scholarly journals Role of rift-inheritance and segmentation for orogenic evolution: example from the Pyrenean-Cantabrian system

2020 ◽  
Vol 191 ◽  
pp. 18 ◽  
Author(s):  
Rodolphe Lescoutre ◽  
Gianreto Manatschal
Keyword(s):  
Cross Sections ◽  
Seismic Data ◽  
Large Scale ◽  
Sedimentary Cover ◽  
First Order ◽  
Segment Boundary ◽  
Orogenic Wedge ◽  
Mountain Belts ◽  
Two Phases

The Basque-Cantabrian junction corresponds to an inverted rift accommodation zone at the limit between the former hyperextended Pyrenean and Cantabrian rift segments. The recognition of an inherited rift segment boundary allows to investigate the reactivation associated with large-scale rift segmentation in an orogenic system. We use criteria from published field observations and seismic data to propose a new map of rift domains for the Basque-Cantabrian junction. We also provide balanced cross-sections that allow to define the along-strike architecture associated with segmentation during rifting and subsequent Alpine reactivation. Based on these results, this study aims to characterize and identify reactivated and newly formed structures during inversion of two rift segments and its intermitted segment boundary. It also aims to describe the timing of thin-skinned and thick-skinned deformation associated with the inversion of segmented rift systems. During convergence, two phases have been recognized within the rift segment (eastern Mauléon basin). The Late Cretaceous to Paleocene underthrusting/subduction phase was mostly governed by thin-skinned deformation that reactivated the former hyperextended domains and the supra-salt sedimentary cover. The Eocene to Miocene collisional phase, controlled by thick-skinned deformation that took place once necking domains collided and formed an orogenic wedge. At the rift segment boundary, the underthrusting/subduction phase was already controlled by thick-skinned deformation due to the formation of shortcutting thrust faults at the termination of overlapping V-shaped rift segments. This led to the formation of a proto-wedge composed of the Basque massifs. We suggest that this proto-wedge is responsible for the preservation of pre-Alpine structures in the Basque massifs and for the emplacement of subcontinental mantle rocks at a crustal level beneath the western Mauléon basin. These results argue for a first order cylindrical orogenic architecture from the Central Pyrenean segment to the Cantabrian segment (up to the Santander transfer zone) despite rift segmentation. They also highlight the control of 3D rift-inheritance for the initial phase of orogenic evolution and for the local architecture of mountain belts.

Rift evolution and structural style in the Orphan Basin: results from regional structural restorations and crustal area balancing 

2021 ◽  
Author(s):  
Adam J. Cawood ◽  
David A. Ferrill ◽  
Alan P. Morris ◽  
David Norris ◽  
David McCallum ◽  
...  
Keyword(s):  
Cross Sections ◽  
Seismic Data ◽  
Large Scale ◽  
Structural Evolution ◽  
Strike Slip ◽  
Detachment Faults ◽  
The North ◽  
Structural Style ◽  
Complex Structural ◽  
Structural Configurations

<p>The Orphan Basin on the eastern edge of the Newfoundland continental margin formed as a Mesozoic rift basin prior to continental breakup associated with the opening of the North Atlantic. Few exploration wells exist in the basin, and until recently regional interpretations have been based on sparse seismic data coverage - because of this the structural evolution of the Orphan Basin has historically not been well understood. Key uncertainties include the timing and amount of rift-related extension, dominant extension directions, and the structural styles that accommodated progressive rift development in the basin.     </p><p>Interpretation of newly acquired modern broadband seismic data and structural restoration of three regional, WNW-ESE oriented cross-sections across the Orphan Basin and Flemish Cap provide new insights into rift evolution and structural style in the area. Our results show that major extension in the basin occurred between 167 Ma and 135 Ma, with most extension occurring prior to 151 Ma. We show that extension after 135 Ma largely occurred east of Flemish Cap due to a shift in the locus of rifting from the Orphan Basin to east of Flemish Cap. We find no evidence for discrete rifting events in the Orphan Basin, as has been suggested by other authors.  Kinematic restoration and associated heave measurements for the Orphan Basin show that extension was both widespread and relatively evenly distributed across the basin from Middle-Late Jurassic to Early Cretaceous.</p><p>We provide evidence for more widespread deposition of Jurassic strata throughout the Orphan Basin than previously interpreted, and show that Jurassic deposition was controlled by the occurrence and displacement of crustal-scale extensional detachment faults.  Structure in the three regional cross sections is dominated by large-scale, shallowly dipping extensional detachment faults. These faults mainly dip to the northwest and control the geometry and position of extensional basins – grabens and half-grabens – which occur at a range of scales. Stacked detachment surfaces, hyperextension, and attenuation of the crust are observed in central and eastern parts of the Orphan Basin. Zones of extreme crustal attenuation (to ca. 3.7 km) are interpreted to be coincident with large-displacement (up to 60 km) low-angle detachments. Results from crustal area balancing suggest that up to 41% of extension is not recognized through structural seismic interpretation, which we attribute to subseismic-scale ductile and brittle deformation, and uncertainties in the identification of detachment surfaces or complex structural configurations (e.g., overprinting of early extensional deformation).</p><p>Rifting style in the central, northern, and eastern parts of the Orphan Basin is dominated by low-angle detachment faulting with maximum extension perpendicular to the incipient rift axis. In contrast, structural geometries in the southwestern part of the basin are suggestive of transtensional deformation, and interplay of normal and strike-slip faulting.  Results from map-based interpretation show that strike-slip faults within this transtensional zone are associated with displacement transfer between half-grabens of opposing polarity, rather than regional strike-slip displacement.  These structures are interpreted as contemporaneous and kinematically linked to displacement along low-angle detachment surfaces elsewhere, and are not attributed to distinct episodes of oblique extension.       </p>

