Folding and imbrication of the Indian crust during Himalayan collision

1988 ◽  
Vol 326 (1589) ◽  
pp. 89-116 ◽  
Keyword(s):  
Local Development ◽  
Sedimentary Cover ◽  
Three Dimensional ◽  
Indian Plate ◽  
Small Scale ◽  
Plate Convergence ◽  
The North ◽  
Basement Rocks ◽  
Wide Range ◽  
Minimum Displacement

India collided with a northern Kohistan-Asian Plate at about 50 Ma ago, the time of ocean closure being fairly accurately defined from syntectonic sediments as well as the effect on magnetic stripes on the Indian Ocean floor. Since collision, Asia has over-ridden India, developing a wide range of thrust scrapings at the top of the Indian Plate. Sections through the imbricated sedimentary cover suggest a minimum displacement of over 500 km during Eocene to recent plate convergence. This requires the Kohistan region to the north to be underlain by underthrusted middle to lower Indian crust, deformed by ductile shears and recumbent folds. These structures are well seen in the gneisses immediately south of the suture, where they are uplifted in the Indus and Nanga Parbat syntaxes. Here there are several phases of thrust-related small-scale folding and the development of a large folded thrust stack involving basement rocks, the imbrication of metamorphic zones and the local development of large backfolds. Some of the important local structures: the large late backfolds, the Salt Ranges and the Peshawar Basin, can all be related to the necessary changes in thrust wedge shape as it climbs through the crust and the three dimensional nature of the thrust movements associated with interference between the Kohistan and western Himalayan trends.

Using basement-hosted clastic dykes as syn-rifting palaeostress indicators: an example from the basal Stoer Group, northwest Scotland

1999 ◽  
Vol 136 (3) ◽  
pp. 301-310 ◽  
Author(s):  
L. E. BEACOM ◽  
T. B. ANDERSON ◽  
R. E. HOLDSWORTH
Keyword(s):  
Sedimentary Cover ◽  
Regional Scale ◽  
Three Dimensional ◽  
Tensile Fracture ◽  
Stress Inversion ◽  
The North ◽  
Basement Rocks ◽  
Basement Faults ◽  
Half Graben ◽  
Inversion Techniques

Clastic infills of fractures (here termed clastic veins) in basement rocks immediately underlying sedimentary cover sequences can be used to date fault movements if these demonstrably occurred at the time of infilling or prior to the lithification of the entrained clastic material. This allows reconstruction of the syn-rifting palaeostress system using stress inversion techniques. During Riphean intracontinential rifting of Laurentia, the Torridonian Stoer Group sediments of northwest Scotland were deposited in half-graben basins controlled by faults, e.g. the Coigach and Clachtoll faults. At Clachtoll, northeast–southwest oblique sinistral normal faulting in the underlying basement is associated with extensive development of shear, hybrid and tensile clastic veins filled with Stoer Group sediment, infilled and deformed prior to sediment lithification. Clastic veins initially formed by gravitational infilling of sediment from above, followed by tectonically-driven, forceful hydraulic injection of fluidized sand into new fractures and reactivated pre-existing basement faults. Palaeostress axes, determined from fault lineation data and tensile fracture extension directions in the Clachtoll Fault zone, indicate west-northwest–east-southeast directed extension during rifting. On a regional scale, this implies oblique-dextral extension on the north- to north-northeast-trending Coigach Fault during Stoer Group deposition. Similar orientations, age relationships and kinematics have been obtained from pre-Torridon Group fault arrays developed in the Lewisian basement near Gairloch and Loch Maree. Overall, the faulting patterns reflect a three-dimensional strain (k≠1) formed by east-southeast–west-northwest-directed extension during deposition of the Stoer Group. More speculatitively, asymmetric density patterns of sinistral and dextral faults may indicate that rifting occurred in a regional zone of broadly north–south-oriented dextral transtension.

