scholarly journals The interaction between mantle plumes and lithosphere and its surface expressions: 3-D numerical modelling

2021 ◽  
Vol 225 (2) ◽  
pp. 906-925
Author(s):  
Yongming Wang ◽  
Mingming Li

SUMMARY The rise of mantle plumes to the base of the lithosphere leads to observable surface expressions, which provide important information about the deep mantle structure. However, the process of plume–lithosphere interaction and its surface expressions remain not well understood. In this study, we perform 3-D spherical numerical simulations to investigate the relationship between surface observables induced by plume–lithosphere interaction (including dynamic topography, geoid anomaly and melt production rate) and the physical properties of plume and lithosphere (including plume size, plume excess temperature, plume viscosity, and lithosphere viscosity and thickness). We find that the plume-induced surface expressions have strong spatial and temporal variations. Before reaching the base of the lithosphere, the rise of a plume head in the deep mantle causes positive and rapid increase of dynamic topography and geoid anomaly at the surface but no melt production. The subsequent impinging of a plume head at the base of the lithosphere leads to further increase of dynamic topography and geoid anomaly and causes rapid increase of melt production. After reaching maximum values, these plume-induced observables become relatively stable and are more affected by the plume conduit. In addition, whereas the geoid anomaly and dynamic topography decrease from regions above the plume centre to regions above the plume edge, the melt production always concentrates at the centre part of the plume. We also find that the surface expressions have different sensitivities to plume and lithosphere properties. The dynamic topography significantly increases with the plume size, plume excess temperature and plume viscosity. The geoid anomaly also increases with the size and excess temperature of the plume but is less sensitive to plume viscosity. Compared to the influence of plume properties, the dynamic topography and geoid anomaly are less affected by lithosphere viscosity and thickness. The melt production significantly increases with plume size, plume excess temperature and plume viscosity, but decreases with lithosphere viscosity and thickness.

2011 ◽  
Vol 65 (12) ◽  
pp. 1293-1297
Author(s):  
Keiko Hashiguchi ◽  
Takehiro Yoshimatsu ◽  
Masanori Kawashima

Author(s):  
Lovel Kukuljan ◽  
Franci Gabrovšek ◽  
Matthew D. Covington ◽  
Vanessa E. Johnston

AbstractUnderstanding the dynamics and distribution of CO2 in the subsurface atmosphere of carbonate karst massifs provides important insights into dissolution and precipitation processes, the role of karst systems in the global carbon cycle, and the use of speleothems for paleoclimate reconstructions. We discuss long-term microclimatic observations in a passage of Postojna Cave, Slovenia, focusing on high spatial and temporal variations of pCO2. We show (1) that the airflow through the massif is determined by the combined action of the chimney effect and external winds and (2) that the relationship between the direction of the airflow, the geometry of the airflow pathways, and the position of the observation point explains the observed variations of pCO2. Namely, in the terminal chamber of the passage, the pCO2 is low and uniform during updraft, when outside air flows to the site through a system of large open galleries. When the airflow reverses direction to downdraft, the chamber is fed by inlets with diverse flow rates and pCO2, which enter via small conduits and fractures embedded in a CO2-rich vadose zone. If the spatial distribution of inlets and outlets produces minimal mixing between low and high pCO2 inflows, high and persistent gradients in pCO2 are formed. Such is the case in the chamber, where vertical gradients of up to 1000 ppm/m are observed during downdraft. The results presented in this work provide new insights into the dynamics and composition of the subsurface atmosphere and demonstrate the importance of long-term and spatially distributed observations.


