The Ala-Penikka PGE reefs in the Penikat layered intrusion, Northern Finland

Abstract

The PGE mineralized zones referred to as the Ala-Penikka PGE Reefs (AP I and AP II) are located about 250 m and 340 m above the base of megacyclic unit IV in the Penikat layered intrusion, both mineralizations being hosted by plagioclase-augitebronzite and narrow poikilitic plagioclase cumulates. A depression structure (pothole) about 300 m long and 100 m deep is encountered in the area of the AP I Reef, and it is in this structure that the AP I Reef, which is normally 30 cm thick, attains its maximum thickness of 20 m.