Editorial

2021 ◽  
Vol 23 (1) ◽  
pp. 1-4
Author(s):  
Eva Cendon ◽  
John Butcher
Keyword(s):  
Further Education ◽  
University Education ◽  
Small Scale ◽  
Widening Participation ◽  
The North ◽  
Research Activities ◽  
International Perspectives ◽  
Wide Range ◽  
International Sector ◽  
The Uk

This general edition of the journal provides insights and results of research employing a wide range of approaches and perspectives on widening participation and lifelong learning. Studies from across the UK and international sector utilise different methodological approaches, and as such are particularly interesting, with diverse methods and ways of analysis, including phenomenographic, narrative, and thematic analysis. Overall, the articles range from exploratory case studies and small-scale research to wider range and broad scale studies, highlighting different facets and perspectives. Furthermore, the articles in this volume cover a broad spectrum of institutions and places involved in widening participation, with an emphasis on the (higher) education sector in the UK balanced by international perspectives. The first seven empirical articles are based on research activities in a secondary school, a youth centre, in further education colleges (usually focusing on post-compulsory secondary or pre-university education), in so-called post-92 universities (new(er) universities, formerly Polytechnics and teacher training colleges), and last but not least in a research intensive Russell Group university. They reported challenges from the specific local contexts of different regions in England, from the South (Chichester) to London to the North (Carlisle), and can usefully be framed in the context of international discussions appearing later in the journal.

scholarly journals Dynamics of Orographically Triggered Banded Convection in Sheared Moist Orographic Flows

2007 ◽  
Vol 64 (10) ◽  
pp. 3542-3561 ◽  
Author(s):  
Oliver Fuhrer ◽  
Christoph Schär
Keyword(s):  
Small Amplitude ◽  
Three Dimensional ◽  
Horizontal Resolution ◽  
Small Scale ◽  
Mean Flow ◽  
Topographic Roughness ◽  
Wide Range ◽  
Orographic Convection ◽  
Wind Profiles

Abstract Shallow orographic convection embedded in an unstable cap cloud can organize into convective bands. Previous research has highlighted the important role of small-amplitude topographic variations in triggering and organizing banded convection. Here, the underlying dynamical mechanisms are systematically investigated by conducting three-dimensional simulations of moist flows past a two-dimensional mountain ridge using a cloud-resolving numerical model. Most simulations address a sheared environment to account for the observed wind profiles. Results confirm that small-amplitude topographic variations can enhance the development of embedded convection and anchor quasi-stationary convective bands to a fixed location in space. The resulting precipitation patterns exhibit tremendous spatial variability, since regions receiving heavy rainfall can be only kilometers away from regions receiving little or no rain. In addition, the presence of banded convection has important repercussions on the area-mean precipitation amounts. For the experimental setup here, the gravity wave response to small-amplitude topographic variations close to the upstream edge of the cap cloud (which is forced by the larger-scale topography) is found to be the dominant triggering mechanism. Small-scale variations in the underlying topography are found to force the location and spacing of convective bands over a wide range of scales. Further, a self-sufficient mode of unsteady banded convection is investigated that does not dependent on external perturbations and is able to propagate against the mean flow. Finally, the sensitivity of model simulations of banded convection with respect to horizontal computational resolution is investigated. Consistent with predictions from a linear stability analysis, convective bands of increasingly smaller scales are favored as the horizontal resolution is increased. However, small-amplitude topographic roughness is found to trigger banded convection and to control the spacing and location of the resulting bands. Thereby, the robustness of numerical simulations with respect to an increase in horizontal resolution is increased in the presence of topographic variations.

scholarly journals Measurement of three-dimensional displacement field in piled embankments using synchrotron X-ray tomography

2019 ◽  
Vol 56 (6) ◽  
pp. 885-892 ◽  
Author(s):  
Louis King ◽  
Abdelmalek Bouazza ◽  
Anton Maksimenko ◽  
Will P. Gates ◽  
Stephen Dubsky
Keyword(s):  
High Resolution ◽  
Imaging Techniques ◽  
Three Dimensional ◽  
Physical Models ◽  
Scale Model ◽  
Small Scale ◽  
Full Field ◽  
X Ray ◽  
Wide Range ◽  
Piled Embankments

The measurement of displacement fields by nondestructive imaging techniques opens up the potential to study the pre-failure mechanisms of a wide range of geotechnical problems within physical models. With the advancement of imaging technologies, it has become possible to achieve high-resolution three-dimensional computed tomography volumes of relatively large samples, which may have previously resulted in excessively long scan times or significant imaging artefacts. Imaging of small-scale model piled embankments (142 mm diameter) comprising sand was undertaken using the imaging and medical beamline at the Australian Synchrotron. The monochromatic X-ray beam produced high-resolution reconstructed volumes with a fine texture due to the size and mineralogy of the sand grains as well as the phase contrast enhancement achieved by the monochromatic X-ray beam. The reconstructed volumes were well suited to the application of digital volume correlation, which utilizes cross-correlation techniques to estimate three-dimensional full-field displacement vectors. The output provides insight into the strain localizations that develop within piled embankments and an example of how advanced imaging techniques can be utilized to study the kinematics of physical models.

