Articles | Volume 10, issue 5
Solid Earth, 10, 1757–1784, 2019
https://doi.org/10.5194/se-10-1757-2019
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Solid Earth, 10, 1757–1784, 2019
https://doi.org/10.5194/se-10-1757-2019
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
24 Oct 2019
Research article
| 24 Oct 2019
Structure of massively dilatant faults in Iceland: lessons learned from high-resolution unmanned aerial vehicle data
Christopher Weismüller et al.
Related authors
Peter Biermanns, Benjamin Schmitz, Silke Mechernich, Christopher Weismüller, Kujtim Onuzi, Kamil Ustaszewski, and Klaus Reicherter
Solid Earth, 13, 957–974, https://doi.org/10.5194/se-13-957-2022, https://doi.org/10.5194/se-13-957-2022, 2022
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We introduce two up to 7 km long normal fault scarps near the city of Bar (Montenegro). The fact that these widely visible seismogenic structures have never been described before is even less surprising than the circumstance that they apparently do not fit the tectonic setting that they are located in. By quantifying the age and movement of the newly discovered fault scarps and by partly re-interpreting local tectonics, we introduce approaches to explain how this is still compatible.
Christopher Weismüller, Rahul Prabhakaran, Martijn Passchier, Janos L. Urai, Giovanni Bertotti, and Klaus Reicherter
Solid Earth, 11, 1773–1802, https://doi.org/10.5194/se-11-1773-2020, https://doi.org/10.5194/se-11-1773-2020, 2020
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We photographed a fractured limestone pavement with a drone to compare manual and automatic fracture tracing and analyze the evolution and spatial variation of the fracture network in high resolution. We show that automated tools can produce results comparable to manual tracing in shorter time but do not yet allow the interpretation of fracture generations. This work pioneers the automatic fracture mapping of a complete outcrop in detail, and the results can be used as fracture benchmark.
Peter Biermanns, Benjamin Schmitz, Silke Mechernich, Christopher Weismüller, Kujtim Onuzi, Kamil Ustaszewski, and Klaus Reicherter
Solid Earth, 13, 957–974, https://doi.org/10.5194/se-13-957-2022, https://doi.org/10.5194/se-13-957-2022, 2022
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We introduce two up to 7 km long normal fault scarps near the city of Bar (Montenegro). The fact that these widely visible seismogenic structures have never been described before is even less surprising than the circumstance that they apparently do not fit the tectonic setting that they are located in. By quantifying the age and movement of the newly discovered fault scarps and by partly re-interpreting local tectonics, we introduce approaches to explain how this is still compatible.
Lisa Winhausen, Kavan Khaledi, Mohammadreza Jalali, Janos L. Urai, and Florian Amann
Solid Earth, 13, 901–915, https://doi.org/10.5194/se-13-901-2022, https://doi.org/10.5194/se-13-901-2022, 2022
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Triaxial compression tests at different effective stresses allow for analysing the deformation behaviour of Opalinus Clay, the potential host rock for nuclear waste in Switzerland. We conducted microstructural investigations of the deformed samples to relate the bulk hydro-mechanical behaviour to the processes on the microscale. Results show a transition from brittle- to more ductile-dominated deformation. We propose a non-linear failure envelop associated with the failure mode transition.
Sivaji Lahiri, Kitty L. Milliken, Peter Vrolijk, Guillaume Desbois, and Janos L. Urai
Solid Earth Discuss., https://doi.org/10.5194/se-2022-11, https://doi.org/10.5194/se-2022-11, 2022
Revised manuscript under review for SE
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Understanding the mechanism of mechanical compaction is important. Previous studies on mechanical compaction were mostly done 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 us a unique opportunity to study the micromechanism of mechanical compaction on natural samples.
Manuel D. Menzel, Janos L. Urai, Estibalitz Ukar, Thierry Decrausaz, and Marguerite Godard
Solid Earth Discuss., https://doi.org/10.5194/se-2021-152, https://doi.org/10.5194/se-2021-152, 2022
Revised manuscript under review for SE
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Mantle rocks can bind large quantities of carbon by reaction with CO2, but this capacity requires that fluid pathways are not clogged by carbonate. We studied mantle rocks from Oman to understand the mechanisms allowing their reaction to carbonate and quartz. Using advanced imaging techniques, we show that abundant fractures 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.
Christoph Grützner, Simone Aschenbrenner, Petra Jamšek
Rupnik, Klaus Reicherter, Nour Saifelislam, Blaž Vičič, Marko Vrabec, Julian Welte, and Kamil Ustaszewski
Solid Earth, 12, 2211–2234, https://doi.org/10.5194/se-12-2211-2021, https://doi.org/10.5194/se-12-2211-2021, 2021
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Several large strike-slip faults in western Slovenia are known to be active, but most of them have not produced strong earthquakes in historical times. In this study we use geomorphology, near-surface geophysics, and fault excavations to show that two of these faults had surface-rupturing earthquakes during the Holocene. Instrumental and historical seismicity data do not capture the strongest events in this area.
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.
