‘Older’ granites as time-markers in Dalradian evolution

• DOI: 10.1144/gsjgs.132.6.0677
• Publication Date: 2007-12-20T22:39:02Z
• Authors: H. J. BRADBURY; R. A. SMITH; A. L. HARRIS
• Keywords: Dalradian

The ‘older’ granites of Perthshire were emplaced in the Dalradian between second and third deformation episodes a Caledonian D1–D4 sequence. Pankhurst & Pidgeon (1976) have furnished zircon U-Pb Rb/Sr whole-rock age (514 +6/–7 Ma) for emplacement Ben Vuirich granite which provides minimum D2 event. A somewhat younger isochron (491 ± 15 obtained from Dunfallandy Hill may date D3. Migmatisation occurred D2–D3 interval is, by inference, also dated. Dl D2, deform Arenig rocks Southern Highlands Group are pre-514 Ma events implying time base Ordovician.