Flow in the Earth's mantle causes the preferred orientation of crystals called lattice/crystal preferred orientation (LPO or CPO). This preferred orientation is one of the main reasons why seismic anisotropy is observed. Seismic anisotropy observations could therefore be used to constrain the mantle flow in geodynamic models through tracking CPO evolution, and computing the resulting elastic tensor and the anisotropy predicted at the surface. Even though there are many types of CPO models, only a few studies include CPO calculations due to the complexity and computational cost. Here, we implemented an extended version of the CPO model D‐Rex into the open‐source community geodynamics code
Using a 3‐D mantle wedge flow field for a generic oblique subduction system, we calculate elastic tensors of mineral aggregates in the mantle wedge for A‐, B‐, C‐, and E‐type olivine crystal preferred orientations (CPO) and apply the calculated elastic tensor in the forward calculation of shear‐wave splitting (SWS) through the mantle wedge. We find that the hexagonal approximation of the full tensor does not affect the SWS parameters (the fast direction and the delay time) significantly for all CPO types except that the delay time for C‐type CPO becomes shorter. Additionally, we find that despite the 3‐D mantle flow field that results from oblique subduction, the fast direction is margin‐normal for A‐, C‐ and E‐type CPOs and margin‐parallel for B‐type CPO.
more » « less- NSF-PAR ID:
- 10375830
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 49
- Issue:
- 20
- ISSN:
- 0094-8276
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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