Mineral Inclusions in Zircon and Monazite Do Not Support the <scp>UHP</scp> History of the “Diamondiferous” Gneiss on the Island of Fjørtoft, Western Gneiss Region, Norway

ABSTRACT The Blåhø Nappe is an important allochthonous nappe in the Nordøyane ultrahigh‐pressure (UHP) domain, Western Gneiss Region, Norway. Since a few microdiamonds were seperated from a kyanite‐garnet gneiss of the Blåhø Nappe on the island of Fjørtoft, it has long been debated whether this nappe has experienced UHP metamorphism during the Caledonian orogeny. Here, a detailed study is reported on mineral inclusions in zircon and monazite of this “diamondiferous” gneiss. The inclusions are quartz, plagioclase, K‐feldspar, biotite, muscovite, amphibole, graphite, apatite, rutile, sillimanite, kyanite, calcite, and sulphides broadly in accordance with the matrix mineral assemblage. The absence of coesite, jadeite, or diamond as inclusions in zircon and monazite does not support a UHP history for the Blåhø Nappe. Therefore, the Blåhø Nappe is inferred to have experienced a tectonometamorphic evolution different from the Baltic basement that is assumed to be deeply subducted during the Caledonian orogeny.