| Computer Code: |
THKD |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Caradoc Series (O4)
— Caradoc Series (O4) |
| Lithological Description: |
A garnet-bearing, alkali feldspar-quartz-plagioclase-phyric microgranite. Age: 451.0 +/- 1.1 (2-sigma) Ma (U-Pb, zircon), Millward, D and Evans, J A, 2003. |
| Definition of Lower Boundary: |
Not defined. |
| Definition of Upper Boundary: |
Not defined. |
| Thickness: |
A laccolith 0.5 to 1km thick and with an area of about 12 sq. km intruded into the Skiddaw Group and lowermost part of the Borrowdale Volcanic Group. |
| Geographical Limits: |
Low Rigg [NY 305 230],Threlkeld Knotts [NY 328 238], around White Pike [NY 339 229] and in Bramcrag Quarry, east of Keswick,Cumbria. |
| Parent Unit: |
Lake District Ordovician Felsic Plutonic Suite (LDFP)
|
| Previous Name(s): |
Threlkeld Microgranite [Obsolete Name and Code: Use THKD]
(-3723)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Section |
Bramcrag Quarry, east of Keswick Cumbria. Wadge et al.(1974), Loughlin (1999). |
| Reference(s): |
| Loughlin, S C.1999. Bramcrag Quarry in Stephenson, D, Bevins, R E, Millward D, Highton, A J, Parsons I, Stone P, and Wadsworth W J. Caledonian igneous rocks of the British Isles. (Peterborough: Joint Nature Conservation Committee.) >References cited contain other important subsidiary references. |
| Wadge A J, Harding, R R, and Darbyshire, D P F. 1974.The Rb-Sr age and field relations of the Threlkeld Microgranite.Proceedings of the Yorkshire Geological Society, Vol.40, p.211-222.>References cited contain other important subsidiary references. |
| Woodhall, D G. 2000. Geology of the Keswick district. British Geological Survey Sheet Description, England and Wales, Sheet 29. |
| Millward, D, and Evans, J A. 2003. U-Pb chronology and duration of Upper Ordovician magmatism in the English Lake District. Journal of the Geological Society of London, Vol. 160, 773-781. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E029
|
