SUDBURY IMPACT CRATER SULFIDES
The Sudbury Complex (Sudbury Basin) in southeastern
Canada has intrigued geologists for decades, and not just due to the tremendous
economic value of the areaÕs mineral deposits.
Sudbury is one of the largest preserved impact
structures on Earth. The impact occurred ~1.85 billion years ago, during
the late Paleoproterozoic. The Sudbury Impact
Structure is no longer circular or subcircular in shape, however - it's
been compessed into a stretched-egg shape from an ancient continental collision
event.
Chalcopyrite (CuFeS2) (field of view ~4.5 cm) from the Sudbury Impact
Crater in Ontario, Canada. The specimen really does look like this -
better, in fact. This gorgeous rock comes from a massive sulfide vein
hosted in Neoarchean-aged Levack Gneiss (2.64 to 2.71 billion years) from the
Coleman MineÕs 153 orebody (North Range, northwest of Sudbury, southeastern
Ontario, Canada). Sulfide mineralization likely occurred during or very
soon after the Sudbury impact event at 1.85 billion years (Paleoproterozoic).
Tarnished chalcopyrite (CuFeS2) (2.5 cm tall) from the Sudbury Impact Crater in
Ontario, Canada. This rock comes
from a massive sulfide vein intruded within the Levack Gneiss Complex
(Neoarchean - 2.64 to 2.71 billion years), which forms the northwestern
"footwall" of the Sudbury Impact Crater. Sulfide mineralization
likely occurred during or very soon after the Sudbury impact event at 1.85
billion years (Paleoproterozoic).
Locality:
Coleman Mine (apparently derived from the 153 Orebody, at about 1290-1460
meters depth), North Range, northwest of the city of Sudbuy, southeastern
Ontario, southeastern Canada.
Pentlandite (Ni,Fe)9S8) in
pyrrhotite (Fe1-xS)
(above & below; 3.4 cm across) from the Sudbury Impact Structure in
Ontario, Canada. Sulfide
mineralization likely occurred during or very soon after the Sudbury impact
event at 1.85 billion years (Paleoproterozoic).
Bright patches at left & top-center right = pentlandite
Brassy gray-brown areas = pyrrhotite
Black
= magnetite
Locality:
South Mine, near Sudbury, southeastern Ontario, southeastern Canada.
Pentlandite (Ni,Fe)9S8) in
pyrrhotite (Fe1-xS)
(above & below; 8.35 cm across) from the Sudbury Impact Structure in
Ontario, Canada.
Bright gold-colored patches = pentlandite
Brassy gray-brown areas = pyrrhotite
Dark grayish to black patches & network = magnetite
Geologic Context & Age: massive sulfide, 800 Orebody at contact of the
Copper Cliff offset dike (quartz diorite) & McKim Formation deltaic
metapelites (upper Elliot Group, lower Huronian Supergroup, lower
Paleoproterozoic, 2.45 b.y.), sulfide mineralization was early post-Sudbury
Impact, 1.85 b.y.
Locality:
800 Orebody, South Mine (Copper Cliff South Mine), near Sudbury, southeastern
Ontario, southeastern Canada.
