The BGS Lexicon of Named Rock Units — Result Details

Tappetknowe Lava Member

Computer Code: TKLA Preferred Map Code: notEntered
Status Code: Full
Age range: Arundian Substage (CJ) — Asbian Substage (CR)
Lithological Description: The Tappetknowe Lava Member consists of of several lavas with a total thickness of approximately 40 metres. These include, near Tappetknowe [NS 750 815] microporphyritic basaltic-trachyandesite (mugearite), trachybasalt and rare plagioclase-macrophyric trachybasalt (of 'Markle' type). The rocks are intensely faulted and jointed and deeply weathered, with exposure limited to small crags. Craig (1980) has inferrred that the source of the lavas was nearby to the present outcrop.
Definition of Lower Boundary: The lower boundary is conformable or locally disconformable on the underlying Laird's Loup Lava Member which comprises plagioclase-macrophyric trachybasalt; it is taken as the incoming of microporphyritic lavas (basaltic-trachyandesite to trachybasalt).
Definition of Upper Boundary: The Tappetknowe Lava Member is overlain to the north-east of the Takmadoon Fault (Craig, 1980) by the Denny Muir Lava Member. The lithological change here is to massive, well-featured plagioclase-macrophyric basalt (of 'Markle' type), trachybasalt and rare basaltic trachyandesite (mugearite). To the south-east of the Tak-ma-doon Fault, the Tappetknowe Lava Member is overlain by the Kilsyth Hills Lava Member, and the lithological change is mainly to plagioclase-macrophyric basalts and trachybasalts (hawaiites of 'Markle' type).
Thickness: 40 m
Geographical Limits: The member is restricted to the southern part of the Campsie Block and specifically to the southern side of the central Kilsyth Hills, north-east of Glasgow.
Parent Unit: Clyde Plateau Volcanic Formation (CPV)
Previous Name(s): Tappetknowe Lavas (-1864)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Area  Central Kilsyth Hills, north of Glasgow Forsyth et al, 1996, after Craig, 1980 
Reference(s):
Forsyth, I H, Hall, I H S and McMillan, A A. 1996. Geology of the Aidrie district. Memoir of the British Geological Survey, Sheet 31W (Scotland). 
Craig, P.M. 1980 The Volcanic Geology of the Campsie Fells area, Stirlingshire. Unpublished PhD thesis, University of Lancaster. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
S031