U-Pb zircon, monazite and xenotime geochronology of cordierite-anthophyllite and felsic volcanic rocks in Orijärvi, southern Finland

Abstract

<p>We sampled one felsic volcanic rock from the lower part of the Kisko formation and two cordierite-anthophyllite rocks from Orijärvi and Iilijärvi for U-Pb dating. The felsic volcanic rock yield a zircon 207Pb/206Pb weighted average age of ~1.89 Ga. The oldest zircons from the Orijärvi cordierite-anthophyllite rock give a weighted average age of ~1.89 Ga. The monazite from the same sample yield a concordia age of ~1.80 Ga and the xenotime yield a concordia age of ~1.82 Ga. The Iilijärvi cordierite-anthophyllite rock gives a monazite concordia age of ~1.82 Ga. This implies that two metamorphic pulses are recorded in the samples.<br /></p>