Lisa Winhausen, Jop Klaver, Joyce Schmatz, Guillaume Desbois, Janos L. Urai, Florian Amann, and Christophe Nussbaum
Solid Earth, 12, 2109–2126, https://doi.org/10.5194/se-12-2109-2021, https://doi.org/10.5194/se-12-2109-2021, 2021
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An experimentally deformed sample of Opalinus Clay (OPA), which is being considered as host rock for nuclear waste in Switzerland, was studied by electron microscopy to image deformation microstructures. Deformation localised by forming micrometre-thick fractures. Deformation zones show dilatant micro-cracking, granular flow and bending grains, and pore collapse. Our model, with three different stages of damage accumulation, illustrates microstructural deformation in a compressed OPA sample.
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.
Sarah Mader, Joachim R. R. Ritter, Klaus Reicherter, and the AlpArray Working Group
Solid Earth, 12, 1389–1409, https://doi.org/10.5194/se-12-1389-2021, https://doi.org/10.5194/se-12-1389-2021, 2021
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The Albstadt Shear Zone, SW Germany, is an active rupture zone with sometimes damaging earthquakes but no visible surface structure. To identify its segmentations, geometry, faulting pattern and extension, we analyze the continuous earthquake activity in 2011–2018. We find a segmented N–S-oriented fault zone with mainly horizontal and minor vertical movement along mostly NNE- and some NNW-oriented rupture planes. The main horizontal stress is oriented NW and due to Alpine-related loading.
Elco Luijendijk, Leo Benard, Sarah Louis, Christoph von Hagke, and Jonas Kley
Solid Earth Discuss., https://doi.org/10.5194/se-2021-22, https://doi.org/10.5194/se-2021-22, 2021
Revised manuscript not accepted
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Our knowledge of the geological history of mountain belts relies strongly on thermochronometers, methods that reconstruct the temperature history of rocks found in mountain belts. Here we provide a new equation that describes the motion of rocks in a simplified, wedge-shaped representation of a mountain belt. The equation can be used to interpret thermochronometers and can help quantify the deformation, uplift and erosion history of mountain belts.
Samuel Mock, Christoph von Hagke, Fritz Schlunegger, István Dunkl, and Marco Herwegh
Solid Earth, 11, 1823–1847, https://doi.org/10.5194/se-11-1823-2020, https://doi.org/10.5194/se-11-1823-2020, 2020
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Based on thermochronological data, we infer thrusting along-strike the northern rim of the Central Alps between 12–4 Ma. While the lithology influences the pattern of thrusting at the local scale, we observe that thrusting in the foreland is a long-wavelength feature occurring between Lake Geneva and Salzburg. This coincides with the geometry and dynamics of the attached lithospheric slab at depth. Thus, thrusting in the foreland is at least partly linked to changes in slab dynamics.
Christopher Weismüller, Rahul Prabhakaran, Martijn Passchier, Janos L. Urai, Giovanni Bertotti, and Klaus Reicherter
Solid Earth, 11, 1773–1802, https://doi.org/10.5194/se-11-1773-2020, https://doi.org/10.5194/se-11-1773-2020, 2020
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We photographed a fractured limestone pavement with a drone to compare manual and automatic fracture tracing and analyze the evolution and spatial variation of the fracture network in high resolution. We show that automated tools can produce results comparable to manual tracing in shorter time but do not yet allow the interpretation of fracture generations. This work pioneers the automatic fracture mapping of a complete outcrop in detail, and the results can be used as fracture benchmark.
Heijn van Gent and Janos L. Urai
Solid Earth, 11, 513–526, https://doi.org/10.5194/se-11-513-2020, https://doi.org/10.5194/se-11-513-2020, 2020
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Faults form due to stresses caused by crustal processes. As faults influence the stress field locally, fault interaction leads to local variations in the stress field, but this is difficult to observe directly.
We describe an outcrop of one fault abuting into another one. By careful measurement of structures in the overlapping deformation zones and separating them using published relative age data, we show a rotation in the local stress field resulting from the faults growing to each other
Mark G. Rowan, Janos L. Urai, J. Carl Fiduk, and Peter A. Kukla
Solid Earth, 10, 987–1013, https://doi.org/10.5194/se-10-987-2019, https://doi.org/10.5194/se-10-987-2019, 2019
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Ancient evaporite sequences were deposited as interlayered rocksalt, other evaporites, and non-evaporite rocks that have enormous differences in strength. Whereas the ductile layers flow during deformation, strong layers are folded and/or torn apart, with the intrasalt deformation dependent on the mode and history of salt tectonics. This has important implications for accurately imaging and interpreting subsurface seismic data and for drilling wells through evaporite sequences.
Sajid Ali, Peter Biermanns, Rashid Haider, and Klaus Reicherter
Nat. Hazards Earth Syst. Sci., 19, 999–1022, https://doi.org/10.5194/nhess-19-999-2019, https://doi.org/10.5194/nhess-19-999-2019, 2019
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The Karakoram Highway (KKH) is an important physical connection between Pakistan and China. Landslides have been a major threat to its stability since its construction. After the announcement of the China–Pakistan Economic Corridor (CPEC), KKH has had more importance. Geoscientists from research institutions in both countries are assessing landslide hazard and risk along the highway. In a PhD project, this paper will be followed by a detailed analysis of mass movements along the highway.
