GSSP for the Base of Ludfordian


Definition:

The base of the Ludfordian Stage is located at Sunnyhill Quarry, near Ludlow, Shropshire, UK.



Location:

The GSSP is located at Sunnyhill Quarry (SO 4950 7255) about 2.5km south-west of Ludlow town, Shropshire, UK. From Ludlow it is reached by the A49 and B4361 roads.
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Sedimentology:

The Upper Bringewood Formation (Gorstian) consists of nodular silty limestone. The succeeding Lower Leintwardine Formation (Ludfordian) is lithological similar, but faunally distinct. The GSSP for the Ludfordian is represented as a thin shale seam, coincident with the base of the Leintwardine Formation.
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Fossil Markers:

Graptolites: The most important incoming species above the GSSP is Saetograptus leintwardinensis leintwardinensis.
Acritarchs: Dorning’s (1981) acritarch Biozone boundary L2/L3 is positioned slightly below the Gorstian-Ludfordian boundary. The incoming species of the L3 biozone are: Cymbosphaeridium pilaris, Leoniella carminae, Multiplicisphaeridium paraquaferum, Veryhachium leintwardinensis, and Leiofusa estrecha.

At or near the base of the Ludfordian Stage the following fossils either disappear or become very rare:
Brachiopods: Kirkidium knightii, Strophonella euglypha
Solitary corals: D. myops, P.globosa



Other Locations around the World:

See: Holland, C. H. and Bassett, M. G., 1989 (eds.). A global standard for the Silurian System. National Museum of Wales, Geological Series 9, Cardiff.

References:

Dorning, K. J., 1981. Silurian acritarchs from the type Wenlock and Ludlow of Shropshire, England. Review of Palaeobotany and Palynology 34, p. 175 – 203.

Lawson, J. D. and White, D. E., 1989. The Ludlow Series in the Ludlow Area. In: Holland, C. H. and Bassett, M. G. (eds.). A global standard for the Silurian System. National Museum of Wales, Geological Series 9, p. 73 - 90, Cardiff.