Burncrooks Volcaniclastic Member

Burncrooks Volcaniclastic Member (BCV), Kilpatrick Hills, Carboniferous, Midland Valley of Scotland

The Burncrooks Volcaniclastic Member is part of the Clyde Plateau Volcanic Formation.

Name

Previously known as the Burncrooks Pyroclastic Member (Hall et al., 1998).

Lithology

Volcaniclastic sedimentary rocks, some lacustrine, tuff and agglomerate. Pyroclastic rocks include cones which in some places coalesce. Lacustrine sedimentary rocks in the form of mudstone containing fish scales, overlying a discontinuous coal seam, are exposed south of Rigangower (NS 438 757).

Stratotype

The member crops out around Fyn Loch (NS 460 772) and Lily Loch (NS 473 780) where it is 10–20 m thick and consists mainly of tuff and volcaniclastic sedimentary rocks. A reference section is the Loch Humphrey Borehole (BGS Registration Number NS47NE/1) (NS 4582 7555) that penetrates the entire 70 m thickness of the Burncrooks Volcaniclastic Member, which is overlain by the Auchineden Lava Member and underlain by sedimentary rocks of the Clyde Sandstone Formation. In the borehole, the member mainly consists of tuff and lapilli-tuff, with a few thin lavas and sandstone beds. A full geological description of the core is available.

Lower and upper boundaries

The Burncrooks Volcaniclastic Member is underlain by the sedimentary rocks of the Clyde Sandstone Formation (Inverclyde Group).

The member is overlain by the lavas of the Auchineden Lava Member and Saughen Braes Lava Member.

Thickness

Between 0 and 80 m, very variable, thins to the north-east and south.

Distribution and regional correlation

The Burncrooks Volcaniclastic Member crops out along the north-western and western margins of the Kilpatrick Hills lava block. It stretches from north-east of Bowling (NS 455 739) to Burncrooks Reservoir (NS 482 796) with more isolated patches along the northern margin of the faulted block as far east as (NS 5500 8000).

Age

Mid Visean (Arundian to Asbian).