Mugdock Lava Member

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Mugdock Lava Member (MGLA), Kilpatrick Hills, Carboniferous, Midland Valley of Scotland[edit]

The Mugdock Lava Member is part of the Clyde Plateau Volcanic Formation.

Name[edit]

Previously named the Mugdock Lavas (Hall et al., 1998)[1].

Lithology[edit]

Predominantly plagioclase-macrophyric basalts (‘Markle’ type). Near Devil’s Craig Dam (NS 560 782) a few lavas have abundant feldspar phenocrysts of about 5 mm and some up to 2 cm in length. Near Craigend Castle (NS 548 777) a thin olivine-clinopyroxene-macrophyric basalt (‘Craiglockhart’ type) occurs and in the western part of the Kilpatrick Hills, mugearite lavas are present.

Stratotype[edit]

The Mugdock Lava Member is well exposed in its type area between Mugdock Loch (NS 554 773) and Devil’s Craig Dam (NS 560 782).

Lower and upper boundaries[edit]

The Mugdock Lava Member overlies the more-mafic olivine-microphyric basalts (‘Dalmeny’ type), olivine-clinopyroxene-plagioclase-macrophyric basalts (‘Dunsapie’ type) and olivine-clinopyroxene-macrophyric basalts (‘Craiglockhart’ type) of the underlying Cochno Lava Member.

The Mugdock Lava Member is overlain by the olivine-microphyric basalts (‘Dalmeny’ type) of the Tambowie Lava Member in the south of the Kilpatrick Hills. To the north, the Tambowie Lava Member is absent and the Mugdock Lava Member is directly overlain by the sedimentary rocks of the Lawmuir Formation (Strathclyde Group).

Thickness[edit]

About 200 m thick in the north-east Kilpatrick Hills, thinning to about 100 m in the south-west of that area.

Distribution and regional correlation[edit]

Kilpatrick Hills: The Mugdock Lava Member is present in the south of the area, between Old Kilpatrick (NS 465 730), where it is continuous with the upper part of the Strathgryfe Lava Member of the Renfrewshire Hills lava block south of the River Clyde, and the area around Mugdock (NS 56 77). The lavas might have been derived from the Waterhead Volcano-complex in the Campsie Fells lava block.

Age[edit]

Mid Visean (Arundian to Asbian).

References[edit]

  1. Hall, I H S, Browne, M A E, and Forsyth, I H. 1998. Geology of the Glasgow district. Memoir of the British Geological Survey, Sheet 30E (Scotland)