The Neuquen composite section: Magnetostratigraphy and biostratigraphy of the marine lower Jurassic from the Neuquen basin (Argentina)

Abstract

Paleomagnetic and biostratigraphic data from five marine sedimentary sections in the Argentine Neuquen basin have allowed to construct the Lower Jurassic Neuquen Composite Section. This composite section comprises 14 reversed and 11 normal polarity Zones, in relation to 17 Andean ammonite Assemblage Zones, spanning the Hettangian-Toarcian (Early Jurassic). It represents the first paleomagnetic data of Lower Jurassic marine successions in the Southern Hemisphere. The Neuquen composite Section was correlated to the International Mesozoic Polarity Time Scale which, for the Lower Jurassic, comprises 54 polarity Zones and 16 Standard ammonite Zones. The correlation between the regional and the international biomagnetostratigraphic scales supports but also refines the correlation between the Andean and Standard ammonite zonations. Correlation between the Neuquen composite Section and the polarity sequences recorded in each section helped to assign several unfossiliferous stratigraphical levels to the corresponding biozones. (C) 2000 Elsevier Science B.V. All rights reserved.