REGIONAL CORRELATION AND CYCLOSTRATIGRAPHY IN THE MID-CRETACEOUS FORMATIONS OF THE IONIAN ZONE

Abstract

The mid-Cretaceous period is characterized by the widespread deposition of organic carbon-rich horizons, documenting oceanic anoxic events (OAEs), which correspond to episodes of major disturbances in the carbon cycle. The causes of these events are still widely debated. In this study, the role of orbital variations in the deposition of black shales in the Ionian Zone (Western Greece), an area already known for documenting OAEs is examined. Cyclostratigraphic data for the Lower Aptian interval are interpreted in a climate change context, and specific mechanisms for the deposition of organic carbon-rich horizons are hypothesized. Field observations, stable isotope and total organic carbon analyses, as well as biostratigraphic data enable a correlation between the Gotzikas section and the Paliambella section, also in the Ionian Zone (Epirus, Greece). In addition, Gotzikas section is also correlated with the Poggio le Guaine - Fiume Bosso composite sequence of the Umbria - Marche region (Italy). Lower Aptian sedimentation in the Ionian Basin seems to be controlled by orbital forcing. The short eccentricity and obliquity rhythms are most prominently recorded. Whilst the presence of amplitude modulation cycles indicates towards a lesser control by the long eccentricity and precession periodicities.