. We demonstrate how the development of folds that occur at various scales can be used to constrain the viscosity ratio in the deformed multilayer sequence.
Dario Zampieri, Paola Vannoli, and Pierfrancesco Burrato
Solid Earth, 12, 1967–1986, https://doi.org/10.5194/se-12-1967-2021, https://doi.org/10.5194/se-12-1967-2021, 2021
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The long-lived Schio-Vicenza Fault System is a major shear zone cross-cutting the foreland and the thrust belt of the eastern southern Alps. We review 150 years of scientific works and explain its activity and kinematics, characterized by sinistral and dextral transcurrent motion along its southern and northern sections, respectively, by a geodynamic model that has the Adria indenter as the main actor and coherently reconciles the available geological and geophysical evidence collected so far.
Vincent F. Verwater, Eline Le Breton, Mark R. Handy, Vincenzo Picotti, Azam Jozi Najafabadi, and Christian Haberland
Solid Earth, 12, 1309–1334, https://doi.org/10.5194/se-12-1309-2021, https://doi.org/10.5194/se-12-1309-2021, 2021
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Balancing along geological cross sections reveals that the Giudicarie Belt comprises two kinematic domains. The SW domain accommodated at least ~ 18 km Late Oligocene to Early Miocene shortening. Since the Middle Miocene, the SW domain experienced at least ~ 12–22 km shortening, whereas the NE domain underwent at least ~ 25–35 km. Together, these domains contributed to ~ 40–47 km of sinistral offset of the Periadriatic Fault along the Northern Giudicarie Fault since the Late Oligocene.
Emma A. H. Michie, Mark J. Mulrooney, and Alvar Braathen
Solid Earth, 12, 1259–1286, https://doi.org/10.5194/se-12-1259-2021, https://doi.org/10.5194/se-12-1259-2021, 2021
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Generating an accurate model of the subsurface is crucial when assessing a site for CO2 storage, particularly for a fault-bound storage site that may act as a seal or could reactivate upon CO2 injection. However, we have shown how picking strategy, i.e. line spacing, chosen to create the model significantly influences any subsequent fault analyses but is surprisingly rarely discussed. This analysis has been performed on the Vette Fault bounding the Smeaheia potential CO2 storage site.
David J. Anastasio, Frank J. Pazzaglia, Josep M. Parés, Kenneth P. Kodama, Claudio Berti, James A. Fisher, Alessandro Montanari, and Lorraine K. Carnes
Solid Earth, 12, 1125–1142, https://doi.org/10.5194/se-12-1125-2021, https://doi.org/10.5194/se-12-1125-2021, 2021
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The anisotropy of magnetic susceptibility (AMS) technique provides an effective way to interpret deforming mountain belts. In both the Betics, Spain, and Apennines, Italy, weak but well-organized AMS fabrics were recovered from young unconsolidated and unburied rocks that could not be analyzed with more traditional methods. Collectively, these studies demonstrate the novel ways that AMS can be combined with other data to resolve earthquake hazards in space and time.
Stefano Urbani, Guido Giordano, Federico Lucci, Federico Rossetti, and Gerardo Carrasco-Núñez
Solid Earth, 12, 1111–1124, https://doi.org/10.5194/se-12-1111-2021, https://doi.org/10.5194/se-12-1111-2021, 2021
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Structural studies in active calderas have a key role in the exploration of geothermal systems. We reply in detail to the points raised by the comment of Norini and Groppelli (2020), strengthening the relevance of our structural fieldwork for geothermal exploration and exploitation in active caldera geothermal systems including the Los Humeros caldera.
Jakob Bolz and Jonas Kley
Solid Earth, 12, 1005–1024, https://doi.org/10.5194/se-12-1005-2021, https://doi.org/10.5194/se-12-1005-2021, 2021
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To assess the role smaller graben structures near the southern edge of the Central European Basin System play in the basin’s overall deformational history, we take advantage of a feature found on some of these structures, where slivers from older rock units appear along the graben's main fault, surrounded on both sides by younger strata. The implications for the geometry of the fault provide a substantially improved estimate for the magnitude of normal and thrust motion along the fault system.
Domingo G. A. M. Aerden, Alejandro Ruiz-Fuentes, Mohammad Sayab, and Aidan Forde
Solid Earth, 12, 971–992, https://doi.org/10.5194/se-12-971-2021, https://doi.org/10.5194/se-12-971-2021, 2021
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We studied the geometry of foliations and microfolds preserved within metamorphic garnet crystals using X-ray tomography. The studied rocks are blueschists from Ile de Groix formed during Late Devonian subduction of Gondwana under Armorica. Several sets of differently oriented microfabrics were found recording variations in the direction of subduction. Comparison with similar data for Iberia supports that Iberia rotated only 10–20° during the Cretaceous opening of the North Atlantic.
Alessandro Tibaldi, Noemi Corti, Emanuela De Beni, Fabio Luca Bonali, Susanna Falsaperla, Horst Langer, Marco Neri, Massimo Cantarero, Danilo Reitano, and Luca Fallati
Solid Earth, 12, 801–816, https://doi.org/10.5194/se-12-801-2021, https://doi.org/10.5194/se-12-801-2021, 2021
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The Northeast Rift of Mt Etna is affected by ground deformation linked to gravity sliding of the volcano flank and dike injection. Drone surveys show that the rift is affected by NE-striking extensional fractures and normal faults. Given an age of 1614 CE for the offset lavas, we obtained an extension rate of 1.9 cm yr−1 for the last 406 years. The stress field is characterised by a NW–SE σHmin. Drone surveys allow us to quickly collect data with a resolution of 2–3 cm.
Matteo Demurtas, Steven A.F. Smith, Elena Spagnuolo, and Giulio Di Toro
Solid Earth, 12, 595–612, https://doi.org/10.5194/se-12-595-2021, https://doi.org/10.5194/se-12-595-2021, 2021
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We performed shear experiments on calcite–dolomite gouge mixtures to better understand the behaviour of carbonates during sub-seismic to seismic deformation in the shallow crust. The development of a foliation in the gouge was only restricted to coseismic sliding, whereas fluidisation occurred over a wide range of slip velocities (sub-seismic to coseismic) in the presence of water. These observations will contribute to a better interpretation of the rock record.
James Gilgannon, Marius Waldvogel, Thomas Poulet, Florian Fusseis, Alfons Berger, Auke Barnhoorn, and Marco Herwegh
Solid Earth, 12, 405–420, https://doi.org/10.5194/se-12-405-2021, https://doi.org/10.5194/se-12-405-2021, 2021
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Using experiments that simulate deep tectonic interfaces, known as viscous shear zones, we found that these zones spontaneously develop periodic sheets of small pores. The presence of porous layers in deep rocks undergoing tectonic deformation is significant because it requires a change to the current model of how the Earth deforms. Emergent porous layers in viscous rocks will focus mineralising fluids and could lead to the seismic failure of rocks that are never supposed to have this occur.
Cited articles
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Short summary
High-grade gneisses record two partial melting events: early Ordovician and early Variscan. Primary sedimentary layering is well preserved locally at the top of the sequence. First stage of the exhumation process occurred in ∼ 10 Ma.
Strain was progressively localized along the boundaries of the migmatitic qz-fsp gneisses. Deformation reduced substantially the thickness of the gneissic rock sequence. "Internal" extrusion of the migmatites is documented.
High-grade gneisses record two partial melting events: early Ordovician and early Variscan....
