CE31 - Physique subatomique, sciences de l'Univers, structure et histoire de la Terre

Astronomical solution for the Mesozoic Era – AstroMeso

Astronomical solution for the Mesozoic Era

The AstroMeso project aims to go beyond the horizon of predictability of 60 Ma for the Solar System, and to provide the basis of an astronomical solution over the whole Mesozoic. This will only be possible by using the geological record as an input, in order to constrain the orbital solution. This will open a new era where the geological record will actually be used to retrieve the orbital evolution of the solar system.

Obtaining an orbital solution for the solar system beyond 60 Ma.

According to Milankovitch theory (Milankovitch, 1941), some of the large climatic changes of the past originate in the variations of the Earth’s orbit and of its spin axis resulting from the gravitational pull of the other planets. These variations can be traced over several millions of years (Ma) in the geological sedimentary records, although the mechanisms that transfer the forcing insolation to the sedimentary variations are not precisely known. After the pioneer work of Hays et al (1976), a large effort of the stratigraphic community has been devoted to the search of this astronomical imprint. Over the last three decades, the Earth’s orbital and spin solutions elaborated by the PI and his group (Laskar et al, 1993, 2004, 2011a) have been used in a collaborative effort that allowed to establish a geological timescale based on the astronomical solution for the Neogene (0-23 Ma) (Lourens et al, 2004; Hilgen et al, 2012). Nevertheless, extending this procedure through the Mesozoic Era (66-250 Ma) is difficult, as the solar system motion is chaotic (Laskar, 1989, 1990). It will thus not be possible to retrieve the precise orbital motion of the planets beyond 60 Ma from their present state (Laskar et al, 2011b).

This multidisciplinary project uses different approaches.

- We are looking to obtain the most precise solution possible for the movement of the solar system. To do this, we have developed an extremely precise model, INPOP, which is adjusted to all the available data, both on the ground and in space. The most spectacular constraints are obtained thanks to space missions. When a probe orbits a planet, radio data makes it possible to obtain Earth-planet distances with an accuracy of a few meters. The Cassini probe provided precise data of Saturn's position. Currently, the Juno probe, which has been orbiting Jupiter since 2016, makes it possible to obtain the Earth-Jupiter distance with an unmatched precision of a few meters. This INPOP solution is used to establish planetary ephemerides for astronomical purposes, and to reduce data from space probes when high precision is required, in particular for ESA's Gaia mission. The INPOP solution is then extended over 1 to 10 Ma, which serves as a starting point for long-term solutions which are then integrated over very long durations, up to 250 Ma and more.

It is not enough, however, to extend a solution over 250 Ma to obtain the evolution of the solar system over this period. Indeed, the movement of the planets is chaotic (Laskar, 1989, 1990), and it will not be possible to obtain a solution beyond 60 Ma starting from the only initial conditions provided by the present observations. Beyond 60 Ma, two approaches will be implemented:

- A statistical approach on a very large number of orbital solutions, all compatible with the best recent observation data of the planets.

- A search among these solutions for those which are compatible with the geological data already collected or that will be collected within the framework of Astromeso.

Publication of the new planetary ephemeris INPOP20a built on the basis of new Juno data, Mars Express. New positions of Uranus and Neptune recalibrated on the GAIA DR3 have been added.

Obtaining the variations of the delta13C around the Cenomanian-Turonian limit of the CRAIE 700 drilling of Poigny in the Paris basin (Boulila et al., Gl. Planet. Ch., 2020). The high resolution of 2 ka makes it possible to highlight the role of precession and short eccentricity in the variations of delta13C during OAE2

Statistical analysis of the chaotic diffusion of the solar system. Obtaining the density of probability and their uncertainty for the fundamental frequencies of the solar system which are the fundamental indicators which one finds in the sedimentary series.

Detailed analysis of the deformation of the Earth under the effect of masses of ice during the most recent 50 Ma. This element is a component of obtaining a precise solution for the calculation of the orientation of the spin axis of the Earth in the past.

Calculation of a new long-term reference solution based on INPOP20a, including deformation of the Earth, tidal effects in the Earth-Moon system and mass loss of the sun.

Statistical analysis of multiple variations around this reference solution.

Analysis of logging data from boreholes in the Paris Basin and data collected in the Vocontian Basin to obtain a constraint on planetary movements.

