Publication Type:

Journal Article


Bulletin of Volcanology, Springer International [for the] International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI), Heidelberg, Germany, Volume 75, Number 3, p.1-14 (2013)




andesitic composition, basaltic composition, basalts, breccia, Canada, Canadian Shield, dikes, Flin Flon Belt, Flin Flon Manitoba, igneous rocks, intrusions, lava, Manitoba, massive deposits, massive sulfide deposits, North America, Paleoproterozoic, pillow lava, pillow structure, Precambrian, proterozoic, upper Precambrian, volcanic rocks, volcaniclastics, Western Canada


The Paleoproterozic 1920 unit occurs at the base of the Hidden formation, overlying greater than 90 million tons of volcanogenic massive sulfide deposits at Flin Flon, Manitoba, Canada. The 1920 unit is a laterally discontinuous, Fe-Ti-P-rich basaltic andesite (Fe (sub 2) O (sub 3) 12 wt.%, TiO (sub 2) 1.1 wt.% and P (sub 2) O (sub 5) 0.30 wt.%), consisting of massive, pillowed and in situ brecciated basaltic andesite. The 1920 unit is characterised by facies, textures and structures similar to those associated with subaqueous basaltic lavas. However, the presence of blocky and fluidal peperite along the upper contact, and lens-shaped inclusions of tuff within and along its basal contact, as well as the discordancy of the upper contact suggest that the predominantly massive, basaltic andesite was emplaced as a high-level, synvolcanic sill into wet, unconsolidated volcaniclastic deposits. The presence of a breccia containing clasts of the 1920 unit within the package of volcaniclastic rocks overlying the 1920 unit, and a pillowed facies within the 1920 unit, suggest that, locally, the 1920 unit breached the seafloor. An abundance of synvolcanic dikes within the footwall to the 1920 unit, including the presence of a basaltic andesite dike that merges into the 1920 unit, indicates the possible location of the feeder for the 1920 unit in the northwestern portion of the area. Copyright 2013 Springer-Verlag Berlin Heidelberg


GeoRef, Copyright 2018, American Geological Institute.<br/>2013-068991<br/>Hidden Formation