KITCHI FORMATION
The Kitchi Formation is a
very thick, metamorphosed, heterolithic volcanic unit of Neoarchean age in the
Negaunee-Ispheming area of Michigan's UP. It consists of a succession of
basalt lava flows, volcanic breccias, and volcanic tuffs (all
metamorphosed). The photos below show a spectacular volcanic metabreccia
outcrop on the southern shores of Deer Lake, northwest of Ishpeming (see
map).
The outcrop is a glacially
smoothed & striated low knob. The rocks are part of the middle Kitchi
Formation and consist of volcanic metabreccias of andesitic to dacitic
composition. Despite metamorphism, the original clasts are very well
defined in terms of shape, color, and composition. The unit has been
inferred to represent a subaqueous volcanic debris flow.
Volcanic metabreccia in the mid-Kitchi Formation
(Neoarchean) - Deer Lake South outcrop.
Volcanic metabreccia in the mid-Kitchi Formation
(Neoarchean) - Deer Lake South outcrop.
Volcanic metabreccia in the mid-Kitchi Formation
(Neoarchean) - Deer Lake South outcrop.
Volcanic metabreccia in the mid-Kitchi Formation
(Neoarchean) - Deer Lake South outcrop.
Volcanic metabreccia in the mid-Kitchi Formation
(Neoarchean) - Deer Lake South outcrop.
Some info. from:
Bornhorst & Johnson
(1993). Geology of volcanic rocks in the south half of the Ishpeming Greenstone
Belt, Michigan. USGS Bulletin 1904-P. 13 pp.