scholarly journals Pinch and swell structures: evidence for strain localisation by brittle–viscous behaviour in the middle crust

Solid Earth ◽  
2015 ◽  
Vol 6 (3) ◽  
pp. 1045-1061 ◽  
Author(s):  
R. L. Gardner ◽  
S. Piazolo ◽  
N. R. Daczko
Keyword(s):  
Viscous Flow ◽  
Country Rock ◽  
Shear Bands ◽  
Rheological Behaviour ◽  
Scale Model ◽  
Flow Properties ◽  
Strain Localisation ◽  
Near Surface ◽  
Middle Crust ◽  
Alternative Representation

Abstract. The flow properties of middle crustal rocks are commonly represented by viscous flow. Examples of pinch and swell structures found in a high strain zone at St. Anne Point (Fiordland, New Zealand) and Wongwibinda (N.S.W., Australia) suggest pinch and swell structures may be initiated by brittle failure of the more competent layer in conjunction with subsequent material softening. On this basis we develop a numerical model where Mohr–Coulomb constitutive strain localising behaviour is utilised to initiate pinch and swell structure development. Results show that pinch and swell structures develop in a competent layer in both Newtonian and non-Newtonian flow, provided the competent layer has sufficient viscosity contrast and can localise strain to form shear bands. The flow regime and strain localising characteristics of the surrounding country rock appear not to impact pinch and swell structure formation. The degree of material softening after the initial strain localising behaviour is shown to impact pinch and swell characteristics, while extensive material softening causes the formation of thick necks between swells by limiting the focused localisation of strain into shear bands. To aid analysis of the structures and help derive the flow properties of rocks in the field, we define three stages of pinch and swell development and offer suggestions for measurements to be made in the field. Our study suggests that Mohr–Coulomb strain localising behaviour combined with viscous flow is a viable alternative representation of the heterogeneous rheological behaviour of rocks seen in the middle crust. This type of mid-crustal rheological behaviour can have significant influence on the localisation of strain at all scales. For example, inclusion of Mohr–Coulomb strain localising behaviour with viscous flow in just some mid-crustal layers within a crustal-scale model can result in significant strain localisation, extending from the upper crust into the middle crust. This localisation also influences the development of near-surface structures.

scholarly journals Pinch and swell structures: evidence for brittle-viscous behaviour in the middle crust

2015 ◽  
Vol 7 (2) ◽  
pp. 1517-1554
Author(s):  
R. Gardner ◽  
S. Piazolo ◽  
N. Daczko
Keyword(s):  
Viscous Flow ◽  
Lower Crust ◽  
Brittle Failure ◽  
High Strain ◽  
Rheological Behaviour ◽  
Scale Model ◽  
Flow Properties ◽  
Near Surface ◽  
Heterogeneous Rocks ◽  
The Matrix

Abstract. The flow properties of middle to lower crustal rocks are commonly represented by viscous flow. However, examples of pinch and swell structures found in a mid-crustal high strain zone at St. Anne Point (Fiordland, New Zealand) suggest pinch and swell structures are initiated by brittle failure of the more competent layer in conjunction with material softening. On this basis we develop a flexible numerical model using brittle-viscous flow where Mohr–Coulomb failure is utilised to initiate pinch and swell structure development. Results show that pinch and swell structures develop in a competent layer in both Newtonian and non-Newtonian flow provided the competent layer has enough viscosity contrast and initially fails brittlely. The degree of material softening after initial failure is shown to impact pinch and swell characteristics with high rates of material softening causing the formation of thick necks between swells by limiting the successful localisation of strain. The flow regime and yielding characteristics of the matrix do not impact pinch and swell structure formation itself, so long as the matrix is less competent. To aid analysis of the structures and help derive the flow properties of rocks in the field, we define three stages of pinch and swell development and offer suggestions for measurements to be made in the field. Our study suggests that Mohr–Coulomb behaviour combined with viscous flow is an appropriate way to represent the heterogeneous rocks of the middle to lower crust. This type of mid-crustal rheological behaviour has significant influence on the localization of strain at all scales. For example, inclusion of Mohr–Coulomb brittle failure with viscous flow in just some mid-crustal layers within a crustal scale model will result in strain localisation throughout the whole crustal section allowing the development of through-going high strain structures from the upper crust into the middle and lower crust. This localization then has a significant effect on developing near-surface structures.

