Articles | Volume 7, issue 5
https://doi.org/10.5194/se-7-1331-2016
© 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-7-1331-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Research article
| 
16 Sep 2016
Research article |
| 16 Sep 2016
Mid-crustal shear zone development under retrograde conditions: pressure–temperature–fluid constraints from the Kuckaus Mylonite Zone, Namibia
Johann F. A. Diener
CORRESPONDING AUTHOR
Department of Geological Sciences, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa
Åke Fagereng
Department of Geological Sciences, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa
present address: School of Earth & Ocean Sciences, Cardiff University, Cardiff CF10 3AT, UK
Sukey A. J. Thomas
Department of Geological Sciences, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa
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Hugh Daigle, João C. Duarte, Ake Fagereng, Raphaël Paris, Patricia Persaud, Ángela María Gómez-García, and the Lisbon MagellanPlus Workshop Participants
Sci. Dril., 32, 101–111, https://doi.org/10.5194/sd-32-101-2023, https://doi.org/10.5194/sd-32-101-2023, 2023
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Natural hazards associated with the ocean can have a direct impact on coastal populations and even affect populations located far away from the coast. These hazards may interact, and they include tsunamis that result in major damage and catastrophic loss of life and submarine landslides, which themselves can produce tsunamis and damage subsea infrastructure. We present ideas for investigating these hazards with scientific ocean drilling.
Jack N. Williams, Luke N. J. Wedmore, Åke Fagereng, Maximilian J. Werner, Hassan Mdala, Donna J. Shillington, Christopher A. Scholz, Folarin Kolawole, Lachlan J. M. Wright, Juliet Biggs, Zuze Dulanya, Felix Mphepo, and Patrick Chindandali
Nat. Hazards Earth Syst. Sci., 22, 3607–3639, https://doi.org/10.5194/nhess-22-3607-2022, https://doi.org/10.5194/nhess-22-3607-2022, 2022
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We use geologic and GPS data to constrain the magnitude and frequency of earthquakes that occur along active faults in Malawi. These faults slip in earthquakes as the tectonic plates on either side of the East African Rift in Malawi diverge. Low divergence rates (0.5–1.5 mm yr) and long faults (5–200 km) imply that earthquakes along these faults are rare (once every 1000–10 000 years) but could have high magnitudes (M 7–8). These data can be used to assess seismic risk in Malawi.
Jack N. Williams, Hassan Mdala, Åke Fagereng, Luke N. J. Wedmore, Juliet Biggs, Zuze Dulanya, Patrick Chindandali, and Felix Mphepo
Solid Earth, 12, 187–217, https://doi.org/10.5194/se-12-187-2021, https://doi.org/10.5194/se-12-187-2021, 2021
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Earthquake hazard is often specified using instrumental records. However, this record may not accurately forecast the location and magnitude of future earthquakes as it is short (100s of years) relative to their frequency along geologic faults (1000s of years). Here, we describe an approach to assess this hazard using fault maps and GPS data. By applying this to southern Malawi, we find that its faults may host rare (1 in 10 000 years) M 7 earthquakes that pose a risk to its growing population.
Michael Hodge, Juliet Biggs, Åke Fagereng, Austin Elliott, Hassan Mdala, and Felix Mphepo
Solid Earth, 10, 27–57, https://doi.org/10.5194/se-10-27-2019, https://doi.org/10.5194/se-10-27-2019, 2019
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This work attempts to create a semi-automated algorithm (called SPARTA) to calculate height, width and slope of surface breaks produced by earthquakes on faults. We developed the Python algorithm using synthetic catalogues, which can include noise features such as vegetation, hills and ditches, which mimic natural environments. We then apply the algorithm to four fault scarps in southern Malawi, at the southern end of the East African Rift system, to understand their earthquake potential.
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Jinbao Su, Wenbin Zhu, and Guangwei Li
Solid Earth, 15, 1133–1141, https://doi.org/10.5194/se-15-1133-2024, https://doi.org/10.5194/se-15-1133-2024, 2024
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The late Mesozoic igneous rocks in the South China Block exhibit flare-ups and lulls, which form in compressional or extensional backgrounds. The ascending of magma forms a mush-like head and decreases crustal thickness. The presence of faults and pre-existing magmas will accelerate emplacement of underplating magma. The magmatism at different times may be formed under similar subduction conditions, and the boundary compression forces will delay magma ascent.
