Linear gradient in Initial Composition and resulting density interpolation

ASPECT
1

Hello ASPECT community!

I am currently working on continental extension cookbook using the Boussinesq approximation.

My 2-D model setup involves two mantle lithosphere domains (East and West) with different degrees of depletion, which I intend to represent using different reference densities. I have introduced a transition zone between these two domains.

I have a few specific questions regarding this implementation:

  1. Initial Composition: Does the Initial composition model in ASPECT support defining a linear gradient across the transition zone (i.e., linearly varying the composition field value from 0 to 1)?

  2. Density Calculation: If a linear gradient is applied to the composition, will the resulting density also be interpolated linearly between the two reference densities?

Thank you for your advice.

Xiangwu

2

Hi Xiangwu,

Thanks for posting and welcome to the community! In short, the answer to both of your questions is yes. For something like you described, you can achieve this using the “Function” Initial composition model and specify exactly the width of the linear region. Within the linear region where both “mantle" compositions are non-zero, the density will be determined based on the averaging method you choose in the Material model. I hope this helps!

Cheers,

Daniel

3

Hi Daniel,

Thank you for the quick reply and clear explanation!

It is great to know that the “Function” Initial composition model can handle the linear gradient I need. This is very helpful for my setup. Thanks again!

Best,

Xiangwu