Zircon dating of the basalt and felsic dyke in Haveri, SW Finland

Abstract

<p>The E-MORB type Haveri basalt differs from the volcanic arc type rocks in the Tampere<br>belt showing no subduction signature. It is considered to have formed in a marginal<br>basin prior to the volcanic arc. We present here zircon U-Pb dating on two samples. The<br>basalt and the felsic dyke yielded 207Pb/206Pb ages of 1902 ± 5 Ma and 1891 ± 2 Ma,<br>respectively, interpreted as crystallisation ages. The basalt also contains older 1.98 Ga<br>grains while the felsic dyke contains older 1.92 Ga, 1.94 Ga, 1.98 Ga and 2.0 Ga grains,<br>which are inferred as inherited. The age dating of E-MORB type basalts can be used to<br>identify the extensional episodes of the accretionary Svecofennian orogeny.<br></p>