1994 ◽  
Vol 264 ◽  
pp. 81-106 ◽  
Author(s):  
J. Verron ◽  
S. Valcke

The influence of stratification on the merging of like-sign vortices of equal intensity and shape is investigated by numerical simulations in a quasi-geostrophic, two-layer stratified model. Two different types of vortices are considered: vortices defined as circular patches of uniform potential vorticity in the upper layer but no PV anomaly in the lower layer (referred to as PVI vortices), and vortices defined as circular patches of uniform relative vorticity in the upper layer but no motion in the lower layer (referred to as RVI vortices). In particular, it is found that, in the RVI case, the merging behaviour depends strongly on the magnitude of the stratification (i.e. the ratio of internal Rossby radius and vortex radius). The critical point here appears to be whether or not the initial eddies have a deep flow signature in terms of PV.The specific phenomenon of scale-dependent merging observed is interpreted in terms of the competitive effects of hetonic interaction and vortex shape. In the case of weaker stratification, the baroclinic structure of the eddies can be seen as dominated by a mechanism of hetonic interaction in which bottom flow appears to counteract the tendency of surface eddies to merge. In the case of larger stratification, the eddy interaction mechanism is shown to be barotropically dominated, although interface deformation still determines the actual eddy vorticity profile during the initialization stage. Repulsion (hetonic) effect therefore oppose attraction (barotropic shape) effects in a competitive process dependent on the relationship between the original eddy lengthscale and the first internal Rossby radius.A concluding discussion considers the implications of such analysis for real situations, in the ocean or in the laboratory.


2012 ◽  
Vol 501 ◽  
pp. 442-447
Author(s):  
Ping Fu ◽  
Feng Bao Bai ◽  
Chuan Sheng Wang ◽  
Shan Hu Li

In this paper adopting the orthogonal method, self-developed compound formulation had tested, and the relationship between the physical properties of vulcanized rubber and rectangular synchronous rotor mixer parameters had researched. The results showed that when the fill factor was 0.6, the rotor speed was 70r/min, cooling water temperature was 45 °C, pressure on the top bolt was 0.8Mpa, the physical properties of the vulcanized rubber was best.


2017 ◽  
Vol 26 (3) ◽  
pp. 179-190
Author(s):  
Igor Boyko ◽  
Liudmyla Skochko ◽  
Veronica Zhuk

Abstract The interaction features of multi-level retaining walls with soil base were researched by changing their geometric parameters and locality at the plan. During excavation of deep foundation pits it is important to choose the type of constructions which influences on the horizontal displacements. The distance between the levels of retaining walls should be based on the results of numerical modelling. The objective of this paper is to present a comparison between the data of numerical simulations and the results of the in-situ lateral tests of couple piles. The problems have been solved by using the following soil models: Coulomb-Mohr model; model, which is based on the dilatation theory; elastic-plastic model with variable stiffness parameters.


Author(s):  
E. Amah ◽  
N. Musunuri ◽  
Ian S. Fischer ◽  
Pushpendra Singh

We numerically study the process of self-assembly of particle mixtures on fluid-liquid interfaces when an electric field is applied in the direction normal to the interface. The force law for the dependence of the electric field induced dipole-dipole and capillary forces on the distance between the particles and their physical properties obtained in an earlier study by performing direct numerical simulations is used for conducting simulations. The inter-particle forces cause mixtures of nanoparticles to self-assemble into molecular-like hierarchical arrangements consisting of composite particles which are organized in a pattern. However, there is a critical electric intensity value below which particles move under the influence of Brownian forces and do not self-assemble. Above the critical value, when the particles sizes differed by a factor of two or more, the composite particle has a larger particle at its core and several smaller particles forming a ring around it. Approximately same sized particles, when their concentrations are approximately equal, form binary particles or chains (analogous to polymeric molecules) in which positively and negatively polarized particles alternate, but when their concentrations differ the particles whose concentration is larger form rings around the particles with smaller concentration.


1998 ◽  
Vol 1998 ◽  
pp. 32-32
Author(s):  
F.J. Lewis ◽  
J. McEvoy ◽  
K.J. McCracken

Whilst wheat is a major component in many pig diets it has the most variable composition of any of the cereals (Bolton & Blair, 1974) with wheat variety and the environment in which it was grown influencing its chemical and physical properties and thus nutritive value. A rapid and inexpensive method for prediction of nutritive value is thus needed to account for these variations in wheat composition. Viscosity is closely related to the soluble arabinoxylan content of wheat (Dusel et al., 1997) with a high in vitro wheat viscosity associated with a reduction in apparent metabolisable energy (AME) for poultry (Classen et al, 1995). The relationship between viscosity and nutritive value for pigs is therefore of interest. The present study investigated the effect of wheat quality measured by extract viscosity, on ileal and overall digestibility using the post-valve ‘T’ caecal (PVTC) canulation method in growing pigs.


Author(s):  
Tatsuya Matsumoto ◽  
Kensuke Tobitani ◽  
Yusuke Tani ◽  
Hiroki Fujii ◽  
Noriko Nagata

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