Ultra-fine magnetostratigraphy of Cretaceous shallow water carbonates, Monte Raggeto, southern Italy

Abstract

Abstract The sedimentological and palaeomagnetic parameters of bore cores of shallow-water Hauterivian and Barremian carbonates have been defined at 1 cm and 2 cm intervals, respectively. The stability of remanence to alternating fields has been established and a composite 88 m sequence compiled. This shows fine structure polarity changes, with the Hauterivian section being almost entirely of Normal polarity and the Barremian including thick zones of both predominantly Normal and Reversed polarity. Narrow zones of opposite polarity occur throughout. The sedimentological and palaeomagnetic properties are found to exhibit clear cyclicities, which, when normalized, show an extremely high correlation to each other and to the predicted orbital variations for this period. This enables a study of polarity transitions and secular variations using a chronology in which 1 cm is equivalent, on average, to 285 ± 8 years.