Peter Achtziger-Zupančič, Alberto Ceccato, Alba Simona Zappone, Giacomo Pozzi, Alexis Shakas, Florian Amann, Whitney Maria Behr, Daniel Escallon Botero, Domenico Giardini, Marian Hertrich, Mohammadreza Jalali, Xiaodong Ma, Men-Andrin Meier, Julian Osten, Stefan Wiemer, and Massimo Cocco
Solid Earth, 15, 1087–1112, https://doi.org/10.5194/se-15-1087-2024, https://doi.org/10.5194/se-15-1087-2024, 2024
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We detail the selection and characterization of a fault zone for earthquake experiments in the Fault Activation and Earthquake Ruptures (FEAR) project at the Bedretto Lab. FEAR, which studies earthquake processes, overcame data collection challenges near faults. The fault zone in Rotondo granite was selected based on geometry, monitorability, and hydro-mechanical properties. Remote sensing, borehole logging, and geological mapping were used to create a 3D model for precise monitoring.
Maxime Jamet, Gregory Ballas, Roger Soliva, Olivier Gerbeaud, Thierry Lefebvre, Christine Leredde, and Didier Loggia
Solid Earth, 15, 895–920, https://doi.org/10.5194/se-15-895-2024, https://doi.org/10.5194/se-15-895-2024, 2024
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At the high temperatures present in the deeper crust, minerals such as quartz can flow much like silly putty. The detailed mechanisms of how atoms are reorganized depends upon several factors, such as the temperature and the rate of which the mineral changes shape. We present observations from a naturally-deformed rock showing that the amount of water present also influences the type of deformation in quartz, with implications for geological interpretations.
Matthew S. Hodge, Guri Venvik, Jochen Knies, Roelant van der Lelij, Jasmin Schönenberger, Øystein Nordgulen, Marco Brönner, Aziz Nasuti, and Giulio Viola
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Smøla island, in the mid-Norwegian margin, has complex fracture and fault patterns resulting from tectonic activity. This study uses a multiple-method approach to unravel Smøla's tectonic history. We found five different phases of deformation related to various fracture geometries and minerals dating back hundreds of millions of years. 3D models of these features visualise these structures in space. This approach may help us to understand offshore oil and gas reservoirs hosted in the basement.
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EGUsphere, https://doi.org/10.5194/egusphere-2024-1077, https://doi.org/10.5194/egusphere-2024-1077, 2024
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Understanding the strain accumulation processes in ductile shear zones is essential to explain the failure mechanisms at great crustal depths. This study explores the rheological and kinematic factors determining the varying modes of shear accommodation in natural shear zones. Numerical simulations suggest that an interplay of the following parameters: initial bulk viscosity, bulk shear rate, and internal cohesion governs the dominance of one accommodation mechanism over the other.
Júlia Gómez-Romeu and Nick Kusznir
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We investigate the extensional fault geometry and its evolution during the stretching and thinning of continental crust and lithosphere leading to continental breakup. We focus on the fault-controlled processes that thin and rupture the final 10 km of continental crust at magma-poor margins prior to mantle exhumation. We show that isostatic fault rotation in response to extension is fundamental to understanding the formation of tectonic structures observed on seismic reflection data.
Karsten Reiter, Oliver Heidbach, and Moritz O. Ziegler
Solid Earth, 15, 305–327, https://doi.org/10.5194/se-15-305-2024, https://doi.org/10.5194/se-15-305-2024, 2024
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It is generally assumed that faults have an influence on the stress state of the Earth’s crust. It is questionable whether this influence is still present far away from a fault. Simple numerical models were used to investigate the extent of the influence of faults on the stress state. Several models with different fault representations were investigated. The stress fluctuations further away from the fault (> 1 km) are very small.
Yukinojo Koyama, Simon R. Wallis, and Takayoshi Nagaya
Solid Earth, 15, 143–166, https://doi.org/10.5194/se-15-143-2024, https://doi.org/10.5194/se-15-143-2024, 2024
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Stress along a subduction plate boundary is important for understanding subduction phenomena such as earthquakes. We estimated paleo-stress using quartz recrystallized grain size combined with deformation temperature and P–T paths of exhumed rocks. The obtained results show differential stresses of 30.8–82.7 MPa consistent over depths of 17–27 km in the paleo-subduction boundary. The obtained stress may represent the initial conditions under which slow earthquakes nucleated in the same domain.
Annelotte Weert, Kei Ogata, Francesco Vinci, Coen Leo, Giovanni Bertotti, Jerome Amory, and Stefano Tavani
Solid Earth, 15, 121–141, https://doi.org/10.5194/se-15-121-2024, https://doi.org/10.5194/se-15-121-2024, 2024
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On the road to a sustainable planet, geothermal energy is considered one of the main substitutes when it comes to heating. The geological history of an area can have a major influence on the application of these geothermal systems, as demonstrated in the West Netherlands Basin. Here, multiple episodes of rifting and subsequent basin inversion have controlled the distribution of the reservoir rocks, thus influencing the locations where geothermal energy can be exploited.