Samuel Mock, Christoph von Hagke, Fritz Schlunegger, István Dunkl, and Marco Herwegh
Solid Earth Discuss., https://doi.org/10.5194/se-2019-56, https://doi.org/10.5194/se-2019-56, 2019
Revised manuscript not accepted
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Based on own and published age data, we can infer tectonic pulses along-strike the entire northern rim of the Central Alps between 12–4 million years. Although lithologic variations largely influence the local deformation pattern, the tectonic signal is remarkably consistent all the way from Lake Geneva to Salzburg. This might result from a deep-seated tectonic force and marks a change from dominantly vertical to large-scale horizontal tectonics in the late stage of Alpine orogeny.
Arne Grobe, Christoph von Hagke, Ralf Littke, István Dunkl, Franziska Wübbeler, Philippe Muchez, and Janos L. Urai
Solid Earth, 10, 149–175, https://doi.org/10.5194/se-10-149-2019, https://doi.org/10.5194/se-10-149-2019, 2019
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The Mesozoic sequences of the Oman mountains experienced only weak post-obduction overprint and deformation, and thus they offer a unique natural laboratory to study obduction. We present a study of pressure and temperature evolution in the passive continental margin under the Oman Ophiolite using numerical basin models calibrated with thermal maturity data, fluid-inclusion thermometry, and low-temperature thermochronology.
Ismay Vénice Akker, Josef Kaufmann, Guillaume Desbois, Jop Klaver, Janos L. Urai, Alfons Berger, and Marco Herwegh
Solid Earth, 9, 1141–1156, https://doi.org/10.5194/se-9-1141-2018, https://doi.org/10.5194/se-9-1141-2018, 2018
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We studied porosity changes of slates from eastern Switzerland, which were deposited in an ocean in front of the emerging Alps during the Cenozoic. The Alpine collision between the European and African plates brought the rocks from this basin to today’s position in the Alps. From the basin to the surface, the porosity first decreased down to a small number of round cavities (<1 vol%) to microfractures, and once at the surface, the porosity increased again due to the formation of macro-fractures.
Simon Virgo, Christoph von Hagke, and Janos L. Urai
Solid Earth, 9, 91–113, https://doi.org/10.5194/se-9-91-2018, https://doi.org/10.5194/se-9-91-2018, 2018
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The marbles of the migmatitic dome on the island Naxos contain deformed layers of amphibolite with multiple phases of boudinage. The boudins formed by E–W shortening normal to the layers and layer parallel extension in various directions. We identified five different generations of boudins that show that E–W shortening is the prevalent deformation in these rocks during the peak metamorphosis and the following cooling, different from other parts of the island dominated by top-to-north shearing.
Ben Laurich, Janos L. Urai, Christian Vollmer, and Christophe Nussbaum
Solid Earth, 9, 1–24, https://doi.org/10.5194/se-9-1-2018, https://doi.org/10.5194/se-9-1-2018, 2018
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In Switzerland, the Opalinus Clay (OPA) formation is favored to host a repository for nuclear waste. Thus, we must know its deformation behavior. In this study, we focused on the microstructure of gouge, a thin (< 2 cm), drastically strained clay layer at the so-called Main Fault in the Mont Terri rock laboratory. We suggest that in situ gouge deforms in a more viscous manner than undeformed OPA in laboratory conditions. Moreover, we speculate about the origin and evolution of the gouge layer.
Guillaume Desbois, Nadine Höhne, Janos L. Urai, Pierre Bésuelle, and Gioacchino Viggiani
Solid Earth, 8, 291–305, https://doi.org/10.5194/se-8-291-2017, https://doi.org/10.5194/se-8-291-2017, 2017
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This work integrates measurements of the mechanical and transport properties with microstructures to understand deformation mechanisms in cemented mudrock. Cataclastic mechanisms are dominant down to nanometre scale. At low strain the fabric contains recognizable open fractures, while at high strain the reworked clay gouge shows resealing of initial fracture porosity. In the future, it will provide a microphysical basis for constitutive models to improve their extrapolation for long timescales.
Ben Laurich, Janos L. Urai, and Christophe Nussbaum
Solid Earth, 8, 27–44, https://doi.org/10.5194/se-8-27-2017, https://doi.org/10.5194/se-8-27-2017, 2017
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Scaly clay is a well-known rock fabric that can develop in tectonic systems and that can alter the physical rock properties of a formation. However, the internal microstructure and evolution of this fabric remain poorly understood. We examined the scaly microstructure of progressively faulted Opalinus Clay using optical as well as scanning electron microscopy. We show that as little as 1 vol.% in scaly clay aggregates is strained and present an evolutionary model for this.