Viscous-flow properties of acetone solutions of vinylidene fluoride ? tetrafluoroethylene copolymer

1983 ◽  
Vol 14 (3) ◽  
pp. 210-211
Author(s):  
B. S. Vesaite ◽  
A. Girlyavichyus ◽  
A. I. Logvinov ◽  
L. Ya. Madorskaya ◽  
A. V. Bezprozvannykh ◽  
...  
Keyword(s):  
Viscous Flow ◽  
Vinylidene Fluoride ◽  
Flow Properties

Un diatrème phréatomagmatique montérégien dans les Appalaches du Québec

1996 ◽  
Vol 33 (5) ◽  
pp. 649-655
Author(s):  
David Morin ◽  
Michel Jébrak ◽  
Robert Marquis
Keyword(s):  
Surface Water ◽  
Country Rock ◽  
Near Surface ◽  
Metasedimentary Rocks ◽  
North East ◽  
The North ◽  
Devonian Age ◽  
Fault Network ◽  
Alkaline Lamprophyres ◽  
East West

A subcircular positive magnetic anomaly and breccias affecting a basanite and its country-rock metasedimentary rocks reveal the presence of a diatreme with a diameter of approximately 420 m, at Eastman, in the Quebec Appalachians. The post-Middle Devonian age, the position in the line of the Monteregian plutons, and the basanite composition, which is comparable to that of the Cretaceous Monteregian alkaline lamprophyres, suggest that the diatreme is related to the Monteregian magmatism. It is located at the junction of two orthogonal tectonic corridors: the north-north-east Baie Verte – Brompton line and an east−west fault network along the prolongation of the Ottawa−Bonnechère Graben. These structures are zones of weakness that probably served as a conduit for the ascending magma and near-surface water to trigger phreatomagmatic eruptions.

The Influence of Intensification Pressure on the Gate Microstructure of AlSi3MgMn High Pressure Die Castings

2009 ◽  
Vol 618-619 ◽  
pp. 607-610 ◽  
Author(s):  
Somboon Otarawanna ◽  
Christopher M. Gourlay ◽  
Hans Ivar Laukli ◽  
Arne K. Dahle
Keyword(s):  
High Pressure ◽  
Die Casting ◽  
Shear Bands ◽  
Strain Localisation ◽  
Solidification Shrinkage ◽  
Intensification Pressure ◽  
Microstructural Characterisation ◽  
Die Castings ◽  
Pressure Die Casting ◽  
Gate Region

This article focuses on the influence of intensification pressure (I.P.) on the feeding through the gate during high pressure die casting (HPDC). Two values of intensification pressure, the lowest and highest possible for the HPDC machine used, were applied to cast AlSi3MgMn tensile-bar specimens. The castings produced with higher I.P. contained a lower total fraction of porosity, as expected. Microstructural characterisation of the gate region showed markedly different features in and adjacent to the gate at the two levels of I.P. used. The microstructures indicate a change in feeding mechanism with increasing I.P. At high I.P. shear band-like features exist through the gate, suggesting that strain localisation in the gate is involved in the feeding of solidification shrinkage during the I.P. stage. At low I.P. such shear bands were not observed in the gates and feeding was less effective, resulting in a higher level of porosity in the HPDC parts.

Analysis of viscous flow properties of asphalt in aging process

2016 ◽  
Vol 124 ◽  
pp. 631-638 ◽  
Author(s):  
Peilong Li ◽  
Zhan Ding ◽  
Li xia Ma ◽  
Zhen gang Feng
Keyword(s):  
Viscous Flow ◽  
Aging Process ◽  
Flow Properties

Viscous flow properties on slender cones

AIAA Journal ◽  
1965 ◽  
Vol 3 (3) ◽  
pp. 572-573
Author(s):  
R. A. PETER ◽  
M. D. HIGH ◽  
E. F. BLICK
Keyword(s):  
Viscous Flow ◽  
Flow Properties

scholarly journals Operational ocean models in the Adriatic Sea: a skill assessment

