In the geologic timescale, the Aeronian is an age of the Llandovery Epoch of the Silurian Period of the Paleozoic Era of the Phanerozoic Eon that began 440.8 ± 1.2 Ma and ended 438.5 ± 1.1 Ma (million years ago). The Aeronian Age succeeds the Rhuddanian Age and precedes the Telychian Age, all in the same epoch.[7]
Aeronian | |||||||||||||
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Chronology | |||||||||||||
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Etymology | |||||||||||||
Name formality | Formal | ||||||||||||
Usage information | |||||||||||||
Celestial body | Earth | ||||||||||||
Regional usage | Global (ICS) | ||||||||||||
Time scale(s) used | ICS Time Scale | ||||||||||||
Definition | |||||||||||||
Chronological unit | Age | ||||||||||||
Stratigraphic unit | Stage | ||||||||||||
Time span formality | Formal | ||||||||||||
Lower boundary definition | FAD of the graptolite Demirastrites triangulatus | ||||||||||||
Lower boundary GSSP | Hlásná Třebaň section, Czech Republic | ||||||||||||
Lower GSSP ratified | 2024[4][5] | ||||||||||||
Upper boundary definition | FAD of the graptolite Spirograptus guerichi | ||||||||||||
Upper boundary GSSP | El Pintado section, Seville, Spain | ||||||||||||
Upper GSSP ratified | 2024[4][6] |
During the Aeronian the Sedgwickii Event occurred in which graptolite diversity was greatly reduced.[8] This event has been attested in locations such as today's Canada, Libya as well as in La Chilca Formation in Argentina (then part of Gondwana).[8]
The GSSP is located in the Trefawr Track section, 500m north of Cwm-coed-Aeron Farm, Wales, UK.[9] 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.[10]
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