Geoscience Reference
In-Depth Information
Fig. 14.1
Location map of the Cerro Colorado Mine in northern Chile. Courtesy of Compañía Minera Cerro Colorado S.A.
volcanic ignimibrite (ash-flow tuff). The total thickness of
un-mineralized cover, including conglomerate, ignimbrite
and colluvium deposits, varies from 30 m over the east half
of the East deposit to more than 100 m over the West depos-
it, with an average thickness of post-mineral cover of about
60 m.
The andesites consist of lithic, lapilli tuff, porphyritic
flows and coarse, flow breccias and agglomerates. Volca-
nic rocks dip to the south at a low angle. Quartz monzonite,
quartz-monzonite microbreccia and tonalite porphyry form
complex bodies intruding andesites in the West and East de-
posits. Above an elevation of about 2,600 m, quartz mon-
zonite and quartz-monzonite microbreccia are present as
large east-west trending bodies in the West deposit and as
northeast-trending shapes in the East deposit. Breccia bodies
coalesce below an elevation of 2,550 m, forming a northeast-
trending body extending from the western edge of the West
deposit to the northeast end of the East Deposit, surrounded
by numerous apophyses of tonalite porphyry. The number
and extent of tonalite porphyry intrusives increases with
depth, eventually merging below an elevation of 2,450 m
to form a large stock surrounded by smaller apophyses of
porphyry and intermixed with bodies of quartz-monzonite
microbreccia.
