scholarly journals Introduction: Active Margins in Transition—Magmatism and Tectonics through Time: An Issue in Honor of Arthur W. Snoke

Geosphere ◽  
2021 ◽  
Author(s):  
Allen J. McGrew ◽  
Joshua J. Schwartz
Keyword(s):  
Boundary Conditions ◽  
Plate Tectonics ◽  
Time And Space ◽  
Active Margin ◽  
Broad Scope ◽  
Active Margins

The evolution of active margins through time is the record of plate tectonics as inscribed on the continents. This themed issue honors the eclectic contributions of Arthur W. Snoke (Fig. 1) to the study of active margins with a series of papers that amply demonstrate the broad scope of active margin tectonics and the diverse methods that tectonic geologists employ to decipher their histories. Taken together, this set of papers illustrates the diversity of boundary conditions that guide the development of active margins and the key parameters that regulate their evolution in time and space.

scholarly journals Mixed thermal conditions in convection: how do continents affect the mantle’s circulation?

2017 ◽  
Vol 822 ◽  
pp. 1-4 ◽  
Author(s):  
R. Ostilla-Mónico
Keyword(s):  
Boundary Conditions ◽  
Plate Tectonics ◽  
Large Scale ◽  
Thermal Conditions ◽  
Experimental Proof ◽  
Bénard Convection ◽  
Benard Convection ◽  
Large Scale Flow ◽  
Rayleigh Benard Convection ◽  
Rayleigh Benard

Natural convection is omnipresent on Earth. A basic and well-studied model for it is Rayleigh–Bénard convection, the fluid flow in a layer heated from below and cooled from above. Most explorations of Rayleigh–Bénard convection focus on spatially uniform, perfectly conducting thermal boundary conditions, but many important geophysical phenomena are characterized by boundary conditions which are a mixture of conducting and adiabatic materials. For example, the differences in thermal conductivity between continental and oceanic lithospheres are believed to play an important role in plate tectonics. To study this, Wang et al. (J. Fluid Mech., vol. 817, 2017, R1), measure the effect of mixed adiabatic–conducting boundary conditions on turbulent Rayleigh–Bénard convection, finding experimental proof that even if the total heat transfer is primarily affected by the adiabatic fraction, the arrangement of adiabatic and conducting plates is crucial in determining the large-scale flow dynamics.

scholarly journals Neotectonic mountain uplift and geomorphology

2019 ◽  
pp. 3-26
Author(s):  
C. D. Ollier ◽  
C. F. Pain
Keyword(s):  
Plate Tectonics ◽  
Volcanic Rocks ◽  
Passive Margin ◽  
Continental Margins ◽  
Lateral Compression ◽  
Mountain Building ◽  
Topographic Features ◽  
Active Margins ◽  
The World ◽  
Fold Belts

Mountains are topographic features caused by erosion after vertical uplift or mountain building. Mountain building is often confused with orogeny, which today means the formation of structures in fold belts. The common assumption that folding and mountain building go together is generally untrue. Many mountains occur in unfolded rocks, granites and volcanic rocks, so there is no direct association of folding and mountain building. In those places where mountains are underlain by folded rocks the folding pre-dates planation and uplift. The age of mountains is therefore not the age of the last folding (if any) but the age of vertical uplift. Since mountains are not restricted to folded rocks, lateral compression is not required to explain the uplift. A compilation of times of uplift of mountains around the world shows that a major phase of tectonic uplift started about 6 Ma, and much uplift occurred in the last 2 Ma. This period is known as the Neotectonic Period. It is a global phenomenon including mountains on passive continental margins, and those in deep continental interiors. Several hypotheses of mountain building have problems with this timing. Some fail by being only able to make mountains out of folded rock at continental margins. Many translate the vertical uplift into lateral compression, but vertical uplift alone can create mountains. The Neotectonic Period has important implications for geomorphology, climate and global tectonics. In geomorphology it does not fit into conventional theories of geomorphology such as Davisian or King cycles of erosion. Neotectonic uplift might initiate several cycles of erosion, but most planation surfaces are much older than the Neotectonic Period. The increasing relief associated with Neotectonic uplift affected rates of erosion and sedimentation, and also late Cenozoic climate. The Neotectonic Period does not fit within plate tectonics theory, in which mountains are explained as a result of compression at active margins: mountains in other locations are said to have been caused by the same process but further back in time. This is disproved by the young age of uplift of mountains in intercontinental and passive margin positions. Subduction is supposed to have been continuous for hundreds of millions of years, so fails to explain the world-wide uplifts in just a few million years. Geomorphologists should be guided by their own findings, and refrain from theory-driven hypotheses of plate collision or landscape evolution.