Pâmela C. Richetti, Frank Zwaan, Guido Schreurs, Renata S. Schmitt, and Timothy C. Schmid
Solid Earth, 14, 1245–1266, https://doi.org/10.5194/se-14-1245-2023, https://doi.org/10.5194/se-14-1245-2023, 2023
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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 1000 m height, allowing for studies thereof, 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.
Malte Froemchen, Ken J. W. McCaffrey, Mark B. Allen, Jeroen van Hunen, Thomas B. Phillips, and Yueren Xu
EGUsphere, https://doi.org/10.5194/egusphere-2023-2563, https://doi.org/10.5194/egusphere-2023-2563, 2023
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The Shanxi Rift is a young active rift in North China that formed superimposed on a Proterozoic orogen. The impact of these structures on the active rift faults is poorly constrained. Here we quantify the landscape response to active faulting and compare these to published maps of inherited structures. We find that inherited structures played an important role in the segmentation of the Shanxi Rift and in the development of Rift Interaction Zones, the most active regions of the Shanxi Rift.
Adam J. Cawood, Hannah Watkins, Clare E. Bond, Marian J. Warren, and Mark A. Cooper
Solid Earth, 14, 1005–1030, https://doi.org/10.5194/se-14-1005-2023, https://doi.org/10.5194/se-14-1005-2023, 2023
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Here we test conceptual models of fracture development by investigating fractures across multiple scales. We find that most fractures increase in abundance towards the fold hinge, and we interpret these as being fold related. Other fractures at the site show inconsistent orientations and are unrelated to fold formation. Our results show that predicting fracture patterns requires the consideration of multiple geologic variables.
Johanna Heeb, David Healy, Nicholas E. Timms, and Enrique Gomez-Rivas
Solid Earth, 14, 985–1003, https://doi.org/10.5194/se-14-985-2023, https://doi.org/10.5194/se-14-985-2023, 2023
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Hydration of rocks is a key process in the Earth’s crust and mantle that is accompanied by changes in physical traits and mechanical behaviour of rocks. This study assesses the influence of stress on hydration reaction kinetics and mechanics in experiments on anhydrite. We show that hydration occurs readily under stress and results in localized hydration along fractures and mechanic weakening. New gypsum growth is selective and depends on the stress field and host anhydrite crystal orientation.
Roy Helge Gabrielsen, Panagiotis Athanasios Giannenas, Dimitrios Sokoutis, Ernst Willingshofer, Muhammad Hassaan, and Jan Inge Faleide
Solid Earth, 14, 961–983, https://doi.org/10.5194/se-14-961-2023, https://doi.org/10.5194/se-14-961-2023, 2023
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The Barents Shear Margin defines the border between the relatively shallow Barents Sea that is situated on a continental plate and the deep ocean. This margin's evolution history was probably influenced by plate tectonic reorganizations. From scaled experiments, we deduced several types of structures (faults, folds, and sedimentary basins) that help us to improve the understanding of the history of the opening of the North Atlantic.
Leslie Logan, Ervin Veress, Joel B. H. Andersson, Olof Martinsson, and Tobias E. Bauer
Solid Earth, 14, 763–784, https://doi.org/10.5194/se-14-763-2023, https://doi.org/10.5194/se-14-763-2023, 2023
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The Pahtohavare Cu ± Au deposits in the Kiruna mining district have a dubious timing of formation and have not been contextualized within an up-to-date tectonic framework. Structural mapping was carried out to reveal that the deposits are hosted in brittle structures that cut a noncylindrical, SE-plunging anticline constrained to have formed during the late-Svecokarelian orogeny. These results show that Cu ± Au mineralization formed more than ca. 80 Myr after iron oxide–apatite mineralization.
Alexandra Tamas, Dan M. Tamas, Gabor Tari, Csaba Krezsek, Alexandru Lapadat, and Zsolt Schleder
Solid Earth, 14, 741–761, https://doi.org/10.5194/se-14-741-2023, https://doi.org/10.5194/se-14-741-2023, 2023
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Tectonic processes are complex and often difficult to understand due to the limitations of surface or subsurface data. One such process is inversion tectonics, which means that an area initially developed in an extension (such as the opening of an ocean) is reversed to compression (the process leading to mountain building). In this research, we use a laboratory method (analogue modelling), and with the help of a sandbox, we try to better understand structures (folds/faults) related to inversion.
Elizabeth Parker Wilson, Pablo Granado, Pablo Santolaria, Oriol Ferrer, and Josep Anton Muñoz
Solid Earth, 14, 709–739, https://doi.org/10.5194/se-14-709-2023, https://doi.org/10.5194/se-14-709-2023, 2023
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This work focuses on the control of accommodation zones on extensional and subsequent inversion in salt-detached domains using sandbox analogue models. During extension, the transfer zone acts as a pathway for the movement of salt, changing the expected geometries. When inverted, the salt layer and syn-inversion sedimentation control the deformation style in the salt-detached cover system. Three natural cases are compared to the model results and show similar inversion geometries.
