Long-period orbital climate forcing. Cyclostratigraphic studies of Cenozoic continental and marine successions in Europe. Geologica Ultraiectina (297)

Abstract

Orbital climate forcing is well-known for its strong impact on Earth’s climate as for example the switching from glacial to inter-glacial states in the Late Pleistocene. Typical ‘Milankovitch’ cycles are climatic precession (21.000 years or 21 kyrs), obliquity (41 kyrs), and short and long eccentricity (circa 100 and 405 kyrs). Million-year scale astronomical cycles are as well present in eccentricity modulation of precession amplitude (0.97 and 2.4 Myrs) and in obliquity amplitude modulation (1.2 Myrs). These long-period cycles have been suggested to imprint Earth’s climate in the past, although to date direct prove is scarce in marine and absent in non-marine settings. Here, cyclostratigraphic studies have been performed to Cenozoic marine and continental successions in Europe all aimed at examination the impact of long-period orbital climate forcing. The results substantiate that long-period obliquity climate forcing played a major role in the timing of the middle Miocene global cooling as recorded in marine sediments on Malta. Our results of the Madrid in Spain reject the imprint of this long-period obliquity forcing on the Miocene infill. Nevertheless, the formation-scale genetic red bed – limestone sequences in the continental basin might be related to low frequency eccentricity cyclicity. The data from the Late Miocene infill of the continental Teruel Basin remarkably reveal a similar orbital configuration for the transition from red bed to limestone successions as in the Madrid Basin. However, enhanced sediment supply related to the entrance of an axial fluvial system time-equivalent at the other basin margin might rather suggest a local geomorphic or tectonic origin of the transition instead of climate change. The sediment record of the shallow marine succession of the Boom Clay Formation is too short and poorly dated to investigate the presence of low frequency astronomically forced variability, although high frequency glacio-eustatic sea level variations driven orbital forcing are now well depicted.