Premilinary fission-track ages of fluorite mineralisation along frature zones, inner Trondheimsfjord, Central Norway
pp. 173-178

Fluorite mineralisation occurring along two major faults in coastal areas of inner Trondheimsfjord has been dated by the fission-track method. Fluorite from the Y stad Fault near Hylla gave ages of 57.4 ± 31.6 and 64.8 ± 22.6 Ma, while a sample from the Slipra Fault near Mosvik gave a date of 76.1 ± 41.2 Ma. Although caution must be exercised in view of the large error margins, the dating provides a minimum age of Late Cretaceous/Early Tertiary for this hydrothermal activity. It is suggested that the Huorite mineralisation developed in Late Cretaceous time shortly before a phase of rapid crustal uplift recorded in the Early Tertiary. The ages broadly coincide with that of a phase of alkaline magmatic activity, with late Huorite-calcite veining akin to that described here, reported from areas in East Greenland and which is considered to be related to the rifting and opening of the northern part of the North Atlantic Ocean