The U–Pb age of the Finse batholith, a composite bimodal Sveconorwegian intrusion

The Sveconorwegian autochthonous basement in the Finse area, South Norway, comprises a c. 900 km2 bimodal batholith, dominated by K-feldspar megacrystic granite. The granite is locally intermingling with gabbroic rocks, and cut by different generations of pegmatite and aplite dykes. Zircon U–Pb geochronological data obtained by ID–TIMS demonstrate that granite, granodiorite and gabbro are coeval, as they define a common upper intercept age of 985.6 ± 1.6 Ma, dating emplacement of the batholith. Titanite is variously disturbed by later Sveconorwegian events. Pegmatites cross-cutting all structures yield zircon and titanite ages of 976 ± 8 Ma, 939 ± 2, and possibly 958 ± 2 Ma, reflecting the latest stages of the evolution of the batholith. The Finse batholith is one of the earliest members of the widespread ferroan hornblende-biotite-granitoid (HBG) suite, in the western part of the Sveconorwegian orogen.

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