| Computer Code: |
BDLA |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Arundian Substage (CJ)
— Asbian Substage (CR) |
| Lithological Description: |
The Boyd's Burn Lava Member consists of plagioclase-macrophyric trachybasalt lavas (hawaiite of 'Markle' type). These show a marked variation in the concentration and size of the plagioclase phenocrysts both between and within flows. There are basaltic lapilli-tuffs between the lavas. In the Goat Burn [NS 637 793], a compound flow with three 'flow units' is almost 15 m in thickness. The lavas have a rather slaggy and decomposed nature suggesting that they lie close to their eruptive source, considered to be the Waterhead Centre ('Waterhead Central Volcanic Complex') (Craig, 1980). |
| Definition of Lower Boundary: |
The basal plagioclase-macrophyric hawaiite lava of the member is conformable or disconformable on underlying basaltic-trachyandesite (mugearite) of the Lower Lecket Hill Lava Member. |
| Definition of Upper Boundary: |
The Boyd's Burn Lava Member is overlain conformably or disconformably by the Upper Lecket Hill Lava Member. The lithological change is mostly to more-felsic lavas, including two basal basaltic-trachyandesite (mugearite) lavas, trachybasalt (hawaiite), and trachyte, but also including plagioclase-microphyric basalt to trachybasalt (of 'Jedburgh' type). |
| Thickness: |
37 to 50 m |
| Geographical Limits: |
The member is restricted to the Campsie Block and has a limited geographical extent, (reflecting the proximal character of the lava flows) in the eastern Campsie Fells and westernmost Kilsyth HIlls, north of Glasgow. |
| Parent Unit: |
Clyde Plateau Volcanic Formation (CPV)
|
| Previous Name(s): |
Boyd's Burn Lavas [Obsolete Name and Code: Use BDLA]
(-4448)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Area |
The eastern Campsie Fells, and westernmost Kilsyth HIlls, north of Glasgow Forsyth et al., 1996, after Craig, 1980. |
| Reference Section |
Boyd's Burn, westernmost Kilsyth Hills, north of Galsgow. The maxium thickness of the member, about 50 m, is developed here, where at least four lavas with proximal-facies characteristics occur and tuffaceous deposits between the lavas are well developed. Craig, 1980. |
| Reference(s): |
| Dean, M T, Browne, M A E, Waters, C N, and Powell, J H. 2011. A lithostratigraphical framework for the Carboniferous successions of northern Great Britain (onshore). British Geological Survey Research Report RR/10/007. 165 pp. |
| Craig, P M. 1980. The Volcanic Geology of the Campsie Fells area, Stirlingshire. Unpublished Ph.D thesis, University of Lancaster. |
| Forsyth, I H, Hall, I H S, and McMillan, A A. 1996. Geology of the Airdrie district. Memoir of the British Geological Survey, Sheet 31W (Scotland). |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
S031
|