2006 ◽  
Vol 3 (6) ◽  
pp. 2087-2116
Author(s):  
J. Chiggiato ◽  
P. Oddo
Keyword(s):  
General Circulation ◽  
Three Dimensional ◽  
Circulation Model ◽  
Scale Model ◽  
Regional Models ◽  
Near Surface ◽  
Operational Systems ◽  
Forecasting System ◽  
The Mediterranean ◽  
Dimensional Picture

Abstract. In the framework of the Mediterranean Forecasting System project (MFS) sub-regional and regional numerical ocean forecasting systems performance are assessed by mean of model-model and model-data comparison. Three different operational systems have been considered in this study: the Adriatic REGional Model (AREG); the AdriaROMS and the Mediterranean Forecasting System general circulation model (MFS model). AREG and AdriaROMS are regional implementations (with some dedicated variations) of POM (Blumberg and Mellor, 1987) and ROMS (Shchepetkin and McWilliams, 2005) respectively, while MFS model is based on OPA (Madec et al., 1998) code. The assessment has been done by means of standard scores. The data used for operational systems assessment derive from in-situ and remote sensing measurements. In particular a set of CTDs covering the whole western Adriatic, collected in January 2006, one year of SST from space born sensors and six months of buoy data. This allowed to have a full three-dimensional picture of the operational forecasting systems quality during January 2006 and some preliminary considerations on the temporal fluctuation of scores estimated on surface (or near surface) quantities between summer 2005 and summer 2006. In general, the regional models are found to be colder and fresher than observations. They eventually outperform the large scale model in the shallowest locations, as expected. Results on amplitude and phase errors are also much better in locations shallower than 50 m, while degraded in deeper locations, where the models tend to have a higher homogeneity along the vertical column compared to observations. In a basin-wide overview, the two regional models show some dissimilarities in the local displacement of errors, something suggested by the full three-dimensional picture depicted using CTDs, but also confirmed by the comparison with SSTs. In locations where the regional models are mutually correlated, the aggregated mean-square-error has been found to be lower, which is a useful outcome of having several operational systems in the same region.

scholarly journals Development and evaluation of a variably saturated flow model in the global E3SM Land Model (ELM) version 1.0

2018 ◽  
Vol 11 (10) ◽  
pp. 4085-4102 ◽  
Author(s):  
Gautam Bisht ◽  
William J. Riley ◽  
Glenn E. Hammond ◽  
David M. Lorenzetti
Keyword(s):  
Soil Moisture ◽  
Flow Model ◽  
Scale Model ◽  
Richards Equation ◽  
Benchmark Problems ◽  
Spatially Explicit ◽  
Grid Cells ◽  
Saturated Flow ◽  
Near Surface ◽  
Computational Performance

Abstract. Improving global-scale model representations of near-surface soil moisture and groundwater hydrology is important for accurately simulating terrestrial processes and predicting climate change effects on water resources. Most existing land surface models, including the default E3SM Land Model (ELMv0), which we modify here, routinely employ different formulations for water transport in the vadose and phreatic zones. Clark et al. (2015) identified a variably saturated Richards equation flow model as an important capability for improving simulation of coupled soil moisture and shallow groundwater dynamics. In this work, we developed the Variably Saturated Flow Model (VSFM) in ELMv1 to unify the treatment of soil hydrologic processes in the unsaturated and saturated zones. VSFM was tested on three benchmark problems and results were evaluated against observations and an existing benchmark model (PFLOTRAN). The ELMv1-VSFM's subsurface drainage parameter, fd, was calibrated to match an observationally constrained and spatially explicit global water table depth (WTD) product. Optimal spatially explicit fd values were obtained for 79 % of global 1.9∘ × 2.5∘ grid cells, while the remaining 21 % of global grid cells had predicted WTD deeper than the observationally constrained estimate. Comparison with predictions using the default fd value demonstrated that calibration significantly improved predictions, primarily by allowing much deeper WTDs. Model evaluation using the International Land Model Benchmarking package (ILAMB) showed that improvements in WTD predictions did not degrade model skill for any other metrics. We evaluated the computational performance of the VSFM model and found that the model is about 30 % more expensive than the default ELMv0 with an optimal processor layout. The modular software design of VSFM not only provides flexibility to configure the model for a range of problem setups but also allows for building the model independently of the ELM code, thus enabling straightforward testing of the model's physics against other models.

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