Michael Kettermann, Christoph von Hagke, Heijn W. van Gent, Christoph Grützner, and Janos L. Urai
Solid Earth, 7, 843–856, https://doi.org/10.5194/se-7-843-2016, https://doi.org/10.5194/se-7-843-2016, 2016
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We present an analogue modeling study on the interaction of pre-existing joints and normal faults using cohesive powder. We vary the angle between joints and a rigid basement fault and analyze interpreted map-view photographs at maximum displacement for various parameters and compare to nature. Results show a clear effect of increasing angle between joints and faults on fault geometry, fracture density and connectivity. These information can help interpreting fractured layers in the subsurface.
Michael Kettermann, Sebastian Thronberens, Oscar Juarez, Janos Lajos Urai, Martin Ziegler, Sven Asmus, and Ulrich Krüger
Solid Earth, 7, 789–815, https://doi.org/10.5194/se-7-789-2016, https://doi.org/10.5194/se-7-789-2016, 2016
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We present exceptional 3-D outcrop data of clay smears in freshly cut trenches of Miocene unconsolidated deltaic clay–sand sequences in an active lignite quarry in the Lower Rhine Embayment. We aim to identify and investigate processes that entrain clay into a fault or breach of formed clay smear. We show the importance of host rock deformation, grain-scale mixing and source layering on clay smear geometry by providing 2-D cross sections and 3-D thickness data of complete clay smear sequences.
Sascha Schneiderwind, Jack Mason, Thomas Wiatr, Ioannis Papanikolaou, and Klaus Reicherter
Solid Earth, 7, 323–340, https://doi.org/10.5194/se-7-323-2016, https://doi.org/10.5194/se-7-323-2016, 2016
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Palaeoseismological research uses historical earthquakes to verify seismic hazard assessment. Earthquakes of magnitude M > 5.5 likely produce surface ruptures that can be preserved in the subsurface. Buried soils or progressive displacements are the main targets of trenching studies. However, the recognition of these features is challenging for inexperienced researchers. Here a workflow is presented which applies remote sensing and geophysical techniques to verify layer distinction.
A. F. Raith, F. Strozyk, J. Visser, and J. L. Urai
Solid Earth, 7, 67–82, https://doi.org/10.5194/se-7-67-2016, https://doi.org/10.5194/se-7-67-2016, 2016
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3D seismic and well data were used to study the evolution of salt pillows with extreme mechanical stratification to gain a better understanding of layered evaporite deposits. During evaporation an active basement graben caused the local accumulation of thick K-Mg salts. The resulting structure after the following extensional and compressional salt flow was strongly influenced by folding of the ruptured ZIII-AC stringer, leading to thickening and internal deformation of the soft K-Mg salt layers.
M. Kettermann, C. Grützner, H. W. van Gent, J. L. Urai, K. Reicherter, and J. Mertens
Solid Earth, 6, 839–855, https://doi.org/10.5194/se-6-839-2015, https://doi.org/10.5194/se-6-839-2015, 2015
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This paper combines fieldwork, ground-penetrating radar (GPR) and remote sensing in the jointed and faulted grabens area of Canyonlands National Park, Utah, USA. GPR profiles show that graben floors are subject to faulting, although the surface shows no scarps. We enhance evidence for the effect of preexisting joints on the formation of dilatant faults and provide a conceptual model for graben evolution. Correlating paleosols from outcrops and GPR adds to estimates of the age of the grabens.
M. Kehl, E. Eckmeier, S. O. Franz, F. Lehmkuhl, J. Soler, N. Soler, K. Reicherter, and G.-C. Weniger
Clim. Past, 10, 1673–1692, https://doi.org/10.5194/cp-10-1673-2014, https://doi.org/10.5194/cp-10-1673-2014, 2014
B. Wagner, T. Wilke, S. Krastel, G. Zanchetta, R. Sulpizio, K. Reicherter, M. J. Leng, A. Grazhdani, S. Trajanovski, A. Francke, K. Lindhorst, Z. Levkov, A. Cvetkoska, J. M. Reed, X. Zhang, J. H. Lacey, T. Wonik, H. Baumgarten, and H. Vogel
Sci. Dril., 17, 19–29, https://doi.org/10.5194/sd-17-19-2014, https://doi.org/10.5194/sd-17-19-2014, 2014
Related subject area
Subject area: Tectonic plate interactions, magma genesis, and lithosphere deformation at all scales | Editorial team: Structural geology and tectonics, paleoseismology, rock physics, experimental deformation | Discipline: Structural geology
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Fault interpretation uncertainties using seismic data, and the effects on fault seal analysis: a case study from the Horda Platform, with implications for CO2 storage
Reply to Norini and Groppelli's comment on “Estimating the depth and evolution of intrusions at resurgent calderas: Los Humeros (Mexico)” by Urbani et al. (2020)
Emplacement of “exotic” Zechstein slivers along the inverted Sontra Graben (northern Hessen, Germany): clues from balanced cross sections and geometrical forward modeling
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On a new robust workflow for the statistical and spatial analysis of fracture data collected with scanlines (or the importance of stationarity)
Micro- and nano-porosity of the active Alpine Fault zone, New Zealand
Unraveling the origins and P-T-t evolution of the allochthonous Sobrado unit (Órdenes Complex, NW Spain) using combined U–Pb titanite, monazite and zircon geochronology and rare-earth element (REE) geochemistry
Fracture attribute scaling and connectivity in the Devonian Orcadian Basin with implications for geologically equivalent sub-surface fractured reservoirs
Structural control on fluid flow and shallow diagenesis: insights from calcite cementation along deformation bands in porous sandstones
The growth of faults and fracture networks in a mechanically evolving, mechanically stratified rock mass: a case study from Spireslack Surface Coal Mine, Scotland
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Extension and inversion of salt-bearing rift systems
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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.