The Teton – Wind River domain: a 2.68–2.67 Ga active margin in the western Wyoming Province

2006 ◽  
Vol 43 (10) ◽  
pp. 1489-1510 ◽  
Author(s):  
B Ronald Frost ◽  
Carol D Frost ◽  
Mary Cornia ◽  
Kevin R Chamberlain ◽  
Robert Kirkwood
Keyword(s):  
Plate Tectonics ◽  
Accretionary Prism ◽  
Granulite Facies ◽  
Isotopic Data ◽  
Active Margin ◽  
Magmatic Arc ◽  
Wind River Range ◽  
Teton Range ◽  
Wyoming Province ◽  
Back Arc

The Archean rocks in western Wyoming, including the Teton Range, the northern Wind River Range, and the western Owl Creek Mountains, preserve a record of a 2.68–2.67 Ga orogenic belt that has many of the hallmarks of modern plate tectonics. A 2683 Ma tholeiitic dike swarm is undeformed and unmetamorphosed in the western Owl Creek Mountains. In the Wind River Range, these dikes have been deformed and metamorphosed during thrusting along the west- to southwest-directed Mount Helen structural belt, which was active at the time that the 2.67 Ga Bridger batholith was emplaced. In the northern Teton Range, the Moose Basin gneiss, which contains relict granulite-facies assemblages, appears to have been thrust upon the amphibolite-grade layered gneiss. The syntectonic Webb Canyon orthogneiss was intruded into the thrust at or before 2673 Ma. We interpret these relations, along with isotopic data indicating that the layered gneiss in the Teton Range consists of juvenile components, to indicate that the western Wyoming Province was the site of active margin tectonics at 2.68–2.67 Ga. This involved a magmatic arc in the present Wind River Range and back-arc spreading in the Owl Creek Mountains. The immature, juvenile layered gneiss in the Teton Range probably represents an accretionary prism or fore-arc basin onto which high-pressure rocks containing a mature sedimentary sequence were thrust at 2.67 Ga. Although it may be questioned as to when modern-style plate tectonics began in other cratons, it was certainly operating in the Wyoming Province by 2.67 Ga.

scholarly journals Phase Evolution of the Time- and Space-Like Peregrine Breather in a Laboratory

Fluids ◽  
2021 ◽  
Vol 6 (9) ◽  
pp. 308
Author(s):  
Yuchen He ◽  
Pierre Suret ◽  
Amin Chabchoub
Keyword(s):  
Boundary Conditions ◽  
Phase Evolution ◽  
Wave Localization ◽  
Time And Space ◽  
Wave Groups ◽  
Phase Dynamics ◽  
Wave Flume ◽  
Coherent Wave ◽  
Intrinsic Shape ◽  
Peregrine Breather

