Deep-water fallout tephra deposits in the Black Flysch of Deba (Upper Albian, Basque-Cantabrian Basin)

• Autores: Luis M. Agirrezabala Mundiñano, Joaquín García Mondéjar
• Localización: Geotemas (Madrid), ISSN 1576-5172, Nº. 3, 2, 2001 (Ejemplar dedicado a: XIV Congreso Nacional de Sedimentología, IV Congreso del Cretácico de España), págs. 123-126
• Idioma: español
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• Resumen

  • Upper Albian deposits of the Deba section consist mainly of deep-water turbiditic sandstones and lutites (Black Flysch). In the uppermost part of this section (-120 m), several tens of tephra layers are intercalated between lutites. They are 0.5-18 mm thick tabular layers of tuff and lapiHistone.

    Three pyroclastic facies have been distinguished: normal graded tuff/lapiHistone (the most abundant), disorganised lapillistone and normal graded to disorganised tuff/lapi Histone. These facies exhibit characteristics typical of fallout tephra deposits: non-erosive sharp and flat base, lack of lamination, uniformity and lateral wide extent, normal gradation, and lack of terrigenous particles and rip-up clasts. Sedimentological and regional criteria suggest a southern source area for these fallout pyroclastic deposits.