Oriol Ferrer, Eloi Carola, and Ken McClay
Solid Earth, 14, 571–589, https://doi.org/10.5194/se-14-571-2023, https://doi.org/10.5194/se-14-571-2023, 2023
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Using an experimental approach based on scaled sandbox models, this work aims to understand how salt above different rotational fault blocks influences the cover geometry and evolution, first during extension and then during inversion. The results show that inherited salt structures constrain contractional deformation. We show for the first time how welds and fault welds are reopened during contractional deformation, having direct implications for the subsurface exploration of natural resources.
Chiara Montemagni, Stefano Zanchetta, Martina Rocca, Igor M. Villa, Corrado Morelli, Volkmar Mair, and Andrea Zanchi
Solid Earth, 14, 551–570, https://doi.org/10.5194/se-14-551-2023, https://doi.org/10.5194/se-14-551-2023, 2023
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The Vinschgau Shear Zone (VSZ) is one of the largest and most significant shear zones developed within the Late Cretaceous thrust stack in the Austroalpine domain of the eastern Alps. 40Ar / 39Ar geochronology constrains the activity of the VSZ between 97 and 80 Ma. The decreasing vorticity towards the core of the shear zone, coupled with the younging of mylonites, points to a shear thinning behavior. The deepest units of the Eo-Alpine orogenic wedge were exhumed along the VSZ.
Jordi Miró, Oriol Ferrer, Josep Anton Muñoz, and Gianreto Manastchal
Solid Earth, 14, 425–445, https://doi.org/10.5194/se-14-425-2023, https://doi.org/10.5194/se-14-425-2023, 2023
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Using the Asturian–Basque–Cantabrian system and analogue (sandbox) models, this work focuses on the linkage between basement-controlled and salt-decoupled domains and how deformation is accommodated between the two during extension and subsequent inversion. Analogue models show significant structural variability in the transitional domain, with oblique structures that can be strongly modified by syn-contractional sedimentation. Experimental results are consistent with the case study.
Junichi Fukuda, Takamoto Okudaira, and Yukiko Ohtomo
Solid Earth, 14, 409–424, https://doi.org/10.5194/se-14-409-2023, https://doi.org/10.5194/se-14-409-2023, 2023
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We measured water distributions in deformed quartz by infrared spectroscopy mapping and used the results to discuss changes in water distribution resulting from textural development. Because of the grain size reduction process (dynamic recrystallization), water contents decrease from 40–1750 wt ppm in host grains of ~2 mm to 100–510 wt ppm in recrystallized regions composed of fine grains of ~10 µm. Our results indicate that water is released and homogenized by dynamic recrystallization.
Bastien Walter, Yves Géraud, Alexiane Favier, Nadjib Chibati, and Marc Diraison
EGUsphere, https://doi.org/10.5194/egusphere-2023-397, https://doi.org/10.5194/egusphere-2023-397, 2023
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Lake Abhe in southwestern Djibouti is known for its exposures of massive hydrothermal chimneys and hot springs on the lake’s eastern shore. This study highlights the control of the main structural faults of the area on the development of these hydrothermal features. This work contributes to better understand hydrothermal fluid pathways in this area and may help further exploration for the geothermal development of this remarkable site.
Michael Rudolf, Matthias Rosenau, and Onno Oncken
Solid Earth, 14, 311–331, https://doi.org/10.5194/se-14-311-2023, https://doi.org/10.5194/se-14-311-2023, 2023
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Analogue models of tectonic processes rely on the reproduction of their geometry, kinematics and dynamics. An important property is fault behaviour, which is linked to the frictional characteristics of the fault gouge. This is represented by granular materials, such as quartz sand. In our study we investigate the time-dependent frictional properties of various analogue materials and highlight their impact on the suitability of these materials for analogue models focusing on fault reactivation.
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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We analysed Zechstein salt with microscopes and observed specific microstructures that indicate much faster deformation in rock salt with fine halite grains when compared to salt with larger grains. This is important because people build large cavities in the subsurface salt for energy storage or want to deposit radioactive waste inside it. When engineers and scientists use grain-size data and equations that include this mechanism, it will help to make better predictions in geological models.
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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Progression of orogenic wedges over pre-existing extensional structures is common in nature, but deciphering the spatio-temporal evolution of deformation from the geological record remains challenging. Our laboratory experiments provide insights on how horizontal stresses are transferred across a heterogeneous crust, constrain which pre-shortening conditions can either favour or hinder the reactivatation of extensional structures, and explain what implications they have on critical taper theory.
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.
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.
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