Jonas B Ruh

Jonas B Ruh
ETH Zurich | ETH Zürich · Department of Earth Sciences

PhD

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61
Publications
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763
Citations

Publications

Publications (61)
Article
Full-text available
Many fossil and active accretionary wedge systems show signs of tectonic underplating, which denotes accretion of underthrust material to the base of the wedge. Underplating is a viable process for thickening of the rear part of accretionary wedges, for example as a response to horizontal growth perpendicular to strike. Here, numerical experiments...
Article
For progressively deforming multi-phase aggregates, it is unclear to what extent the change in geometry and orientation of the involved phases leads to textural strain weakening and thus may control strain localization. Consequently, the question arises how the ductile flow of multi-phase rocks can be described or determined. To contribute to the u...
Article
Full-text available
The unlined Bedretto tunnel crosses large parts of the pre-Triassic basement of the Gotthard massif (Central Alps), giving the possibility to study late-Variscan plutonic rocks (Rotondo granite) and their Caledonian (poly-)metamorphic host rocks (Tremola and Prato series). The Rotondo granite consists mostly of an equigranular, fine-grained granite...
Article
Full-text available
Variation in the effective strength of the lithosphere allows for active plate tectonics and is permitted by different deformation mechanisms operating in the crust and upper mantle. The dominant mechanisms are debated, but geodynamic models often employ grain-size-independent mechanisms or evaluate a single grain size. However, observations from n...
Preprint
Full-text available
Geodynamic numerical models often employ solely grain-size-independent dislocation creep to describe upper mantle dynamics. However, observations from nature and rock deformation experiments suggest that shear zones can transition to a grain-size-dependent creep mechanism due to dynamic grain size evolution, with important implications for the over...
Conference Paper
Full-text available
We present a 2D p-wave velocity (Vp) model and a coincident multichannel seismic reflection profile mapping the structure of the southern Costa Rica margin and incoming Cocos Ridge. The seismic profiles image the ocean and overriding plates from the trench across the entire offshore margin, including the structures involved in the 2002 Mw6.4 Osa ea...
Article
Full-text available
We present a series of 2D thermo-mechanical numerical experiments of thick-skinned crustal extension including a pre-rift salt horizon and subsequent thin-, thick-skinned, or mixed styles of convergence accompanied by surface processes. Extension localization along steep basement faults produces half-graben structures and leads to variations in the...
Article
The integration of biostratigraphy, strontium isotope stratigraphy, and magnetostratigraphy allowed for the precise dating of the >3.0-km-thick marine to non-marine foreland sedimentary succession within the Dowlatabad growth syncline along the Frontal Fars arc in the Zagros Fold Belt that extends from eastern Turkey to southern Iran. This area was...
Article
Full-text available
Orogenic wedges commonly display an inner wedge, where crystalline units have been exhumed, and an outer wedge formed by imbricated sedimentary units detached from the basement. Analog experiments have shown that similar structures can emerge naturally in presence of weak décollements due to the interplay between erosion and deformation. In this st...
Data
Short video (GIF format) showing the evolution of shale minibasins atop of the Miocene giant olistostrome in Western Makran (Iran).
Article
In this work we study the dynamics of double subduction systems with opposite polarity in adjacent segments. A combined approach of numerical and analog experiments allows us to compare results and exploit the strengths of both methodologies. High‐resolution numerical experiments complement laboratory results by providing quantities difficult to me...
Conference Paper
Full-text available
This work presents numerical experiments of contractional rejuvenation of passive margin minibasins and related diapiric structures and the involvement in inverted rift and fold-and-thrust belt systems. We use 2D finite difference numerical experiments with a temperature-dependent Maxwell-type visco-elasto-plastic rheology. Our experiments consist...
Article
Full-text available
We present a 2‐D P wave velocity model and a coincident multichannel seismic reflection profile characterizing the structure of the southern Costa Rica margin and incoming Cocos Ridge. The seismic profiles image the ocean and overriding plates from the trench across the entire offshore margin, including the structures involved in the 2002 Osa earth...
Article
The Dehdasht Basin, a small structural basin located in the southeast of the Dezful Embayment in the Zagros fold-and-thrust belt, has a complex tectonic structure characterized by both compressional and halokinetic features. 2D numerical models are used to test how geometrical and rheological parameters affected the Miocene-Pliocene evolution of th...
Article
The Kopet Dagh Mountains in NE Iran result from Cenozoic tectonic inversion of Triassic and Jurassic rifts that formed along the southern margin of the Eurasian continental plate. The Kopet Dagh defines an arcuate orogen leading to the suggestion that oroclinal bending took place during its formation. We performed a paleomagnetic study including se...
Article
In many mountain belts, deformation concentrates along mechanically weak fault zones inherited from earlier tectonic events. This work investigates the effects of two modes of structural weakening on the orientation of rifting and later tectonic inversion with respect to the imposed divergence/convergence direction in a high-resolution 3D finite di...
Article
This work presents numerical experiments of inversion of rift basins and consequent sub-thrust imbrication in tectonic wedges. Half-graben basins initially develop and then are covered with a post-rift sequence bearing a décollement-prone horizon (i.e., the upper décollement). A total of 49 models of tectonic inversion have been conducted varying (...
Conference Paper
Full-text available
The Central High Atlas in Morocco results from Cenozoic tectonic inversion of an inherited salt-related rift basin that developed during Late Triassic to Early Jurassic times, forming an intricate polygonal network of diapir walls separating minibasins (Moragas et al., 2017). In the present work, we conduct numerical models to test tectonic evoluti...
Article
