New insight on the age and significance of the Aparein black shales in the Basque-Cantabrian Basin, northern Spain

This paper re-interprets the ammonite record and carbon-isotope signals associated with the Aparein black shales (Lareo Formation) from the Sierra de Aralar Massif (Basque-Cantabrian Basin, northern Spain). An early late Aptian age (upper Epicheloniceras martini Zone) is re-assigned to the Aparein level. Its regional correlation is discussed. As herein suggested, the Aparein level is coeval to the Seberetxe level occurring in the Bilbao Formation from the nearby Bilbao area. The Aparein and Seberetxe levels are correlative to the Fallot black shales in the Blue Marls Formation of southeast France (Vocontian Basin), regarding both ammonite and carbon-isotope signal. The new age calibration will help in identifying the parameters that controlled organic matter enrichments in northern Spain and southeast France during the early late Aptian.

Automated summary

This paper re-interprets the age and stratigraphic correlation of the Aparein black shales in the Sierra de Aralar Massif in northern Spain, suggesting a correlation with the Seberetxe level in the nearby Bilbao area and the Fallot black shales in the Blue Marls Formation of southeast France. This new age calibration provides insights into the parameters controlling organic matter enrichments in the early late Aptian in northern Spain and southeast France.