scholarly journals Analysis of Three-Dimensional Space Expansion Characteristics in Old Industrial Area Renewal Using GIS and Barista: A Case Study of Tiexi District, Shenyang, China

2019 ◽  
Vol 11 (7) ◽  
pp. 1860 ◽  
Author(s):  
Yanyan Xu ◽  
Miao Liu ◽  
Yuanman Hu ◽  
Chunlin Li ◽  
Zaiping Xiong
Keyword(s):  
Dimensional Space ◽  
Urban Expansion ◽  
Three Dimensional ◽  
Industrial Area ◽  
Urban Morphology ◽  
Average Height ◽  
Landscape Index ◽  
The North ◽  
Gis Tools ◽  
Wide Range

With rapid urban development in China in the last two decades, 3D characteristics have been the main feature of urban morphology. Nevertheless, the vast majority of urban growth research has only focused on area expansion horizontally, with few studies conducted in a 3D perspective. In this paper, the characteristics of 3D expansion that occurred in Tiexi from 1997 to 2011 were evaluated based on geographic information system (GIS) tools, remote-sensing images, and Barista software. Landscape index, the spatiotemporal distribution of changes in buildings’ renewal modes and variations in city skylines as well as the relationship between number and size of high-rise buildings are the specific phenomena and data utilized to quantify the 3D urban expansion. The results showed that the average height of Tiexi increased by 0.69 m annually, the average urban capacity increased by 490.15 m3 annually, and space congestion degree increased by 0.11% annually. The average annual increase of the building evenness index was 36.43. The renewal area occupied up to 75.38% of the total area. The change of the skyline was more consistent with the east–west direction. The change in the south direction was significant, while in the north direction it was relatively slow. The overall shape of the city was that of a weak pyramid, with the angle of the top of the pyramid gradually becoming larger. The methods proposed in this paper laid a foundation for a wide range of study of 3D urban morphology changes.

scholarly journals Finescale Structure of the T–S Relation in the Eastern North Atlantic

2005 ◽  
Vol 35 (8) ◽  
pp. 1437-1454 ◽  
Author(s):  
R. Ferrari ◽  
K. L. Polzin
Keyword(s):  
North Atlantic ◽  
Large Scale ◽  
Salinity Gradient ◽  
Mesoscale Eddies ◽  
Thermal Dissipation ◽  
Small Scale ◽  
The North ◽  
Wide Range ◽  
Using Data ◽  
Gyre Circulation

Abstract Distributions of temperature (T) and salinity (S) and their relationship in the oceans are the result of a balance between T–S variability generated at the surface by air–sea fluxes and its removal by molecular dissipation. In this paper the role of different motions in setting the cascade of T–S variance to dissipation scales is quantified using data from the North Atlantic Tracer Release Experiment (NATRE). The NATRE observational programs include fine- and microscale measurements and provide a snapshot of T–S variability across a wide range of scales from basin to molecular. It is found that microscale turbulence controls the rate of thermal dissipation in the thermocline. At this level the T–S relation is established through a balance between large-scale advection by the gyre circulation and small-scale turbulence. Further down, at the level of intermediate and Mediterranean waters, mesoscale eddies are the rate-controlling process. The transition between the two regimes is related to the presence of a strong salinity gradient along density surfaces associated with the outflow of Mediterranean waters. Mesoscale eddies stir this gradient and produce a rich filamentation and salinity-compensated temperature inversions: isopycnal stirring and diapycnal mixing are both required to explain the T–S relation at depth.

scholarly journals A multiscale ocean data assimilation approach combining spatial and spectral localisation

Ocean Science ◽  
2019 ◽  
Vol 15 (2) ◽  
pp. 443-457 ◽  
Author(s):  
Ann-Sophie Tissier ◽  
Jean-Michel Brankart ◽  
Charles-Emmanuel Testut ◽  
Giovanni Ruggiero ◽  
Emmanuel Cosme ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Large Scale ◽  
Spectral Domain ◽  
Small Scale ◽  
Error Statistics ◽  
The North ◽  
Ocean Data Assimilation ◽  
Wide Range ◽  
Spatial Localisation ◽  
Operational Systems

