Computer Code: |
AMOG |
Preferred Map Code: |
notEntered |
Status Code: |
Index Level |
Age range: |
Paleoproterozoic Era (AL)
— Paleoproterozoic Era (AL) |
Lithological Description: |
[Obsolete: use SMOG] Comprises the Fe-rich members of the Scourie Dyke Swarm. The dykes of the Subswarm occur within the Lewisian Gneiss Complex in the Assynt region, and they typically have a broadly east-west trend. They have the primary mineralogy olivine - clinopyroxene - orthopyroxene - plagioclase - kaersutite - biotite - Fe-Ti oxide, although most have been subjected to amphibolite-facies metamorphism and thus many of the original minerals have been replaced. |
Definition of Lower Boundary: |
Contacts are cross-cutting, and have been modified by subsequent metamorphism. |
Definition of Upper Boundary: |
N/A. |
Thickness: |
From about 50 cm to 50 m thick. |
Geographical Limits: |
The dykes are part of the Lewisian Gneiss Complex and only occur within it. They have only been mapped as a separate subswarm in the Assynt area (between Loch Laxford in the north and Loch Lurgainn in the south). |
Parent Unit: |
none recorded or not applicable
|
Previous Name(s): |
none recorded or not applicable
|
Alternative Name(s): |
none recorded or not applicable
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Stratotypes: |
Type Area |
The dykes of the Subswarm occur in the Lewisian Gneiss Complex of Assynt. The most well-studied examples are at Loch Sionascaig [NC 136 145]. Tarney, 1973; Tarney & Weaver, 1987. |
Reference(s): |
Weaver, B L and Tarney, J. 1981. The Scourie Dyke Suite: Petrogenesis and Geotechnical Nature of the Proterozoic Sub-Continental Mantle. Contributions to Mineralogy and Petrology, Vol.78, 175-188. |
Tarney, J. 1973. The Scourie Dyke Suite and the nature of the Inverian event in Assynt. 105-117 in Park, R G and Tarney, J (editors), The Early Precambrian of Scotland and related rocks of Greenland. [University of Keele.] |
Tarney, J. and Weaver, B L. 1987. Mineralogy, petrology and geochemistry of the Scourie dykes: petrogenesis and crystallization processes in dykes intruded at depth. p. 217-233 in Evolution of the Lewisian and Comparable Precambrian High Grade Terrains. Park, R.G. and Tarney, J. (eds.) Geological Society Special Publication No. 27. |
1:50K maps on which the lithostratigraphical unit is found, and map code used: |
S101
S102
S107
S108
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