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(c) layered mafic bodies, as at Great Lakes Nickel Company
property in Pardee Township
(d) dykes and associated stocks cutting all Helikian and
Aphebian rocks.
The Coldwell syenite complex near Marathon is an undersaturated
laccolith, similar in age to the other Helikian intrusive rocks
(Pairbairn et al, 1959).
STRUCTURE
Structural deformation is limited to block faulting and regional
tilting, imposed during and after Keweenawan intrusive and volcanic
periods. Two parallel major fracture or fault zones bound the block
of Aphebian and Paleohelikian rocks exposed in the northwestern Lake
Superior region. The most northerly of these is a steeply dipping
fracture zone, five miles in width extending from west of Whitefish
Lake to east of Pass Lake. Dragfolding of sediments along faults
suggests slight uplift of the southern side. The northern boundary
is marked by a fracture zone which is occupied by the northeast—
trending dyke set. The block between these faults has been slightly
tilted, resulting .in a 3 to 5 degree dip of the sediments to the southeast.
ACKNOWLEDGEMENT
The authors wish to acknowledge the assistance of S. Spivak, who
compiled and drafted the figures.
S ELECT ED
REFERENCES
Baarghorn, D.S. &
Tyler, S.A., 1965;
Butuzova, G.Y., 1966;
DuBois, P.M., 1962
Micro—organisms from the Gunf lint chert:
Science, v. 147, p.563—577.
Iron ore sediments of the fumarole field
of Santorin volcano, their composition
and origin: (Zhelezorudngye osadki
fumarol 'ngo polya vulkana Santorin,
ikh sostav i genezis): Doklady Akad.
Nauk., S.S.SR., v.168, no.6, p.1400—1402.
Paleomagnetism and correlation of
Keweenawan rocks: Geol. Survey, Canada,
Bull. 71.
Fairbairn, B,W.,
Age -investigation of syenites from
Bullwinkel, 113., Coldwell, Ontario: Proc. Geol. Assoc.
Pinson, W.B., &
Can., v.11, i'l4ll44.
Burley, P.M., 1959;