Seven out of nine samples of metagabbro and monzonite from the Øksfjord peninsula, West Finnmark, give a Rlr-Sr age of 829 ± 18 Ma (2o, MSWD = 1.4), with an initial 87Sr/8?r ratio of 0.70272 ± 4 (2o). This age is interpreted as the age of intrusion, the source being a depleted mantle reservoir. These results, together with other recent and previous radiometric dates from the area, imply that the period of magmatic activity in the Seiland Igneous Province lasted for at )east 300 Ma.
A Precambrian age for an early gabbromonzonitic intrusive on the Øksfjord peninsula, Seiland Igneous Province, northern Norway
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