Gordale Limestone Member

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Gordale Limestone Member (GDLL), Carboniferous, Northern England Province[edit]

Gordale Limestone Member is a member of the Malham Formation and part of the Great Scar Limestone Group

Name[edit]

The member is named from the limestone at Gordale Scar (SD 913 640) (see Arthurton et al., 1988[1]; Mundy and Arthurton, 1980[2]).

Lithology[edit]

Scar-forming, mid–pale to very pale grey limestone, well bedded, varying from thick- to very thick-bedded. Variations include fine- and medium-grained (more rarely coarse-grained) bioclastic calcarenite packstones, wackestones and subordinate grainstones, with thin conglomerates adjacent to the Middle Craven Fault. The wackestones and packstones commonly show pseudobrecciation and the grainstones are cross-bedded. Undulating palaeokarstic surfaces are present, commonly overlain by thin clays (bentonites). Topographically, the member forms conspicuous stepped scar-features and prominent limestone pavements.

Stratotype[edit]

The type section is at Gordale Scar (SD 913 640) where the complete thickness (94 m) of the Gordale Limestone Member, including top and base is seen (see Arthurton et al., 1988[1]).

Lower and upper boundaries[edit]

The lower boundary is taken at a conspicuous bedding plane at the base of the scar-forming pale grey, well-bedded limestone of the Gordale Limestone Member above the pale grey massive limestone of the Cove Limestone Member.

The conformable upper boundary is drawn at the upward passage from pale grey limestone of the Gordale Limestone Member to darker grey limestone of the Lower Hawes Limestone at the base of the Alston Formation, Yoredale Group (Figure 15, Column 6).

Thickness[edit]

Some 94 m in its type section at Gordale Scar (SD 913 640). Elsewhere a thickness of 70–75 m is typical.

Distribution

Southern part of the Askrigg Block, north of Settle (SD 77 to SD 97).

Age and biostratigraphical characterisation[edit]

Asbian. Typical Asbian fossils in the Gordale Limestone Member include Dibunophyllum bourtonense, Davidsonina septosa and Delepinea comoides. Diagnostic foraminifers also occur.

References[edit]

  1. 1.0 1.1 Arthurton, R S, Johnson, E W, and Mundy, D J C.1988.Geology of the Country around Settle.Memoir of the British Geological Survey, Sheet 60 (England and Wales).
  2. Mundy, D J C, and Arthurton, R S.1980.Field meetings: Settle and Flasby.Proceedings of the Yorkshire Geological Society, Vol. 43, 32–36.