Causes and consequences of asymmetric lateral plume flow during South Atlantic rifting

Volcanic rifted margins are typically associated with a thick magmatic layer of seaward dipping reflectors and anomalous regional uplift. This is conventionally interpreted as due to melting of an arriving mantle plume head at the onset of rifting. However, seaward dipping reflectors and uplift are sometimes asymmetrically distributed with respect to the subsequent plume track. Here we investigate if these asymmetries are induced by preexisting lateral variations in the thickness of continental lithosphere and/or lithospheric stretching rates, variations that promote lateral sublithospheric flow of plume material below only one arm of the extending rift. Using three-dimensional numerical experiments, we find that South Atlantic rifting is predicted to develop a strong southward asymmetry in its distribution of seaward dipping reflectors and associated anomalous relief with respect to the Tristan Plume that “drove” this volcanic rifted margin, and that the region where plume material drains into the rift should experience long-lived uplift during rifting—both as observed. We conclude that a mantle plume is still needed to source the anomalously hot sublithospheric material that generates a volcanic rifted margin, but lateral along-rift flow from this plume, not a broad starting plume head, is what controls when and where a volcanic rifted margin will form.

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Melt volume at Atlantic volcanic rifted margins controlled by depth-dependent extension and mantle temperature

Nature Communications ◽

10.1038/s41467-021-23981-5 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Gang Lu ◽

Ritske S. Huismans

Keyword(s):

Numerical Models ◽

Potential Temperature ◽

Analytical Prediction ◽

Natural Systems ◽

Passive Margins ◽

Margin Width ◽

Rifted Margins ◽

Mantle Potential Temperature ◽

Mantle Temperature ◽

Rifted Margin

AbstractBreakup volcanism along rifted passive margins is highly variable in time and space. The factors controlling magmatic activity during continental rifting and breakup are not resolved and controversial. Here we use numerical models to investigate melt generation at rifted margins with contrasting rifting styles corresponding to those observed in natural systems. Our results demonstrate a surprising correlation of enhanced magmatism with margin width. This relationship is explained by depth-dependent extension, during which the lithospheric mantle ruptures earlier than the crust, and is confirmed by a semi-analytical prediction of melt volume over margin width. The results presented here show that the effect of increased mantle temperature at wide volcanic margins is likely over-estimated, and demonstrate that the large volumes of magmatism at volcanic rifted margin can be explained by depth-dependent extension and very moderate excess mantle potential temperature in the order of 50–80 °C, significantly smaller than previously suggested.

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Acceleration of the EM-like reconstruction method for diffuse optical tomography with ordered-subsets method

Journal of Inverse and Ill-Posed Problems ◽

10.1515/jip-2012-0064 ◽

2014 ◽

Vol 22 (3) ◽

Author(s):

Caifang Wang

Keyword(s):

Numerical Experiments ◽

Imaging Modality ◽

Random Medium ◽

Optical Tomography ◽

Back Propagation ◽

Three Dimensional ◽

Diffuse Optical Tomography ◽

Optical Parameters ◽

Reconstruction Method ◽

Boundary Measurements

Abstract.Diffuse optical tomography (DOT) is an optical imaging modality, which provides the spatial distribution of the optical parameters inside a random medium. A propagation back-propagation method named EM-like reconstruction method for stationary DOT problem has been proposed yet. This method is really time consuming. Hence the ordered-subsets (OS) technique for this reconstruction method is studied in this paper. The boundary measurements of DOT are grouped into nonoverlapping and overlapping ordered sequence of subsets with random partition, sequential partition and periodic partition, respectively. The performance of OS methods is compared with the standard EM-like reconstruction method with two-dimensional and three-dimensional numerical experiments. The numerical experiments indicate that reconstruction of nonoverlapping subsets with periodic partition, overlapping subsets with periodic partition and standard EM-like method provide very similar acceptable reconstruction results. However, reconstruction of nonoverlapping subsets with periodic partition spends a minimum of time to get proper results.