Jin Lai, Dong Li, Yong Ai, Hongkun Liu, Deyang Cai, Kangjun Chen, Yuqiang Xie, and Guiwen Wang
Solid Earth Discuss., https://doi.org/10.5194/se-2021-85, https://doi.org/10.5194/se-2021-85, 2021
Revised manuscript accepted for SE
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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 presences of fracture.
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.
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.
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.
Jef Deckers, Bernd Rombaut, Koen Van Noten, and Kris Vanneste
Solid Earth, 12, 345–361, https://doi.org/10.5194/se-12-345-2021, https://doi.org/10.5194/se-12-345-2021, 2021
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This study shows the presence of two structural domains in the western border fault system of the Roer Valley graben. These domains, dominated by NW–SE-striking faults, displayed distinctly different strain distributions during both Late Cretaceous compression and Cenozoic extension. The southern domain is characterized by narrow, localized faulting, while the northern domain is characterized by wide, distributed faulting. The non-colinear WNW–ESE Grote Brogel fault links both domains.
José Piquer, Orlando Rivera, Gonzalo Yáñez, and Nicolás Oyarzún
Solid Earth, 12, 253–273, https://doi.org/10.5194/se-12-253-2021, https://doi.org/10.5194/se-12-253-2021, 2021
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A proper recognition of deep, long-lived fault systems is very important for society. They can produce potentially dangerous earthquakes. They can also act as pathways for magmas and hydrothermal fluids, leading to the formation of volcanoes, geothermal systems and mineral deposits. However, the manifestations of these very old faults in the present-day surface can be very subtle. Here, we present a detailed, multi-disciplinary study of a fault system of this type in the Andes of central Chile.
Antonin Bilau, Yann Rolland, Stéphane Schwartz, Nicolas Godeau, Abel Guihou, Pierre Deschamps, Benjamin Brigaud, Aurélie Noret, Thierry Dumont, and Cécile Gautheron
Solid Earth, 12, 237–251, https://doi.org/10.5194/se-12-237-2021, https://doi.org/10.5194/se-12-237-2021, 2021
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As a result of the collision between the European and Apulian plates, the Alps have experienced several evolutionary stages. The Penninic frontal thrust (PFT) (major thrust) was associated with compression, and now seismic studies show ongoing extensional activity. Calcite mineralization associated with shortening and extensional structures was sampled. The last deformation stages are dated by U–Pb on calcite at ~ 3.5 and ~ 2.5 Ma. Isotope analysis evidences deep crustal fluid mobilization.
Kathryn E. Elphick, Craig R. Sloss, Klaus Regenauer-Lieb, and Christoph E. Schrank
Solid Earth, 12, 141–170, https://doi.org/10.5194/se-12-141-2021, https://doi.org/10.5194/se-12-141-2021, 2021
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We analysed a sedimentary rock package located in Castlepoint, New Zealand, to test the control of the tectonic setting on the observed deformation structures. In extension and contraction, we observed faults and small fault-like structures characterised by complex spatial patterns and a reduction in porosity and grain size compared with the host rock. With these properties, the structures are likely to act as barriers to fluid flow and cause compartmentalisation of the sedimentary sequence.
Penelope I. R. Wilson, Robert W. Wilson, David J. Sanderson, Ian Jarvis, and Kenneth J. W. McCaffrey
Solid Earth, 12, 95–117, https://doi.org/10.5194/se-12-95-2021, https://doi.org/10.5194/se-12-95-2021, 2021
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Magma accommodation in the shallow crust leads to deformation of the surrounding host rock through the creation of faults, fractures and folds. This deformation will impact fluid flow around intrusive magma bodies (including sills and laccoliths) by changing the porosity and permeability network of the host rock. The results may have important implications for industries where fluid flow within the subsurface adds value (e.g. oil and gas, hydrology, geothermal and carbon sequestration).
Martin Balcewicz, Benedikt Ahrens, Kevin Lippert, and Erik H. Saenger
Solid Earth, 12, 35–58, https://doi.org/10.5194/se-12-35-2021, https://doi.org/10.5194/se-12-35-2021, 2021
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The geothermal potential of a carbonate reservoir in the Rhine-Ruhr area, Germany, was investigated by field and laboratory investigations. The carbonate layer of interest is approx. 150 m thick; located at 4 to 6 km depth; and might extend below Essen, Bochum, and Dortmund. We proposed focusing on discontinuities striking NNW–SSE for geothermal applications, as these are the most common, strike in the direction of the main horizontal stress, and dominate reservoir fluid flow.
