The Building of a Magnetostratigraphic Framework: Lessons Learned from the Ebro Foreland Basin (Paleogene-Neogene, NE Spain)

Abstract:

The extensive rock outcrops spanning the complete basin fill of the South-Pyrenean foreland make this region best suited for magnetostratigraphic analysis. Over the last decades, a biochronological framework, based fundamentally on fossil benthic foraminifera and vertebrates, is being replaced with a magnetostratigraphy-based chronology. The increasing length of the composite record has allowed magnetostratigraphic correlation to work with decreasing dependence on existing biostratigraphic constraints. This has provided integrated basin studies with a time frame of unprecedented resolution, crucial to unravel the interactions and causal relationships between the diverse forcing mechanisms involved in basin formation and filling. In the ideal progress towards an independent magnetochronological framework, a fundamental issue arises recurrently: To which extent biochronological information should limit the solutions of magnetostratigraphy? The answer to this question is not simple since the chronostratigraphic significance and age accuracy of key bioevents needs to be addressed in a case-by-case basis. In the other hand, the continuity and steadiness of the sedimentary record, which is hardly assessed a priori, reveals crucial for magnetostratigraphic correlation to work. Examples from the Eocene to Miocene of the Ebro Basin illustrate the need for an effort of a basin-scale integration of all (lito-, bio- and magneto-) stratigraphic disciplines.