Bangley Trachytic Member: Difference between revisions

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Bangley Trachytic Member (BYTRC), Carboniferous, Midland Valley of Scotland

Bangley Trachytic Member is part of the Garleton Hills Volcanic Formation

Name

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

Lithology

The Bangley Trachytic Member consists of purple and blue-grey trachytic lavas with both feldspar-phyric (sodic plagioclase to sanidine) and aphyric types. Individual flows are known to be over 20 m thick. Quartz-trachytes are also present. Red, brown and purple trachytic tuff and lapilli-tuff with agglomerate and some volcaniclastic sedimentary rocks also are interbedded in units known to be at least 8 m thick.


Stratotype

The type area is East Lothian (NT 4500 6900 to 6000 7300) 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]), and in the Spilmersford Borehole (BGS Registration Number NT46NE/73) (NT 4570 6902), which provides a complete section from about 286 to348 m depth.

Lower and upper boundaries

The base is apparently conformable on the Hailes Lava Member, which consists of basaltic lavas and volcaniclastic rocks.

The member is overlain by the siliciclastic sedimentary rocks of the Gullane Formation (Strathclyde Group). The contact is considered unconformable with volcaniclastic conglomerate recorded locally at the base of the overlying formation.

Thickness

Between 0 and 160 m.

Distribution and regional correlation

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

Age

Early Visean (Chadian to Arundian).

References

  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)