Andrea Bistacchi, Silvia Mittempergher, Mattia Martinelli, and Fabrizio Storti
Solid Earth, 11, 2535–2547, https://doi.org/10.5194/se-11-2535-2020, https://doi.org/10.5194/se-11-2535-2020, 2020
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We present an innovative workflow for the statistical analysis of fracture data collected along scanlines. Our methodology is based on performing non-parametric statistical tests, which allow detection of important features of the spatial distribution of fractures, and on the analysis of the cumulative spacing function (CSF) and cumulative spacing derivative (CSD), which allows the boundaries of stationary domains to be defined in an objective way.
Martina Kirilova, Virginia Toy, Katrina Sauer, François Renard, Klaus Gessner, Richard Wirth, Xianghui Xiao, and Risa Matsumura
Solid Earth, 11, 2425–2438, https://doi.org/10.5194/se-11-2425-2020, https://doi.org/10.5194/se-11-2425-2020, 2020
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Processes associated with open pores can change the physical properties of rocks and cause earthquakes. In borehole samples from the Alpine Fault zone, we show that many pores in these rocks were filled by weak materials that can slide easily. The amount of open spaces was thus reduced, and fluids circulating within them built up high pressures. Both weak materials and high pressures within pores reduce the rock strength; thus the state of pores here can trigger the next Alpine Fault earthquake.
José Manuel Benítez-Pérez, Pedro Castiñeiras, Juan Gómez-Barreiro, José R. Martínez Catalán, Andrew Kylander-Clark, and Robert Holdsworth
Solid Earth, 11, 2303–2325, https://doi.org/10.5194/se-11-2303-2020, https://doi.org/10.5194/se-11-2303-2020, 2020
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The Sobrado unit represents an allochthonous tectonic slice of exhumed high-grade metamorphic rocks formed during a complex sequence of orogenic processes in the middle to lower crust. We have combined U–Pb geochronology and REE analyses (LASS-ICP-MS) of accessory minerals in migmatitic paragneiss (monazite, zircon) and mylonitic amphibolites (titanite) to constrain the evolution. A Middle Devonian minimum age for HP metamorphism has been obtained.
Anna M. Dichiarante, Ken J. W. McCaffrey, Robert E. Holdsworth, Tore I. Bjørnarå, and Edward D. Dempsey
Solid Earth, 11, 2221–2244, https://doi.org/10.5194/se-11-2221-2020, https://doi.org/10.5194/se-11-2221-2020, 2020
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We studied the characteristics of fracture systems in the Devonian rocks of the Orcadian Basin in Caithness. These mineral-filled fractures have properties that may be used to predict the size and spatial arrangement of similar structures in offshore basins. This includes the Clair field in the Faroe–Shetland Basin.
Leonardo Del Sole, Marco Antonellini, Roger Soliva, Gregory Ballas, Fabrizio Balsamo, and Giulio Viola
Solid Earth, 11, 2169–2195, https://doi.org/10.5194/se-11-2169-2020, https://doi.org/10.5194/se-11-2169-2020, 2020
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This study focuses on the impact of deformation bands on fluid flow and diagenesis in porous sandstones in two different case studies (northern Apennines, Italy; Provence, France) by combining a variety of multiscalar mapping techniques, detailed field and microstructural observations, and stable isotope analysis. We show that deformation bands buffer and compartmentalize fluid flow and foster and localize diagenesis, recorded by carbonate cement nodules spatially associated with the bands.
Billy James Andrews, Zoe Kai Shipton, Richard Lord, and Lucy McKay
Solid Earth, 11, 2119–2140, https://doi.org/10.5194/se-11-2119-2020, https://doi.org/10.5194/se-11-2119-2020, 2020
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Through geological mapping we find that fault zone internal structure depends on whether or not the fault cuts multiple lithologies, the presence of shale layers, and the orientation of joints and coal cleats at the time of faulting. During faulting, cementation of fractures (i.e. vein formation) is highest where the fractures are most connected. This leads to the counter-intuitive result that the highest-fracture-density part of the network often has the lowest open-fracture connectivity.
Nicolas Mansard, Holger Stünitz, Hugues Raimbourg, Jacques Précigout, Alexis Plunder, and Lucille Nègre
Solid Earth, 11, 2141–2167, https://doi.org/10.5194/se-11-2141-2020, https://doi.org/10.5194/se-11-2141-2020, 2020
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Our rock deformation experiments (solid-medium Griggs-type apparatus) on wet assemblages of mafic compositions show that the ability of minerals to react controls the portions of rocks that deform and that minor chemical and mineralogical variations can considerably modify the strength of deformed assemblages. Our study suggests that the rheology of mafic rocks, which constitute a large part of the oceanic crust, cannot be summarized as being rheologically controlled by monophase materials.
Vladimir Shipilin, David C. Tanner, Hartwig von Hartmann, and Inga Moeck
Solid Earth, 11, 2097–2117, https://doi.org/10.5194/se-11-2097-2020, https://doi.org/10.5194/se-11-2097-2020, 2020
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In our work, we carry out an in-depth structural analysis of a geometrically decoupled fault system in the southern German Molasse Basin using a high-resolution 3-D seismic dataset. Based on this analysis, we reconstruct the tectonic history and changes in the stress regimes to explain the structure and evolution of faults. The results contribute in understanding the driving mechanisms behind formation, propagation, and reactivation of faults during foreland basin formation.
