Juliane Dannberg 1 , Timo Heister 2 1 Texas A&M University, 2 - - PowerPoint PPT Presentation

Juliane Dannberg1, Timo Heister2

1Texas A&M University, 2Clemson University

MANTLE CONVECTION

From Hong Kong Geological Survey

heating cooling buoyancy- driven flow

MANTLE PLUMES

Modified from Putirka et al., 2011

mass extinction magmatism heat transport mantle convection thermal anomaly

From Griffiths and Campbell, 1990

MANTLE CONVECTION: : MELTING

From Hong Kong Geological Survey 1 2 3

MELT MIG IGRATION

Subduction zones Wilson et al, 2014 1 Katz, 2008 Mid-ocean ridges 2 Keller et al, 2013 Fractures/channels/diapirs 3

 Studies only in 2D / simplified  Mantle convection and melt migration

studied separately

VARIABLES

density shear viscosity compaction viscosity Darcy coefficient solid fluid/ melt

EQUATIONS

η,ξ = f(φ) KD ~ φ3

EQUATIONS

Introduce compaction pressure (Keller at al, 2013):

EQUATIONS IN IN ASPECT

EQUATIONS IN IN ASPECT

CHALLENGES

 Time and length scales of melt

migration are vastly different from mantle convection

 Highly non-linear and spatially

variable material properties

• Difficult to study in 3D
• Adaptive mesh refinement

 Link melt generation to processes in the

deeper mantle (komatiites or other melts originating in greater depths)

• Compressibility

SO SOFTWARE: ASP SPECT

Advanced mathematical techniques:

 Higher order time stepping schemes (BDF2)  Higher order finite elements  Fully adaptive, dynamically changing 3d

meshes

 Nonlinear solvers  Parallelization using MPI, threads, and tasks

Community code:

 Modular  Extensive documentation  Extensive and frequent testing

MODULARITY

Aspect is very modular: It is extended by a number of isolated “plugin” sub-systems:

Aspect core Postprocessing Visualization Geometry Initial cond. Boundary cond. Material model Gravity Termination Mesh refinement Public interface

DEAL.I .II FEATURES

Aspect core Postprocessing Visualization Geometry Initial cond. Boundary cond. Material model Gravity Termination Mesh refinement Public interface

Solver (AMG), Interfaces to PETSC, Trilinos Write output in common visualization file formats, parallel I/O Adaptive meshes in 2D & 3D, refinement indicators Higher order finite elements, several components Finite element meshes, manifolds Checkpoint / Restart Parallel, scaling up to 10,000s of cores Flexible: no slip, free slip, traction, Dirichlet, periodic

CONVERGENCE WIT ITH ADAPTIVE MESH

Porosity Fluid pressure Velocity

CONVERGENCE WIT ITH ADAPTIVE MESH

SH SHEAR BANDS

Boundary velocity Boundary velocity

SH SHEAR BANDS: : ANGLE

SH SHEAR BANDS IN IN 3D

Total wallclock time: 1.7 hours 130 time steps; t=3.125e-08 years Number of degrees of freedom: 44,855,815

MANTLE PLUME WIT ITH MELT MIGRATION

Wallclock time: 7 days 14200 time steps; t=152,516 years Degrees of freedom: 6,243,260

MANTLE PLUME WIT ITH MELT

MANTLE PLUME WIT ITH MELT

3D PLUME: : WORK IN IN PROGRESS

APPLICATIONS

CONCLUSIONS

 Open source code for coupled magma / mantle dynamics  Uses modern numerical methods  Accurate  Fast, scalable  Well tested, well documented  Designed to be easily extended  Has been successfully applied to several application cases

• On different scales
• In three dimensions
• With compressibility of the individual phases

ASP SPECT TEAM