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Reconstruction of the Reservoir Fine Structure by Using Scattering Attributes

10.2118/206083-ms ◽

2021 ◽

Author(s):

Vladimir Cheverda ◽

Vadim Lisitsa ◽

Maksim Protasov ◽

Galina Reshetova ◽

Andrey Ledyaev ◽

...

Keyword(s):

Seismic Data ◽

Numerical Experiments ◽

Seismic Waves ◽

Fractured Reservoirs ◽

Three Dimensional ◽

Geological Structure ◽

Discrete Elements ◽

Digital Twin ◽

The North ◽

Slip Surfaces

Abstract To develop the optimal strategy for developing a hydrocarbon field, one should know in fine detail its geological structure. More and more attention has been paid to cavernous-fractured reservoirs within the carbonate environment in the last decades. This article presents a technology for three-dimensional computing images of such reservoirs using scattered seismic waves. To verify it, we built a particular synthetic model, a digital twin of one of the licensed objects in the north of Eastern Siberia. One distinctive feature of this digital twin is the representation of faults not as some ideal slip surfaces but as three-dimensional geological bodies filled with tectonic breccias. To simulate such breccias and the geometry of these bodies, we performed a series of numerical experiments based on the discrete elements technique. The purpose of these experiments is the simulation of the geomechanical processes of fault formation. For the digital twin constructed, we performed full-scale 3D seismic modeling, which made it possible to conduct fully controlled numerical experiments on the construction of wave images and, on this basis, to propose an optimal seismic data processing graph.

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A Triggering Mechanism for Rapid Intensification of Tropical Cyclones

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-14-0193.1 ◽

2015 ◽

Vol 72 (7) ◽

pp. 2666-2681 ◽

Cited By ~ 28

Author(s):

Yoshiaki Miyamoto ◽

Tetsuya Takemi

Keyword(s):

Boundary Layer ◽

Numerical Experiments ◽

Axisymmetric Flow ◽

Three Dimensional ◽

Tangential Velocity ◽

Convective Cell ◽

Rapid Intensification ◽

Rotating Fluid ◽

Coriolis Parameter ◽

Maximum Tangential Velocity

Triggering processes for the rapidly intensifying phase of a tropical cyclone (TC) were investigated on the basis of numerical experiments using a three-dimensional nonhydrostatic model. The results revealed that the rapid intensification of the simulated TC commenced following the formation of a circular cloud, which occurred about 12 h after the TC became essentially axisymmetric. The circular cloud (eyewall) evolved from a cloudy convective cell that was originally generated near the radius of maximum wind speed (RMW). The development of the convective cell in the eyewall was closely related to the radial location of the strong boundary layer convergence of axisymmetric flow. The radius of maximum convergence (RMC) was small relative to the RMW when the TC vortex was weak, which is consistent with the boundary layer theory for a rotating fluid system on a frictional surface. As the TC intensified, the RMC approached the RMW. An eyewall was very likely to form in the simulated TC when the RMC approached the RMW. Because the RMC is theoretically determined by a Rossby number defined by the maximum tangential velocity, RMW, and Coriolis parameter, a series of numerical experiments was conducted by changing the three parameters. The results were consistent with the hypothesis that intensification occurs earlier for larger Rossby numbers. This finding indicates that initial TC vortices with larger Rossby numbers are more likely to experience rapid intensification and, hence, to evolve into strong hurricanes.

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Three-dimensional Numerical Experiments on Hydrodynamics in Taihu Lake-3.Influence of the Reclaimation in Mashan Districton Wind-driven Current

Journal of Lake Sciences ◽

10.18307/2000.0407 ◽

2000 ◽

Vol 12 (4) ◽

pp. 335-342 ◽

Cited By ~ 1

Author(s):

HU Weiping ◽

◽

QIN Boqiang ◽

PU Peimin

Keyword(s):

Numerical Experiments ◽

Taihu Lake ◽

Three Dimensional

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Rift inheritance controls the switch from thin- to thick-skinned thrusting and basal décollement re-localization at the subduction-to-collision transition

Geological Society of America Bulletin ◽

10.1130/b35800.1 ◽

2021 ◽

Author(s):

Stefano Tavani ◽

Pablo Granado ◽

Amerigo Corradetti ◽

Giovanni Camanni ◽

Gianluca Vignaroli ◽

...