Nick M. W. Roberts, Jack K. Lee, Robert E. Holdsworth, Christopher Jeans, Andrew R. Farrant, and Richard Haslam
Solid Earth, 11, 1931–1945, https://doi.org/10.5194/se-11-1931-2020, https://doi.org/10.5194/se-11-1931-2020, 2020
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We characterise a well-known fractured and faulted exposure of Cretaceous chalk in NE England, combining field observations with novel U–Pb calcite dating. We show that the faulting and associated fluid flow occurred during the interval of ca. 64–56 Ma, predating earlier estimates of Alpine-related tectonic inversion. We demonstrate that the main extensional fault zone acted as a conduit linking voluminous fluid flow and linking deeper sedimentary layers with the shallow subsurface.
Elizabeth S. Petrie, Kelly K. Bradbury, Laura Cuccio, Kayla Smith, James P. Evans, John P. Ortiz, Kellie Kerner, Mark Person, and Peter Mozley
Solid Earth, 11, 1803–1821, https://doi.org/10.5194/se-11-1803-2020, https://doi.org/10.5194/se-11-1803-2020, 2020
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A summary of observed rock properties across the contact between crystalline basement rock and the overlying younger sedimentary rocks from outcrop and core samples is presented. The data span a range of tectonic settings and describe the rock types immediately adjacent to the contact. The range of features observed at these contacts can influence the migration of fluids. The observations presented here are critical for the safe implementation of fluid injection and geothermal production.
Christopher Weismüller, Rahul Prabhakaran, Martijn Passchier, Janos L. Urai, Giovanni Bertotti, and Klaus Reicherter
Solid Earth, 11, 1773–1802, https://doi.org/10.5194/se-11-1773-2020, https://doi.org/10.5194/se-11-1773-2020, 2020
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We photographed a fractured limestone pavement with a drone to compare manual and automatic fracture tracing and analyze the evolution and spatial variation of the fracture network in high resolution. We show that automated tools can produce results comparable to manual tracing in shorter time but do not yet allow the interpretation of fracture generations. This work pioneers the automatic fracture mapping of a complete outcrop in detail, and the results can be used as fracture benchmark.
I. Tonguç Uysal, Claudio Delle Piane, Andrew James Todd, and Horst Zwingmann
Solid Earth, 11, 1653–1679, https://doi.org/10.5194/se-11-1653-2020, https://doi.org/10.5194/se-11-1653-2020, 2020
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This study represents an integrated approach to radiometric age dating using potassium-bearing clay minerals formed during faulting and provides insights into the enigmatic time–space distribution of Precambrian tectonic zones in north-central Australia. Specifically, our work firmly indicates a late Mesoproterzoic minimum age for the Millungera Basin in north Australia and a previously unrecorded concealed late Mesoproterozoic–early Neoproterozoic tectonic event in north-central Australia.
Stefano Tavani, Pablo Granado, Amerigo Corradetti, Thomas Seers, Josep Maria Casas, and Josep Anton Muñoz
Solid Earth, 11, 1643–1651, https://doi.org/10.5194/se-11-1643-2020, https://doi.org/10.5194/se-11-1643-2020, 2020
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Using orthophotos, we manually digitized 30 000 joints in the eastern Ebro Basin of the Pyrenees. Joints are perpendicular to the belt in the frontal portion of the belt and in the inner and central portion of the foredeep basin. Joint orientations in the external portion of the foredeep become less clustered. Joints in the studied area formed in the foredeep in response to foredeep-parallel stretching, which becomes progressively less intense within the external portion of the foredeep basin.
Thomas B. Phillips, Christopher A.-L. Jackson, and James R. Norcliffe
Solid Earth, 11, 1489–1510, https://doi.org/10.5194/se-11-1489-2020, https://doi.org/10.5194/se-11-1489-2020, 2020
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Normal faults often reactivate under compression, in a process called inversion. The 3D geometry of these structures (and the effect on resultant inversion structural style) is often not considered. Using seismic reflection data, we examine how stresses form different inversion styles that are controlled by the geometry of the pre-existing structure. Geometrically simple faults are preferentially reactivated; more complex areas are typically not reactivated and instead experience bulk uplift.
Ashton Krajnovich, Wendy Zhou, and Marte Gutierrez
Solid Earth, 11, 1457–1474, https://doi.org/10.5194/se-11-1457-2020, https://doi.org/10.5194/se-11-1457-2020, 2020
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In this paper, a novel methodology of 3D geologic model uncertainty assessment that considers both input data and prior knowledge is developed and applied to characterize fault zones – areas of damaged rock surrounding a fault surface that are important to subsurface engineering projects. The results of the study demonstrate how existing frameworks can be expanded to incorporate new types of information to arrive at a realistic and straightforward model of fault zone geometry in the subsurface.