The Role of Inclusions in the Corrosion Resistance of Hydrostatically Extruded Steel Products

2006 ◽  
Vol 114 ◽  
pp. 189-198 ◽  
Author(s):  
Dominika Klassek ◽  
Thomas Suter ◽  
Patrik Schmutz ◽  
Wacław Pachla ◽  
Małgorzata Lewandowska ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Cross Sections ◽  
Small Area ◽  
Large Scale ◽  
Corrosion Behaviour ◽  
Nacl Solution ◽  
Polarization Measurements

The corrosion behaviour of 316LVM in NaCl solution steel has been investigated. Large scale polarization measurements and etching tests in V2A solution showed that the hydrostatically extruded (HE) 316LVM steel had a lower corrosion resistance than specimens in the as received condition. Small area measurements were carried out in order to determine the sites that were responsible for the decreased corrosion resistance of the HE 316LVM steel. Tests on cross sections parallel to the HE direction, showed better corrosion resistance than on cross sections perpendicular to the HE direction. These observations indicate, in combination with SEM and AFM measurements, that the inclusions which were deformed during HE, can trigger the onset of corrosion on HE 316LVM steel.

Extension and early orogenic inversion along the basal detachment of a hyper-extended rifted margin: an example from the Central Pyrenees (France)

2021 ◽  
pp. jgs2020-003
Author(s):  
Paul Angrand ◽  
Mary Ford ◽  
Maxime Ducoux ◽  
Michel De Saint Blanquat
Keyword(s):  
Cross Sections ◽  
Sedimentary Cover ◽  
Low Grade ◽  
Content Type ◽  
The North ◽  
Metamorphic Zone ◽  
Supplementary Material ◽  
Tectonic Loading ◽  
Rifted Margin

The North Pyrenean Zone (NPZ) inverts remnants of an Aptian-Cenomanian rifting during which subcontinental mantle was exhumed. These remnants contain a syn-rift HT-LP metamorphic domain, the Internal Metamorphic Zone (IMZ). New field and RSCM data and structural cross-sections constrain the structural and metamorphic relationships between the IMZ and the underlying low-grade NPZ. The IMZ is a tectonic nappe that overthrusts the European margin along the 3M Fault. Along this contact, the Tuc de Haurades peridotite is surrounded by tectonic breccia composed of ductilely deformed carbonate and sparse lherzolite clasts that passes upward into foliated marbles. Marbles contain top-to-south ductile shear, recording ongoing extensional deformation that marks the onset of HT metamorphism. During Early Cretaceous rifting, European Mesozoic sedimentary cover metamorphosed and its base brecciated as it slid basinward on Triassic salt onto exhumed mantle. As the exhumed mantle domain closed during early convergence, the detached metamorphosed cover was transported northward and thrust into the distal European margin, sampling lherzolite tectonic lenses. This triggered the first tectonic loading on the European plate. This study highlights the role of the IMZ in the early Pyrenean orogenic phase and gives new insights on the E-W diversity of structural setting of the NPZ peridotites.Table with RSCM temperatures and original and high quality photographs of the samples are available on the GSL Figshare portal https://doi.org/10.6084/m9.figshare.c.5539260.

