GSSP for the Base of Aeronian


Definition:

The base of the Aeronian Stage is defined in the Trefawr Track section, 500m north of Cwm-coed-Aeron Farm, Wales, where it coincides with the base of the Monograptus triangulatus Biozone.


Location:

The GSSP is located in the Trefawr Track section, 500m north of Cwm-coed-Aeron Farm, Wales, UK.
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Sedimentology:

The GSSP lies within the gently-dipping blocky mudstones of the Trefawr Formation, which principally yield abundant and diverse shelly faunas, but also contain enough graptolites to allow recognition of several biozones.
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Primary Markers:

The base of the Monograptus triangulatus biozone is represented by the incoming of Monograptus austerus sequens.

Secondary Markers:

Graptolites:
Monograptus austerus vulgaris and Diplograptus elongatus occur in the cyphus Biozone, just below the stage boundary.

Other Locations around the World:

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

References:

Cocks, L. R. M., 1989. The Llandovery Series in the Llandovery 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. 36 50, Cardiff.