Keyword(s):

Sedimentary Cover ◽

Complete Removal ◽

Lower Plate ◽

Accretionary Wedge ◽

Convergent Margins ◽

Middle Crust ◽

Rifted Margins ◽

Thrust System ◽

Structural Levels ◽

Rifted Margin

In accretionary convergent margins, the subduction interface is formed by a lower plate décollement above which sediments are scraped off and incorporated into the accretionary wedge. During subduction, the basal décollement is typically located within or at the base of the sedimentary pile. However, the transition to collision implies the accretion of the lower plate continental crust and deformation of its inherited rifted margin architecture. During this stage, the basal décollement may remain confined to shallow structural levels as during subduction or re-localize into the lower plate middle-lower crust. Modes and timing of such re-localization are still poorly understood. We present cases from the Zagros, Apennines, Oman, and Taiwan belts, all of which involve a former rifted margin and point to a marked influence of inherited rift-related structures on the décollement re-localization. A deep décollement level occurs in the outer sectors of all of these belts, i.e., in the zone involving the proximal domain of pre-orogenic rift systems. Older—and shallower—décollement levels are preserved in the upper and inner zones of the tectonic pile, which include the base of the sedimentary cover of the distal portions of the former rifted margins. We propose that thinning of the ductile middle crust in the necking domains during rifting, and its complete removal in the hyperextended domains, hampered the development of deep-seated décollements during the inception of shortening. Progressive orogenic involvement of the proximal rift domains, where the ductile middle crust was preserved upon rifting, favors its reactivation as a décollement in the frontal portion of the thrust system. Such décollement eventually links to the main subduction interface, favoring underplating and the upward motion of internal metamorphic units, leading to their final emplacement onto the previously developed tectonic stack.

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Planet migration and magnetic torques

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316002325 ◽

2015 ◽

Vol 11 (A29A) ◽

pp. 14-18

Author(s):

A. Strugarek ◽

A. S. Brun ◽

S. P. Matt ◽

V. Reville

Keyword(s):

Numerical Experiments ◽

Three Dimensional ◽

Magnetic Star ◽

Magnetic Topology ◽

Global Models ◽

Planet Migration ◽

Order Of Magnitude ◽

Ideal Magnetohydrodynamic ◽

The Impact ◽

The Ideal

AbstractThe possibility that magnetic torques may participate in close-in planet migration has recently been postulated. We develop three dimensional global models of magnetic star-planet interaction under the ideal magnetohydrodynamic (MHD) approximation to explore the impact of magnetic topology on the development of magnetic torques. We conduct twin numerical experiments in which only the magnetic topology of the interaction is altered. We find that magnetic torques can vary by roughly an order of magnitude when varying the magnetic topology from an aligned case to an anti-aligned case. Provided that the stellar magnetic field is strong enough, we find that magnetic migration time scales can be as fast as ~100 Myr. Hence, our model supports the idea that magnetic torques may participate in planet migration for some close-in star-planet systems.

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Aerodynamic Behavior of Asymmetric Jets in 3-D Furnaces

Volume 3: Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations ◽

10.1115/94-gt-441 ◽

1994 ◽

Author(s):

F. M. El-Mahallawy ◽

M. A. Hassan ◽

M. A. Ismail ◽

H. Zafan

Keyword(s):

Numerical Simulation ◽

Flow Pattern ◽

Numerical Experiments ◽

Recirculation Zone ◽

Reverse Flow ◽

Three Dimensional ◽

Flow Region ◽

Stabilization Method ◽

Flow Features

The purpose of this paper is to present and evaluate numerical experiments illustrating the flow features in a 3-D furnace utilizing unconventional asymmetrical jet that creates natural recirculation zone. The numerical simulation of this aerodynamic stabilization method have unveiled the three-dimensional nature of the flow pattern which possesses a quite large reverse flow region. The size and strength of the built recirculation zone would be capable of stabilizing the burning of low-quality fuels.

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