Method to detect Chaotic Transitions in Geological Time Series and searching for Signatures of Astronomical Chaos during the last 66 Ma.
Abstract
Climate changes in Earth's history were induced by cyclic variations of insolation received at the top of Earth' s atmosphere. These variations are driven by quasi-periodic changes in the Earth's orbit. Detected astronomically driven Milankovitch cycles recorded in sediments are used to generate age models of high accuracy. These age models are adjusted to astronomical solutions, which are based on the numerical integration of modern gravitational interactions in the Solar System. Due to the chaotic behavior of the Solar System, the duration over which Earth's orbital variations can be computed with confidence is limited. It is thus important to detect chaotic transitions in geological data, in order to verify and extend astronomical models. Chaotic transitions manifest themselves as a change of two resonant astronomical frequencies of Mars' and Earth's orbit. It is necessary to follow the evolution of eccentricity and obliquity amplitude modulation, which provide the 'fingerprint' of these transitions. We developed a method to assess three Laskar solutions and three different calculated resonance transitions: La93 (Laskar et al., 1993) with a computed chaotic transition between 25 and 28 Ma, La04 (Laskar et al., 2004) between 85 and 92 Ma and La10d (Laskar et al., 2011) with a transition between 43 and 46 Ma to demonstrate the possibility to detect transitions only on short eccentricity. This method could now be applied on geological datasets to search for evidences of astronomical chaos within 35 and 66 Ma.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMPP53D1228R
- Keywords:
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- 1165 Sedimentary geochronology;
- GEOCHRONOLOGYDE: 3270 Time series analysis;
- MATHEMATICAL GEOPHYSICSDE: 4910 Astronomical forcing;
- PALEOCEANOGRAPHYDE: 4946 Milankovitch theory;
- PALEOCEANOGRAPHY