Beltedrift

Beltedrift is a proposed geodynamic concept describing the lateral movement of elongated crustal belts relative to neighboring belts, driven by mantle convection and contrasts in rheology within the lithosphere. The term emphasizes belt-scale motion rather than the movement of entire tectonic plates and is used to explore how intraplate deformation can accumulate along pre-existing shear zones.

Mechanisms include differential forces generated by mantle convection, slab pull, ridge push, and viscosity contrasts between belts. If belts differ in thickness, composition, or thermal state, they may drift laterally, rotate, or develop shear between boundaries. The process can operate at regional to crustal scales and may be episodic, linked to pulses of mantle flow or changes in subduction regimes.

Evidence for beltedrift is currently limited. Signatures would include systematic lateral offsets of geological features within a plate that cannot be easily accounted for by whole-plate motion or terrane accretion alone. In practice, most observed intra-plate deformation is explained by alternative mechanisms such as distributed strain, strike-slip faulting along shear zones, or accretionary processes. In numerical and analogue models, beltedrift can arise when belts have contrasting rheology and mechanically weak boundaries.

Status: beltedrift remains a debated, largely theoretical concept rather than a universally accepted mechanism in mainstream tectonics. It is encountered mainly in modeling studies and discussions of intraplate deformation. See also plate tectonics, lithospheric shear zones, mantle convection, intraplate deformation.