Onset of Carnegie Ridge subduction from low-temperature thermochronology

2021 ◽  
Author(s):  
Audrey Margirier ◽  
Manfred Strecker ◽  
Peter Reiners ◽  
Ismael Casado ◽  
Stuart Thomson ◽  
...  
Keyword(s):  
Cross Sections ◽  
Tectonic Activity ◽  
Ridge Subduction ◽  
The Andes ◽  
Western Cordillera ◽  
Deformation Processes ◽  
Age Patterns ◽  
Cooling Phase ◽  
Two Phases

<p>Cenozoic growth of the Andes has been strongly influenced by subduction dynamics, inherited crustal heterogeneities, and the superposed effects of climate. Subduction of the Carnegie Ridge in Ecuador has impacted late Cenozoic magmatism and tectonic activity, including the formation of a crustal sliver escaping northward. However, the relationship between ridge subduction and topographic growth has remained unclear. We present new thermochronological data from the Western Cordillera of Ecuador to (1) pinpoint the timing of ridge subduction, and (2) evaluate the role of ridge subduction in prompting growth of the Ecuadorian Andes. Time-temperature inverse modeling of our results shows two phases of cooling separated by tectonic quiescence. The first cooling phase immediately post-dates magmatism in the Western Cordillera, and hence we attribute it to magmatic cooling. The second cooling phase starts at ~6-5 Ma. This we associate with onset of enhanced exhumation at this time in the Western Cordillera, synchronous with the last cooling phase in the Eastern Cordillera. Based on our thermal modeling and thermochronological age patterns along geological cross-sections we propose that recent crustal shortening and rock uplift triggered exhumation of Western Ecuadorian Andes starting at ~6-5 Ma. We suggest that the onset of Carnegie Ridge subduction in the latest Miocene increased the coupling at the subduction interface and promoted shortening and regional rock uplift in the northern Andes. Overall, our new thermochronological results highlight the pivotal role of bathymetric anomalies in distinct upper-plate deformation processes at non-collisional convergent plate margins.</p>

scholarly journals ArtsEqual 2015–2021: The challenges of a Large-Scale Research Initiative in Finland

2018 ◽  
Vol 5 (1) ◽  
pp. 1-11
Author(s):  
Sari Karttunen ◽  
Pia Houni
Keyword(s):  
Large Scale ◽  
System Analysis ◽  
Research Teams ◽  
Strategic Research ◽  
The Arts ◽  
Research Initiative ◽  
Two Phases ◽  
In The Beginning ◽  
Changing Role

The article presents the ArtsEqual initiative, which is funded by the strategic research council of the Academy of Finland. The six-year project, funded from a sub-programme aiming to increase equality in society, is constructed on the visionary question: What if the arts were understood to be an essential part of public services? The project sets out to identify mechanisms and remove barriers that hinder equality from being established both within the arts and through them in society at large. The project is multidisciplinary and draws largely upon participatory, practice-led methodologies. It is carried out in six research teams and in two phases, the first of which consisted of numerous arts interventions combined with research. The conclusive phase that links the findings and experiences from the case studies together via qualitative system analysis started in the beginning of 2018. The authors are leaders of two of the research teams, and here they present the entire research initiative as well as exemplary sub-studies from their own teams. They discuss the research project and the preliminary findings in view of the changing role of the artist in society, a shared problematic between their teams. They also reflect on the advantages and challenges that programmatic funding may bring to artistic practices and research.

scholarly journals Frequency patterns of semantic change: corpus-based evidence of a near-critical dynamics in language change

2017 ◽  
Vol 4 (11) ◽  
pp. 170830 ◽  
Author(s):  
Q. Feltgen ◽  
B. Fagard ◽  
J.-P. Nadal
Keyword(s):  
Large Scale ◽  
Language Change ◽  
Driving Mechanism ◽  
Semantic Change ◽  
Linguistic Item ◽  
Frequency Of Use ◽  
S Curve ◽  
Two Phases ◽  
Passage Times

It is generally believed that when a linguistic item acquires a new meaning, its overall frequency of use rises with time with an S-shaped growth curve. Yet, this claim has only been supported by a limited number of case studies. In this paper, we provide the first corpus-based large-scale confirmation of the S-curve in language change. Moreover, we uncover another generic pattern, a latency phase preceding the S-growth, during which the frequency remains close to constant. We propose a usage-based model which predicts both phases, the latency and the S-growth. The driving mechanism is a random walk in the space of frequency of use. The underlying deterministic dynamics highlights the role of a control parameter which tunes the system at the vicinity of a saddle-node bifurcation. In the neighbourhood of the critical point, the latency phase corresponds to the diffusion time over the critical region, and the S-growth to the fast convergence that follows. The durations of the two phases are computed as specific first-passage times, leading to distributions that fit well the ones extracted from our dataset. We argue that our results are not specific to the studied corpus, but apply to semantic change in general.

