The Sudbury Structure consists of three major components: 1) the Sudbu
ry Basin; 2) the Sudbury Igneous Complex which surrounds the basin as
an elliptical collar; and 3) an outer zone of shatter-coned and intens
ely brecciated footwall rocks. Although the Sudbury Event which formed
the structure may be unique, the area has, in fact, been shaped by a
series of tectonic, magmatic and mineralization events which can be co
nsidered in terms of two Wilson cycles of continental extension and cl
osure. The first cycle, from 2500 to 1700 Ma, included the following e
vents: doming (uplift of Levack Gneiss Complex); NE-SW extension (Mata
chewan dikes); N-S to NW-SE rifting (faults, mafic intrusions, sedimen
tation, and Ni-Cu-PGE and U mineralization); NW-SE extension (Nipissin
g diabase, and Ni-Cu-PGE, Ag, Co mineralization); and NW-SE and NE-SW
closure (Penokean Orogeny, 1900 to 1700 Ma) with superimposed meteorit
e impact (1850 Ma, Ni-Cu-PGE, Zn-Cu-Pb deposits). The second cycle, fr
om 1700 to 1000 Ma, included: N-S extension (alkali metasomatism, Au);
N-S extension (hornblende diabase dikes along the Murray fault set);
NNE-SSW extension (olivine diabase dikes); NE-SW extension (Fecunis La
ke fault set); and NW-SE closure (Grenvillian Orogeny). The rich and d
iverse Ni-Cu-PGE and subordinate Zn-Pb-Cu and Au mineralization of the
Sudbury region is related to endogenic and impact-triggered crustal e
xtension and magmatism. The Sudbury Structure apparently was the site
of a triple junction or hot-spot. The Sudbury ores, although located w
ithin an impact structure, are analogous in terms of age and tectonic
setting to Ni-Cu-PGE and Zn-Pb-Cu ores elsewhere in the world. Meteori
te impact accentuated on-going ore forming processes and magmatism at
Sudbury. (C) 1997 Canadian Institute of Mining, Metallurgy and Petrole
um.