Bulletin 91:
Bedrock Geology of the Germansen Landing
- Manson Creek
Area, British Columbia
By F. Ferri and D.M. Melville, 1994
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| The Germansen Landing-Manson Creek area, which is located
within the southern Omineca Mountains of north-central British Columbia, is
the subject of Bulletin 91. This region straddles the Intermontane-Omineca
Belt boundary and encompasses rocks from five tectonostratigraphic terranes
and subterranes. These are: North American siliciclastics and carbonates of
the Cassiar Terrane, represented by the Upper Proterozoic Ingenika Group
through to the Devonian to Permian Big Creek group; pericratonic clastics of
the Kootenay Terrane, comprised of the Upper Proterozoic to Paleozoic(?)
Boulder Creek group; the oceanic Slide Mountain Terrane, which is made up of
deep water argillites, cherts and basalts of the Mississippian to Permian
Nina Creek group, arc volcanics and sediments of the Triassic to Jurassic(?)
Takla Group of the Quesnel Terrane; and the Harper Ranch Subterrane,
represented by Mississippian (?) to Permian arc volcanics and sediments of
the Lay Range assemblage. These rocks were
polydeformed and strongly metamorphosed beginning in the Mesozoic as a
result of collision and obduction of exotic terranes from the west. Middle
Jurassic, northeast-verging D1 deformation was accompanied by regional
metamorphism, which reached sillimanite grade within the Wolverine
Metamorphic Complex. Rocks of the Nina Creek group were imbricated and
emplaced on top of North American rocks during this time period. Middle to
Late (?) Jurassic D2 deformation refolded these rocks into upright to
northeast and southwest (?) -verging structures. D3 deformation broadly
warped and uplifted these rocks during the Early to Middle Cretaceous. Late
Cretaceous to Tertiary right-lateral movement along the Manson fault zone
was accompanied by dip-slip motion on the brittle-ductile,
southwest-side-down Wolverine fault zone in response to uplift of
metamorphic rocks within the Wolverine Complex. Rapid uplift of these rocks
is recorded by early Tertiary K-Ar cooling dates. Rocks in the hangingwall
of the Wolverine fault zone cooled relatively early in the deformational
sequence (Middle Jurassic).
The map area contains a wide variety of mineral
occurrences that reflect the long and complex history recorded by these
rocks. The most abundant are polymetallic veins genetically related to the
Manson fault zone and spatially related to strongly altered ultramafic
bodies. Stratabound carbonate-hosted lead-zinc mineralization in the Otter
Lakes group is locally important. Placer gold was mined in the district
dating back to the late 1800s. Carbonatites form sill-like bodies along the
Wolverine fault zone that locally have anomalous niobium values, and younger
alkalic intrusives have anomalous REE concentrations. |
Last updated
June 08, 2006 |
