Informe preliminar sobre la presencia de trilobites hirnantienses (Ordovícico terminal) en las Pizarras de Orea de las Cadenas Hespéricas (NE de España)
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[1] Universidad de Zaragoza
Universidad de Zaragoza
Zaragoza, España
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- Localización: Geotemas (Madrid), ISSN 1576-5172, Nº. 6, 2, 2004 (Ejemplar dedicado a: IV Congreso Geológico de España), págs. 315-317
- Idioma: español
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Resumen
Hirnantian trilobites have been recovered from the glaciomarine Orea Shales, in the Hesperian Chains of the Iberian Ranges (NE Spain). They occur in the lowermost strata of the unit, in poorly stratified, grey to black claystones lacking the quartz grains and pebbles typical of other outcrops of the formation. The trilobites have been collected in one locality from the Tremedal massif, which has yielded Mucronaspis mucronata. This species is pandemic and constitutes the most frequent trilobite of the Hirnantia fauna, although its origin is slightly earlier. The presence of trilobite fauna in this point may be related to the extremely fine-grained character of the Orea Shales by comparison with other areas where the input of coarser grained clasts has been recorded, and would represent hemipelagic deposition in the distal part of the Hesperian platform.
