Señales geoquímicas y micropaleontológicas como marcadores de eventos paleoceanográficos en el Santoniense del Arco Vasco

Abstract

Comparative study of micropalaeontologic (planktonic and benthic foraminifers) and isotopic (8,80 and 5'3C values from inoceramids and whole rock) data from the Santonian of the Barrika section (Basque Arc, northern Spain) shows the existence of four events, each one with different biotic and geochemical signals. Diagenetic alteration of isotopic profiles (5,eO and 8I3C) have not been so severe to delete completely the geochemical signals from inoceramids and whole rock. As a consequence, events 1st, 2nd and 3rd show a 5lsO positive excursion (cooling) and sea level falls; however the 4th event marks a global regression at 85 m.y., that could have caused strong local alteration of the planktonic and benthic foraminifer assemblages. In this case, the eustatic fall shows a S'0O negative excursion, that could be related to meteoric cementation, due to sea level lowstand