Sreyashi Bhowmick and Tridib Kumar Mondal
Solid Earth, 11, 1227–1246, https://doi.org/10.5194/se-11-1227-2020, https://doi.org/10.5194/se-11-1227-2020, 2020
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We explore pre-existing fabric in metabasalts replete with a wide range of crisscross fractures/faults, hosting quartz veins of variable orientations and thicknesses in the Chitradurga region, India. The fractures are identified as components of a riedel shear system. We evaluate reactivation potential of fractures and conclude that episodic changes in fluid pressure conditions triggered fault-valve action, thereby reactivating fabric and fractures, leading to vein emplacement in the region.
Tim P. Dooley and Michael R. Hudec
Solid Earth, 11, 1187–1204, https://doi.org/10.5194/se-11-1187-2020, https://doi.org/10.5194/se-11-1187-2020, 2020
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Sandbox models investigated extension and inversion of salt-bearing rifts such as those found in the Moroccan High Atlas, North Africa. Sand packs were stretched and the structural lows were filled with a salt analog. Models were then subjected to additional extension and loading that remobilized the salt into diapirs. During shortening the distribution of the salt in the overburden governed the structural styles and trends in the supra-salt strata, strongly decoupled from subsalt deformation.
Christopher A.-L. Jackson, Paul S. Whipp, Robert L. Gawthorpe, and Matthew M. Lewis
Solid Earth, 11, 1027–1051, https://doi.org/10.5194/se-11-1027-2020, https://doi.org/10.5194/se-11-1027-2020, 2020
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Plate tectonics describes the creation, motion, and ultimate destruction of the Earth's continents and oceans. A key plate tectonic process is continental extension; this occurs when the Earth's plates are pulled apart to ultimately form a new ocean. Giant fractures (faults) accommodate plate stretching, although buckling (folding) is thought to be locally important. We use field data to understand how fracturing and buckling relate to each other, demonstrating they are spatially complex.
Efstratios Delogkos, Muhammad Mudasar Saqab, John J. Walsh, Vincent Roche, and Conrad Childs
Solid Earth, 11, 935–945, https://doi.org/10.5194/se-11-935-2020, https://doi.org/10.5194/se-11-935-2020, 2020
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Normal faults have irregular geometries on a range of scales. A quantitative model has been presented which illustrates the range of deformation arising from movement on fault surface irregularities, with fault-bend folding generating geometries reminiscent of normal drag and reverse drag. We show that fault throw can be subject to errors of up to ca. 50 % for realistic fault bend geometries (up to ca. 40°), even on otherwise sub-planar faults with constant displacement.
David A. Ferrill, Kevin J. Smart, and Alan P. Morris
Solid Earth, 11, 899–908, https://doi.org/10.5194/se-11-899-2020, https://doi.org/10.5194/se-11-899-2020, 2020
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This paper explores failure modes and deformation behavior of faults in the mechanically layered Eagle Ford Formation, an ultra-low permeability self-sourced oil and gas reservoir and aquitard in southwest Texas, USA. The role of dilation versus slip relates in predictable ways to mechanical stratigraphy, stress field, and dilation and slip tendency. We conclude that dilation tendency vs. slip tendency can be used to infer fault and fracture deformation modes and conduit versus seal behaviour.
Raúl Pérez-López, José F. Mediato, Miguel A. Rodríguez-Pascua, Jorge L. Giner-Robles, Adrià Ramos, Silvia Martín-Velázquez, Roberto Martínez-Orío, and Paula Fernández-Canteli
Solid Earth, 11, 719–739, https://doi.org/10.5194/se-11-719-2020, https://doi.org/10.5194/se-11-719-2020, 2020
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Long-term monitoring of CO2 of onshore storage has to consider thousands of years as a medium lifetime of the storage. In this wide time interval, the stress and strain properties of the reservoir change and earthquakes could occur. Therefore, we have to identify those fault sets which can be reactivated by changing the stress conditions. We need to know the role of active fault sets and model the changing conditions to prevent induced seismicity.
Joel B. H. Andersson, Tobias E. Bauer, and Edward P. Lynch
Solid Earth, 11, 547–578, https://doi.org/10.5194/se-11-547-2020, https://doi.org/10.5194/se-11-547-2020, 2020
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In this field-based study, geological structures and hydrothermal alterations in one of the least known geological terrains in Sweden are investigated. The area is located above the polar circle in northwestern Sweden that produces a significant portion of the iron and copper in the EU. A new tectonic model based on field evidence and microstructures is presented and it is shown that minerals typical for iron and copper–gold deposits can be linked to different phases of the structural evolution.
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Short summary
We use drones to study surface geometries of massively dilatant faults (MDFs) in Iceland, with apertures up to tens of meters at the surface. Based on throw, aperture and structures, we define three geometrically different endmembers of the surface expression of MDFs and show that they belong to one continuum. The transition between the endmembers is fluent and can change at one fault over short distances, implying less distinct control of deeper structures on surface geometries than expected.
We use drones to study surface geometries of massively dilatant faults (MDFs) in Iceland, with...
