Predictive modelling of seismic properties in single-foliated slates

Abstract

Slates play a key role in understanding the seismic anisotropy of the continental crust, a crucial aspect of geophysical interpretation. Using a comprehensive set of high-quality single-foliated roofing slates, we determined their typical seismic properties via mineral fractions and orientation distribution functions using the VRH averaging method. Our study focused on identifying optimal polar (transverse isotropy) models, assess correlations between elastic constants, and explore the feasibility of predicting intrinsic maximum anisotropy from a single proxy. We demonstrate that axial and polarization anisotropy in single-foliated slates can be accurately estimated with ~10% error using a single proxy, termed the S-norm, which integrates the ODF strength and volumetric fraction of phyllosilicates. Additionally, we found that a polar parameterization combining elastic tensor decomposition and the Anderson equations yields seismic anisotropy predictions similar to the Christoffel equation, with errors below 3% (<0.3% for Vp). Lastly, our findings suggest that it is feasible to estimate the seismic properties of transversely isotropic slates from only two measurements: a diagonal component and the non-diagonal C13 component. These models are applicable for investigating slate belts at various depths, enabling the calculation of the minimum expected seismic anisotropy from intrinsic properties.