Abstract

U-Pb analyses of zircons from the Ennerdale granitic intrusion and Eskdale Granite (English Lake District) give ages of 452 ± 4 Ma and 450 ± 3 Ma respectively. These data confirm the sub-volcanic association of these intrusions, and show that previously published Rb–Sr whole-rock and K–Ar mineral ages do not correspond to the emplacement and cooling of these igneous bodies. The new ages show that only two phases of acid magmatism can now be linked to the exposed parts of the Lake District batholith. The Caradoc (late Ordovician) phase was caused by the subductionrelated processes which gave rise to volcanism, and was followed by a separate early Devonian phase of granite emplacement.

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