NJG62-3-01
1982
Petrography and geochemistry of peralkaline, ultrapotassic syenite dykes of Middle Permian age, Sunnfjord, West Norway
62
3
147-159

Two peralkaline, ultrapotassic syenite dykes from Sunnfjord, West Norway yield Middle Permian K-Ar ages. The hydrothermally-altered dykes are composed of microcline, Si-rich and Al-poor phlogopite, an Al-deficient brown mica partly altered to saponite, eckermannite, celadonite, apatite, calcite, baryte and
the rare minerals dalyite and labuntsovite. The dykes are strongly enriched in K2O, Rb, Sr, Zr, Nb and LREE, and the ratios K2O/Na2O and K2O/Al2O3 are exceptionally high. They are geochemically similar to peralkaline lavas from Leucite Hills and may be related to comparable dykes in the Orkneys.

0029-196X
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