Geology Reference
In-Depth Information
Table 15.2 Archean potassic rocks (after Blichert-Toft et al. 1996)
Rock type
Geologic unit
Location
Age
(Ga)
The Superior
province,
Timiskaming group
Ontario
2.68
North America
shoshonites
Bijou point
Ontario
2.70
Oxford lake group
Manitoba
2.65
Opemisca group
Quebec
2.70
Rainy lake)
Quebec
7.70
Lamprophyre dikes
Abitibi greenstone belt,
OntarioAbitibi greenstone belt
Ontario
2.70
Kamiskotia
Montcalm suite
Ontario
2.70
-
Bristol township suite
Ontario
2.69
Roaring river complex
Ontario
2.70
Vermilion complex
Minnesota
2.70
Yollowknife greenstone belt
Northwest territories
2.70
Syenite and
nepheline
Poohbah lake
Ontario
2.70
Syenite stocks
Garrison stock
Ontario
2.68
Otto stock
Ontario
2.68
Murdock creek
Ontario
2.68
Herman lake
Ontario
2.67
Clericy, Aldermac, Nora lake
Quebee
2.68
Icarus and Linden Plutons
Ontario/ Minnesota
2.70
Lamprophyre dikes
Tanzania lamprophyre
dikesTanzania/ Zimbabwe
2.70
Lamproite dikes
Caroline
-
Amalie, across,
Skjoldungen, Southeast
Greenland
2.70
sound
Syenite and nephe-
line syenite stocks
Ruinnaesset, sphinxen,
blabaersaraent
Skjoldungen, Southeast
Greenland
2.70
particularly in the margin of the continents by the subduction processes, which was
not ef
cient during the Archaean because of the lack of old and thick lithosphere
during Archaean. This also might explain why rift-related magmas formed by
partial melting of metasomatized lithosphere could not have produced K-rich
magma during the ancient geological history of the earth.
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