Coherent wave groups are not only characterized by the intrinsic shape of the wave packet, but also by the underlying phase evolution during the propagation. Exact deterministic formulations of hydrodynamic or electromagnetic coherent wave groups can be obtained by solving the nonlinear Schrödinger equation (NLSE). When considering the NLSE, there are two asymptotically equivalent formulations, which can be used to describe the wave dynamics: the time- or space-like NLSE. These differences have been theoretically elaborated upon in the 2016 work of Chabchoub and Grimshaw. In this paper, we address fundamental characteristic differences beyond the shape of wave envelope, which arise in the phase evolution. We use the Peregrine breather as a referenced wave envelope model, whose dynamics is created and tracked in a wave flume using two boundary conditions, namely as defined by the time- and space-like NLSE. It is shown that whichever of the two boundary conditions is used, the corresponding local shape of wave localization is very close and almost identical during the evolution; however, the respective local phase evolution is different. The phase dynamics follows the prediction from the respective NLSE framework adopted in each case.

scholarly journals INVERSE PROBLEM TO DETERMINE DEGENERATE MEMORY KERNELS IN HEAT FLUX WITH THIRD KIND BOUNDARY CONDITIONS

2006 ◽  
Vol 11 (4) ◽  
pp. 427-450 ◽  
Author(s):  
E. Pais ◽  
J. Janno
Keyword(s):  
Heat Flux ◽  
Inverse Problem ◽  
Boundary Conditions ◽  
Internal Energy ◽  
Existence And Uniqueness ◽  
Temperature Measurements ◽  
Time And Space ◽  
Uniqueness Of A Solution

An inverse problem to determine degenerate time‐ and space‐dependent relaxation kernels of internal energy and heat flux with third kind boundary conditions by means of temperature measurements is considered. Existence and uniqueness of a solution to the inverse problem are proved.

Space, Time, and Causality

2017 ◽  
Author(s):  
Marc J. Buehner
Keyword(s):  
Boundary Conditions ◽  
Space Time ◽  
Temporal Information ◽  
Causal Beliefs ◽  
Time And Space ◽  
Causal Inferences ◽  
Causal Belief ◽  
Cause And Effect ◽  
Recent Developments ◽  
Perception Of Time

This chapter explores how the understanding of causality relates to the understanding of space and time. Traditionally, spatiotemporal contiguity is regarded as a cue toward causality. While concurring with this view, this chapter also reviews some boundary conditions of this approach. Moreover, temporal information goes beyond merely helping to identify causal relations; it also shapes the types of causal inferences that reasoners draw. Recent developments further show that the relation between time and causality is bi-directional: not only does temporal information shape and guide causal inferences, but once one holds a causal belief, one’s perception of time and space is distorted such that cause and effect appear closer in space-time. Spatiotemporal contiguity thus supports causal beliefs, which in turn foster impressions of contiguity.

Use of the Magnetostatic Analogue In Electromagnetic Lens Engineering

1970 ◽  
Vol 28 ◽  
pp. 360-361
Author(s):  
John W. Coleman
Keyword(s):  
Boundary Conditions ◽  
High Performance ◽  
Force Fields ◽  
Optical Design ◽  
Direct Conversion ◽  
Design Engineering ◽  
Design Data ◽  
Scalar Potentials ◽  
Geometric Elements ◽  
At Will

In the design engineering of high performance electromagnetic lenses, the direct conversion of electron optical design data into drawings for reliable hardware is oftentimes difficult, especially in terms of how to mount parts to each other, how to tolerance dimensions, and how to specify finishes. An answer to this is in the use of magnetostatic analytics, corresponding to boundary conditions for the optical design. With such models, the magnetostatic force on a test pole along the axis may be examined, and in this way one may obtain priority listings for holding dimensions, relieving stresses, etc..The development of magnetostatic models most easily proceeds from the derivation of scalar potentials of separate geometric elements. These potentials can then be conbined at will because of the superposition characteristic of conservative force fields.

A digital vocal tract simulator with boundary conditions at lips and glottis

1981 ◽  
Vol 64 (11) ◽  
pp. 18-26 ◽  
Author(s):  
Tetsuya Nomura ◽  
Nobuhiro Miki ◽  
Nobuo Nagai
Keyword(s):  
Boundary Conditions ◽  
Vocal Tract
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