Short- and long-term processes at or close to the subduction plate interface (e.g.,mineral transformations, fluid release, seismicity and more generally deformation) might be more closely related than previously thought. Increasing evidence from the fossil rock record suggests that some episodes of their long geological evolution match or are close...
Research
Full-text available
Gravitational collapse of a progradational delta leading to normal faulting along the proximal part and a fold-and-thrust belt in the distal part of the delta.
Article
Minibasins are sagging synformal depocenters surrounded by upsurging ductile material. They are traditionally related to salt tectonics. The onshore Iranian Makran accretionary wedge exhibits closed minibasins developed onto a regional-scale olistostrome with a shaly matrix. Two-dimensional numerical experiments were carried out to investigate whet...
Cover Page
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Conference Paper
Full-text available
In collisional foredeeps, rifted continental margins become buried by foreland sedimentary deposits and, ultimately , are overridden by advancing fold-and-thrust belts. With ongoing collision, stresses are transmitted into the foreland plate, causing positive inversion of buried rift basins in the sub-thrust region; ultimately, rift basins may beco...
Conference Paper
Typical fanning of beds in the different formations of the Fars Group and the unconformities between them in the Dehdasht Structural Basin in the Dezful Embayment could be either related to shortening or diapirism or both. The thick Miocene Gachsaran evaporites at the base of Miocene-Pleistocene syn-tectonic siliciclastic deposits of the Fars Group...
Article
The structural evolution of basement-involved, or thick-skinned, fold-and-thrust belts is often affected by preexisting, inherited extensional faults within the basement. Here, a crustal-scale two-dimensional finite difference model with a visco-elasto-brittle/plastic rheology is applied to investigate the formation of fold-and-thrust belts as a re...
Article
Numerical experiments on evolving accretionary wedges usually implement predefined weak basal décollements and constant strength parameters for overlying compressed sequences, although fluid pressure ratio, and therefore brittle strength, can vary strongly in sedimentary basins. A two-dimensional finite difference model with a visco-elasto-plasic r...
Conference Paper
Full-text available
In compressional systems, stress build-up in the continental crust is subject to horizontal forces. Upper differential stress thresholds in the Earth's crust are defined by the strength of brittle faults or ductile shear zones, depending of their rheological behavior. The longevity of such high strain rate zones is their mechanical weakness relativ...
Article
Defining the structural style of fold-and-thrust belts is an important step for understanding the factors that control their long- and short-term dynamics, for comprehending seismic hazard associated with them, and for assessing their economic potential. While the thin-skinned model (no basement involvement) has long been the driving methodology fo...
Article
Full-text available
Seamounts or submarine volcanoes frequently collide with the overriding crust along presently active subduction zones locally modifying stress and permanent deformation patterns. Dynamics of this process is not fully understood and several end-member scenarios of seamount-crust interaction are proposed. Here, we use high-resolution 3D numerical mod...
Article
A multidisciplinary provenance study, including sandstone framework, heavy mineral analysis, in situ U-Pb dating of detrital zir-con, and Hf isotopic ratio analysis of dated zircons, was undertaken on Late Cretaceous– Miocene deep-marine turbiditic and deltaic sandstones of Makran accretionary wedge, SE Iran, to determine their sedimentary provenan...
Article
We present U-Pb zircon crystallization ages combined with major and trace element analyses, Sr-Nd isotopes and zircon in-situ Hf isotope analyses of intermediate to granitic intrusions along the southern segment of the N-S trending Sistan Suture Zone in eastern Iran. The Zahedan and Shah-Kuh Eocene plutons consist in a series of granite-granodiorit...
Article
Seamounts entering active subduction zone trenches initially collide with the frontal sedimentary accretionary wedges resulting in severe deformation of the overriding plate. A typical feature of this deformation is the occurrence of submarine landslides due to gravitational instabilities. Such landslides have been reported from the Middle America...
Article
Latest developments in computer power and computational solutions open new ways to envision complex natural systems. Advances in high-resolution 3D geodynamic modeling, in particular, allow investigating tectonic processes such as transpression, which involve “normal” and “tangential” kinematics with respect to the bulk orogenic trends. We demonstr...
Article
Multikilometer-sized slivers of high-pressure low-temperature metamorphic oceanic crust and mantle are observed in many mountain belts. These blueschist and eclogite units were detached from the descending plate during subduction. Large-scale thermo-mechanical numerical models based on finite difference marker-in-cell staggered grid technique are i...
Article
The temporal evolution of the Zagros Simply Folded Belt is constrained by a magnetostratigraphic sequence containing a progressive unconformity on the southern limb of the Kuh-e Ghol Ghol anticline, in the Central Fars. The investigated ~1400 m thick sequence exposes a regressive mega-cycle containing, from bottom to top, open and shallow marine ma...
Article
Shear zones are weaker than surrounding rocks. Whether weakening depends on accumulated strain or strain rate is debated. We used a three-dimensional numerical code with a visco-plastic/brittle rheology to investigate the influence of strain and strain-rate weakening (often referred to as velocity weakening) on the evolution of thin-skinned fold-an...
Article
mechanics and dynamics of thin-skinned compressible thrust wedges with prescribed offsets in the backstop, i.e., transfer zones, are investigated using a three-dimensional finite difference numerical model with a visco-brittle/plastic rheology. The main questions addressed are as follows: (i) What is the influence of the initial length of the backs...
Article
Full-text available
Thin-skinned fold-and-thrust belts related to convergence tectonics develop by scraping off a rock sequence along a weaker basal décollement often formed by water-saturated shale layers or low-viscosity salt horizons. A two-dimensional finite element model with a viscoelastoplastic rheology is used to investigate the structural evolution of fold-an...

