East Linton Lava Member

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East Linton Lava Member (ELLA), Carboniferous, Midland Valley of Scotland[edit]

East Linton Lava Member is part of the Garleton Hills Volcanic Formation

Name[edit]

Previously named the East Linton Member (see McAdam and Tulloch, 1985[1]).

Lithology[edit]

The East Linton Lava Member consists characteristically of macroporphyritic basalt and basanite (‘Craiglockhart’ type) and hawaiite (‘Dunsapie’ type), both with olivine and clinopyroxene (large augite) phenocrysts and the latter, also with plagioclase. Non-porphyric basaltic trachyandesites and a single leucite-bearing analcime trachybasalt (‘kulaite’) are also present. Beds of tuff and lapilli-tuff also occur in the succession. Flows are usually 5–15 m thick, the upper half of each being ‘slaggy’ and vesicular.

Stratotype[edit]

The type area is East Lothian (NT4600 6900 to 6000 8300) around North Berwick, East Linton, the Garleton Hills, and Stenton (see Davies et al., 1986, fig. 10[2]; McAdam and Tulloch, 1985, fig. 17[1]). Reference sections are provided by the IGS East Linton 2 Borehole (BGS Registration Number NT57NE/2) (NT 59664 77091) which provides a partial section through the member from 0 to about 48.8 m depth, and the Spilmersford Borehole (BGS Registration Number NT46NE/73) (NT 4570 6902), which provides a complete section from about 372 to 476 m depth.

Lower and upper boundaries[edit]

The base is conformable or locally unconformable on the North Berwick Pyroclastic Member. The change is from basaltic pyroclastic rocks to basic lavas.

The member is overlain by the Hailes Lava Member. The contact is conformable and locally unconformable. The change is from basalt and basanite and hawaiite to olivine basalt and mugearite.

Thickness[edit]

Between 0 and 90 m.

Distribution and regional correlation[edit]

East Lothian, outcrop of the Garleton Hills Volcanic Formation around North Berwick, East Linton, Garleton Hills, Stenton and in the subcrop farther west in the BGS Spilmersford Borehole (see above) near Pencaitland, but absent adjacent to the Lammermuir Fault.

Age[edit]

Early Visean (Chadian to Arundian).

References[edit]

  1. 1.0 1.1 McAdam, A D, and Tulloch, W.1985.Geology of the Haddington district.Memoir of the British Geological Survey, Sheet 33W, part 41 (Scotland)
  2. Davies, A, McAdam, A D, and Cameron, I B.1986.Geology of the Dunbar district.Memoir of the British Geological Survey, Sheet 33E and part of Sheet 41 (Scotland)