Recent geodynamica items

CPO2Hill: An Efficient Parametrisation to Infer Anisotropic Viscous Behaviour Directly from Olivine Texture Parameters

Mon, 15 Jun 2026 00:00:00 +0000

Anisotropic viscosity is likely prevalent within the upper mantle, but is usually disregarded in geodynamics models. On a crystal scale, olivine’s intrinsic properties are such that dislocation creep occurs over an order of magnitude more easily along olivine’s [100] symmetry axis than along its [001] axis. However, deforming olivine aggregates generate crystallographic preferred orientations (CPO) with their own macroscopically effective anisotropic viscosities that have proven difficult to estimate from the microscopic anisotropies of individual olivine crystals. Here we present a simple method to derive anisotropic viscosity parameters directly from the CPO mean orientation tensors. To calibrate the method, we created a large database of textures likely to occur in geodynamic simulations. We tested our method within numerical simulations of simple shear with both constant and varying shear directions. Finally, we integrated our method into the geodynamic code ASPECT, where...

Crustal-Scale Signatures of Steady-State Thermal Inheritance: Insights from the South China Sea

Wed, 25 Feb 2026 00:00:00 +0000

Long-lived lateral variations in radiogenic heat production create persistent thermal heterogeneities that shape continental lithosphere over geological timescales. We introduce a steady-state concept of thermal inheritance, linking these variations to crustal-scale strain localization and tectonic architecture.
Using numerical models, we explore both crustal- and lithospheric-scale consequences of heterogeneous heat production. A key finding is that lateral variations in heat production leave a distinct crustal-scale tectonic signature, controlling patterns of strain localization. The South China Sea serves as a proof-of-concept: the segmented, oblique extension observed there aligns with zones of mechanically weaker crust, reflecting the underlying inherited thermal heterogeneity.
These results highlight that crustal-scale tectonic features can emerge from steady-state thermal conditions, independently of transient anomalies. They provide a quantitative framework linking...

Lithospheric Mantle Density Anomalies Determined From Lithosphere Thickness and Dynamic Topography

Mon, 12 Jan 2026 00:00:00 +0000

Chemical buoyancy within the lithosphere may be prevalent in certain depth regions. To constrain those depths, we follow an approach similar to Wang et al. (2023) and plot the difference between residual topography—where only crustal isostatic topography has been removed—and dynamic topography—where only sub-lithospheric density anomalies are considered—against lithosphere thickness. In theory, this difference should be caused by density anomalies in the lithosphere, and the slope of the fitting line versus lithosphere thickness should hence indicate depth-dependent density anomalies in the lithosphere. When computing dynamic topography, lithosphere thickness and density anomalies outside the continental lithosphere are derived from tomography. Within the continental lithosphere, density anomalies are set to a reference value, for which we use either the global mean, or the depth-dependent mean values below mid-ocean ridges. With densities in the continental lithosphere...