Within the Flin Flon Basin, Precambrian meta-sandstones and conglomerates belonging to the Missi Group have been complexly deformed as a result of three periods of deformation. The first two periods (P1 and P2) involved folding but no apparent faulting, the last (P3) involved both folding and faulting. Progressive metamorphism (M2), within the greenschist facies, occurred during the second phase (P2) and aided in the formation of a pronounced axial-plane foliation (S2). Small-scale folding and retrograde metamorphism (M3) occurred along faults formed during the last phase (P3).The faults in this area all appear to be high angle, oblique-slip reverse faults and can be interpreted as having formed during a single orogenic event (P3) although there is sequence in their initiation. The net-slip directions of different faults are approximately the same, and plunge moderately to the southeast, with either the east or south side upthrown, depending on the attitude of the fault.

The Amisk Group (Aphebian?) near Flin Flon, Manitoba, consists dominantly of andesitic lava flows and pyroclastic rocks, with minor basalt, dacite, rhyolite, and epiclastic rocks. These have undergone regional metamorphism ranging from chlorite to garnet zone, and locally have been sheared intensely.Major element chemical analyses indicate that intensely sheared Amisk rocks near the Flin Flon and Schist Lake Cu–Zn ore bodies have undergone considerable metasomatism. The unsheared, regionally metamorphosed rocks have undergone significantly less metasomatism, and the compositions of the least-altered of these suggest an island arc tholeiite chemical affinity.The lithology, primary structures, and major-element compositions of lavas within the Amisk Group suggest deposition may have been in an island arc environment.

Whole rock Rb/Sr age dating near Flin Flon, Manitoba, yields isochrons of 1775 89 m.y. for the Amisk Group (mainly volcanic rocks), and 1805 + 14 m.y. for the granodioritic Annabel Lake Pluton which intrudes the Amisk. These are considered t o be emplacement ages (within their errorlimits).A tentative interpretation of the Hudsonian Orogeny in this area is derived by fitting the Rb/Sr ages and previously published K/Ar ages to the sequence of events as determined from detailed structural studies. According to this interpretation, Amisk volcanism began approximately 1865 m.y. ago, and the Hudsonian Orogeny ended approximately 1800 m.y. ago. --Des mesures radiometriques au rubidium sur les roches totales de la rCgion de Flin Flon (Manitoba) ont donne des isochrones de 1775 + 8.9 m.a. pour le Groupe d'Amisk (form6 surtout de roches volcaniques) et 1805 + 14 m.a. pour le pluton granodioritique du Lac Annabel, intrusif dans le Groupe d'Amisk. Compte tenu des limites d'erreur, ces dges sont des dges de mise en place.On peut tenter une interpretation de I'orogenkse hudsonienne dans cette rCgion en mettant en parallkle les dges Rb/Sr et les dges K/Ar d6jB publiCs avec la skquence d'evknenements obtenue d'aprks les Ctudes structurales de dCtail. Ainsi, le volcanisme amiskien aurait commencC vers -1865 m.a. et l'orogenkse hudsonienne se serait terminee il y a 1800 m.a.

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