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Projects

Projects (4)
Project
The project aims at gaining understanding of the structural evolution of rifted margins by combining interpretation of geophysical data sets, field analogs of rifted margins involved in fold-and-thrust belts and analog and numerical modeling. Combination of all these methodologies and the expertise of the members of the research group in several but related disciplines and areas will enable addressing some specific objectives to increase the knowledge of rifted margins but also the structural evolution of fold-and-thrust belts controlled by the inherited features of the involved rifted margins. These general thematic objectives will be the basis for a better knowledge of the subsurface structure of many sedimentary basins aiming to increase our capability for exploration and management of natural resources.
Project
The baseline assumption being made in this proposal is that heterogeneities (in the form of pre-exisiting faults, zones of sedimentary facies change etc.) in a continental margin that forms the underthrusting plate of a thrust-and-fold belt plays an important role in the development of transverse structures in the upper plate (the thrust-and-fold belt). The hypothesis to be tested is that pre-exisitng faults along the continental margin of southeast Eurasia are being reactivated forming transverse structures in the Taiwan thrust-and-fold belt. The corollary to this hypothesis is that there is a link between these transverse structures and re-activated basement faults during early stages of collision and this therefore affects not only the structure but also the seismicity and the landscape evolution. The main objective of this research is to use an integrated data set consisting of field geology, geophysical, geodetic, and potential field data to further the understanding of the importance of fault reactivation in the formation of transverse zones, to study how the linkage and displacement between these transverse zones and thrusts works, and what the effect is on transient features such as the stress field (calculated from earthquake focal mechanisms), seismicity, and topography. Taiwan is a particularly good place to investigate this process because it is possible to trace the main features of the margin (fault systems, margin morphology) into the undeformed and weakly deformed foreland and, we think, farther into the thrust-and-fold belt itself. Furthermore, the whole (pre-existing fault systems entering the deformation, faults forming the thrust-and-fold belt, and the sedimentary system of the foreland basin) is active, meaning that the transverse structures can be illuminated at depth by earthquakes and, therefore, high-resolution seismic tomography. Taiwan, then, provides an exceptional setting for the study of the causal relationships between the formation of transverse structures in a thrust-and-fold belt and a margin’s morphology and heterogeneities.
Project
Tectono-sedimentary evolution of the Dehdasht Structural Basin using growth strata, seismic interpretation and numerical modeling