Zircon age spectra from British Caledonian magmas are weighted according to surface area to investigate tectonic controls on magma generation and emplacement.

The area-weighted age spectra reveal an apparent absence of granitic magmatism during Iapetus subduction and a predominance of post-subduction magmas.

We review the apparent absence of subduction-related magmatism in the context of the poor preservation potential of such settings.

Magma generation was controlled by gravitationally driven kinematics following slab detachment and delamination caused by final subduction of the Iapetus Ocean. Magma emplacement was subsequently modulated by alternating episodes of transpression and transtension in the overlying continental lithosphere.

Area-weighted age spectra offer a valuable means of investigating magmatic-tectonic relations.