The geology and geochemistry of a Robinson Creek gold ocurrence, north of Amisk Lake, Saskatchewan
Date
1986
Authors
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ORCID
Type
Degree Level
Masters
Abstract
The Robinson Creek Gold Occurrences, situated
approximately, 12 kilometers southwest of Flin Flon,
Manitoba, are of the typical quartz vein type. Mineralized
quartz veins are contained within shear zones, hosted
within rocks which may represent structurally deformed,
metamorphosed and chemically altered, mafic volcanic flows
and or related pyroclastic rocks of the Amisk Group
volcanics. Metamorphosed intermediate to felsic volcanic
rocks (dacite to rhyolite), also belonging to the Amisk
Group, are found stratigraphically above the mafic
volcanics, and may represent former volcanic flows and
related pyroclastic rocks. These rocks are intruded by two
varieties of porphyritic dacite to rhyodacite of
contrasting age. The Amisk volcanic rocks are overlain by
highly deformed conglomerates and rare sub-arkosic
sandstone of the Missi Group sediments. Clasts in the
conglomerate were probably derived from the underlying
Amisk volcanics (Stauffer and Mukherjee, 1971).
The Amisk volcanics probably represent a transition
from tholeiitic to calc- alkaline chemical affinities (Fox,
1976, Walker and Watters, 1982) and perhaps from an ocean
floor to an island arc setting (Stauffer, 1974). However,
all of the rocks in the area have been affected by several
phases of deformation and are metamorphosed to greenschist
to lower amphibolite grade. Chemical alteration of the
rocks has been enhanced be penetrative deformation, most
noticeable in the Robinson Shear system which hosts the
gold.
The typical secondary assemblage is ferroan dolomite
(ankerite), quartz, chlorite, muscovite (sericite), pyrite
and locally tourmaline. Carbonate alteration (ankerite),
predates the introduction of the gold-bearing quartz veins
in the sheared mafic volcanics. Metasomatic alteration of
the mafic rocks associated with gold mineralization is
typified by an enrichment in Rb, Sr, and K and depletion in
Na, Ca, and variably Mg. Metasomatism is generally
associated with a volume increase in sheared rocks and a
volume reduction in rocks with minor penetrative
deformation.
The gold-bearing quartz veins are interpreted to be in
a dilatent zone hosted within two shear zones located near
the hinge of a tightly closed anticline with a steeply
dipping axial surface.
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Degree
Master of Science (M.Sc.)
Department
Geological Sciences
Program
Geological Sciences