Abstract. Ocean data assimilation systems encompass a wide range of scales that are difficult to control simultaneously using partial observation networks. All scales are not observable by all observation systems, which is not easily taken into account in current ocean operational systems. The main reason for this difficulty is that the error covariance matrices are usually assumed to be local (e.g. using a localisation algorithm in ensemble data assimilation systems), so that the large-scale patterns are removed from the error statistics. To better exploit the observational information available for all scales in the assimilation systems of the Copernicus Marine Environment Monitoring Service, we investigate a new method to introduce scale separation in the assimilation scheme. The method is based on a spectral transformation of the assimilation problem and consists in carrying out the analysis with spectral localisation for the large scales and spatial localisation for the residual scales. The target is to improve the observational update of the large-scale components of the signal by an explicit observational constraint applied directly on the large scales and to restrict the use of spatial localisation to the small-scale components of the signal. To evaluate our method, twin experiments are carried out with synthetic altimetry observations (simulating the Jason tracks), assimilated in a 1/4∘ model configuration of the North Atlantic and the Nordic Seas. Results show that the transformation to the spectral domain and the spectral localisation provides consistent ensemble estimates of the state of the system (in the spectral domain or after backward transformation to the spatial domain). Combined with spatial localisation for the residual scales, the new scheme is able to provide a reliable ensemble update for all scales, with improved accuracy for the large scale; and the performance of the system can be checked explicitly and separately for all scales in the assimilation system.

scholarly journals Self-organization in a driven dissipative plasma system

2009 ◽  
Vol 76 (1) ◽  
pp. 107-116 ◽  
Author(s):  
DASTGEER SHAIKH ◽  
B. DASGUPTA ◽  
Q. HU ◽  
G. P. ZANK
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Spectral Energy ◽  
Small Scale ◽  
Plasma System ◽  
Self Organized ◽  
Wide Range ◽  
Characteristic Modes ◽  
Perpendicular Component ◽  
Migration Of Energy

AbstractWe perform a fully self-consistent three-dimensional numerical simulation for a compressible, dissipative magnetoplasma driven by large-scale perturbations, that contain a fairly broad spectrum of characteristic modes, ranging from largest scales to intermediate scales and down to the smallest scales, where the energy of the system is dissipated by collisional (ohmic) and viscous dissipations. Additionally, our simulation includes nonlinear interactions amongst a wide range of fluctuations that are initialized with random spectral amplitudes, leading to the cascade of spectral energy in the inertial range spectrum, and takes into account large-scale as well as small-scale perturbations that may have been induced by the background plasma fluctuations, as well as the non-adiabatic exchange of energy leading to the migration of energy from the energy-containing modes or randomly injected energy driven by perturbations and further dissipated by the smaller scales. Besides demonstrating the comparative decays of the total energy and the dissipation rate of the energy, our results show the existence of a perpendicular component of the current, thus clearly confirming that the self-organized state is non-force free.

scholarly journals DEVELOPING MARKETING STRATEGIES FOR FOOD DIVERSITY: A CASE-STUDY IN NORTHERN PORTUGAL

2018 ◽  
Author(s):  
Isabel Dinis ◽  
Pedro Mendes-Moreira ◽  
Susanne Padel
Keyword(s):  
Value Chain ◽  
Local Development ◽  
Genetic Erosion ◽  
Small Scale ◽  
Study Approach ◽  
The North ◽  
Processing Level ◽  
Maize Varieties ◽  
Local Actors

Vale do Sousa is a heterogeneous territory located in the North Region of Portugal. Until a few decades ago, the economy was based on small-scale farming with maize for bread (Broa) as one important crop. Each community had its own maize varieties and practices, which were reflected in the composition, shape, size and flavour of local Broa. In the last decades, the abandonment of agriculture was noticeable, leading to a progressive decrease in maize production and to genetic erosion. More recently, local stakeholders became aware of the important role that landraces and biodiverse food can play in local development and have engaged in finding new opportunities for a sustainable Broa value chain development in Vale do Sousa region. This paper aims at identifying opportunities and bottlenecks in the marketing of regional Broa. It uses a case study approach that, unlike the majority of the research in this area, covers the whole supply chain and includes needs and expectations of farmers, processors, consumers and their networks. The main problem identified by local actors is that traditional varieties are less productive, leading farmers to favour commercial maize varieties less suitable for baking. At the processing level, local actors raised the question of legislation, arguing that, in Portugal, European rules on food safety are not realistically applied to endogenous food products. The results also show that final consumers as well as restaurants recognize the quality of traditional Broa and seem to be willing to pay a price premium to reward farmers for using traditional varieties.

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