scholarly journals Surface processes versus kinematics of thrust belts: impact on rates of erosion, sedimentation, and exhumation – Insights from analogue models

2008 ◽  
Vol 179 (3) ◽  
pp. 297-314 ◽  
Author(s):  
Cécile Bonnet ◽  
Jacques Malavieille ◽  
Jon Mosar
Keyword(s):  
Cross Sections ◽  
Foreland Basin ◽  
Surface Processes ◽  
Molasse Basin ◽  
Structural Units ◽  
Tectonic Processes ◽  
Thrust Belts ◽  
Orogenic Wedge ◽  
Analogue Models

Abstract The mechanical equilibrium of an orogenic wedge is maintained thanks to interactions between tectonic processes and surface processes. To better constrain the influence of erosion and sedimentation on the evolution of orogens, we performed a series of analogue models based on the tapered wedge principle, varying the amounts of erosion and sedimentation. The models develop by frontal accretion in the foreland basin and by simple underthrusting and subsequent underplating in the hinterland. The variations in rates of erosion and sedimentation strongly modify the extent, the morphology, the structures, the timing of development and the material paths in the different models. Under certain conditions, entire structural units can be formed and subsequently eroded out of the geological record, leading to important underestimations when restoring sections. Particles located in the converging lower-plate or in the upper-plate show complex uplift paths related to tectonic stages. The correlation between models and three Alpine tectonic cross-sections emphasizes the role of erosion and sedimentation on the dynamics and development of the orogen and adjacent Molasse basin. Along strike changes in the present structure of the orogen could be explained in part by differences in surface processes.

scholarly journals An analytical solution for the exhumation of an orogenic wedge and a comparison with thermochronology data

2021 ◽  
Author(s):  
Elco Luijendijk ◽  
Leo Benard ◽  
Sarah Louis ◽  
Christoph von Hagke ◽  
Jonas Kley
Keyword(s):  
Steady State ◽  
Analytical Solution ◽  
Large Scale ◽  
Coefficient Of Determination ◽  
Uniform Compression ◽  
Orogenic Wedge ◽  
Rate Of Increase ◽  
Internal Deformation ◽  
Mountain Belts ◽  
Basal Detachment

Abstract. Thermochronology data is key for quantifying the exhumation history and dynamics of mountain belts. Here we present a new analytical solution for the steady-state exhumation of an orogenic wedge that undergoes transport along a basal detachment, uniform internal deformation, basal and frontal accretion. The solution predicts an increase in exhumation towards the interior of the wedge, with the rate of increase dependent on the degree of internal deformation. Application of the solution to a cross section in the Himalayas shows that in spite of its simplicity the solution provides a good fit to thermochronology data, with a coefficient of determination (R2) of 0.75. This implies that, although the solution does not capture the effects of individual faults and folds, at a large scale deformation can be described by uniform compression and transport. The results also imply that this part of the Himalayas may be in steady-state. The equations presented here can be used to quantify exhumation, deformation and shortening rates in mature orogens that are in steady-state.

Oxygen K near edge structures studied with multiple scattering calculations

1988 ◽  
Vol 46 ◽  
pp. 504-505
Author(s):  
Xudong Weng ◽  
Peter Rez
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Partial Cross Section ◽  
Energy Window ◽  
Edge Structure ◽  
Fine Structures ◽  
Hydrogenic Model ◽  
Electron Energy Loss ◽  
Quantitative Chemical

In electron energy loss spectroscopy, quantitative chemical microanalysis is performed by comparison of the intensity under a specific inner shell edge with the corresponding partial cross section. There are two commonly used models for calculations of atomic partial cross sections, the hydrogenic model and the Hartree-Slater model. Partial cross sections could also be measured from standards of known compositions. These partial cross sections are complicated by variations in the edge shapes, such as the near edge structure (ELNES) and extended fine structures (ELEXFS). The role of these solid state effects in the partial cross sections, and the transferability of the partial cross sections from material to material, has yet to be fully explored. In this work, we consider the oxygen K edge in several oxides as oxygen is present in many materials. Since the energy window of interest is in the range of 20-100 eV, we limit ourselves to the near edge structures.

The Role of Sense of Direction and Other Factors During Navigation in a Large-Scale, Unconstrained Environment

2013 ◽  
Author(s):  
Elisabeth J. Ploran ◽  
Ericka Rovira ◽  
James C. Thompson ◽  
Raja Parasuraman
Keyword(s):  
Large Scale ◽  
Sense Of Direction
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