Acritarchs from the Ordovician of the Oslo Region, Norway CRISTIANA RIBECAI, DAVID L. BRUTON & MARCO TONGIORGI

Ribecai, C., Bruton, D. L. & Tongiorgi, M. Acritarchs from the Ordovician of the Oslo Region, Norway. Norsk Geologisk Tidsskrift, Vol. 80, pp. 251-258. Oslo 1999. ISSN 0029-196X. Ordovician (Tremadoc-Early Llanvirn age) acritarchs are recorded for the first time from five samples in the Asker-Røyken area, south of the Oslo Region, Norway. Two samples from the Nes-Hamar district in the north were barren. Permian contact metamorphic temperatures of the sampled area are in excess of 300°C and are consistent with the conodont Colour Alteration Index (CAI). This study confirms that suggested previous temperature thresholds (