1. Boulila, S., Brange, C., Cruz, A.M., Laskar, J., Gorini, C., Reis, T.D., Silva, C.G., 2020. Astronomical pacing of Late Cretaceous third- and second-order sea-level sequences in the Foz do Amazonas Basin. Marine and Petroleum Geology 117, 104382.
2. A. Di Ruscio, A. Fienga, D. Durante, L. Iess, J. Laskar, and M. Gastineau. Analysis of Cassini radio tracking data for the construction of INPOP19a: A new estimate of the Kuiper belt mass. A&A, 640:A7, August 2020.
3. A. Fienga, A. Di Ruscio, L. Bernus, P. Deram, D. Durante, J. Laskar, and
L. Iess. New constraints on the location of P9 obtained with the INPOP19a planetary ephemeris. A&A, 640:A6, August 2020.
4. Hilgen, F., Zeeden, C., & Laskar, J. (2020). Paleoclimate records reveal elusive ~200-kyr eccentricity cycle for the first time. Global and Planetary Change, 103296. doi:10.1016/j.gloplacha.2020.103296
5. Boulila, S., Charbonnier, G., Spangenberg, J.E., Gardin, S., Galbrun, B., Briard, J., Le Callonnec, L., 2020. Unraveling short- and long-term carbon cycle variations during the Oceanic Anoxic Event 2 from the Paris Basin Chalk. Global and Planetary Change 186, 103126.
6. Galbrun, B., Boulila, S., Krystyn, L., Richoz, S., Gardin, S., Bartolini, A., Maslo, M., 2020. « Short » or « long » Rhaetian? Astronomical calibration of Austrian key sections. Global and Planetary Change, doi.org/10.1016/j.gloplacha.2020.103253.
7. M. Farhat, J. Laskar, G. Boué, 2021 : Constraining the Earth's Dynamical Ellipticity from Ice Age Dynamics, submitted, arXiv preprint arXiv:2103.14682
8. F Mogavero, J Laskar, 2021, Long-term dynamics of the solar system inner planets, A&A, in press, arXiv preprint arXiv:2105.14976
9. NH Hoang, F Mogavero, J Laskar, 2021, Chaotic diffusion of the fundamental frequencies in the Solar System, A&A, in press, arXiv preprint arXiv:2106.00584

10. Laskar, J. 2020, Astrochronology, in Geologic Time Scale 2020, Gradstein et al, eds, (Elsevier), 139–158

According to Milankovitch (1941) theory, some of the large climatic changes of the past originate in the variations of the Earth’s orbit and of its spin axis resulting from the gravitational pull of the other planets. These variations can be traced over several millions of years (Ma) in the geological sedimentary records, although the mechanisms that transfer the forcing insolation to the sedimentary variations are not precisely known. After the pioneer work of Hays et al (1976), a large effort of the stratigraphic community has been devoted to the search of this astronomical imprint. Over the last three decades, the Earth’s orbital and spin solutions elaborated by the PI and his group (Laskar et al, 1993, 2004, 2011a) have been used in a collaborative effort that allowed to establish for the Neogene (0-23Ma) a geological timescale based on the astronomical solution (Lourens et al, 2004; Hilgen et al, 2012). Nevertheless, extending this procedure through the Mesozoic Era (66-252 Ma) is difficult, as the solar system motion is chaotic (Laskar, 1989, 1990). It will thus not be possible to retrieve the precise orbital motion of the planets beyond 60 Ma from their present state (Laskar et al, 2011b).

For three decades, the astronomical orbital solutions elaborated by the PI have been used by geologists to establish local or global time scales. This project is specifically designed to achieve the opposite. We will use the geological record as an input to break the horizon of predictability of 60Ma which results from the chaotic nature of the orbital motion of the planets. This will be done in a quantitative manner, and aims to provide a template orbital solution for the Earth that could be used for paleoclimate studies over the Mesozoic Era. This will open a new era where the geological record will actually be used to retrieve the orbital evolution of the solar system.


This project stems from the achievement of Olsen et al (2019) where for the first time, in a study that involves the PI, it was possible to precisely recover the frequencies of the precessing motion of the inner planets (http://www.cnrs.fr/en/when-geology-reveals-solar-systems-past-secrets). At the same time, numerous studies appear involving very long sedimentary records (Ma et al, 2017, 2019). The objectives that many have dreamed for twenty years are thus now at hand. AstroMeso aims to go one step beyond by gathering a unique team with world leaders in celestial mechanics and planetary motions and world leaders in cyclostratigraphic analysis of long sedimentary records. AstroMeso will support two postdocs. One in astronomy for the search of an optimal orbital and insolation solution, and the other in geology, who will collect and analyse the best records. Both will work in close connection with the teams of the project, maintaining a strong interaction between astronomy and geology all along the duration of the project. This interdisciplinary, necessarily interdisciplinary, project, between geology and astronomy, searching to retrace the history of the Earth and the solar system trough the geological record, fits perfectly with the INSU-CNRS will to develop transversality around fundamental questions.

Project coordination

Jacques Laskar (Institut de Mécanique Céleste et de Calcul des Éphémérides, Observatoire de Paris)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

Géoazur Géoazur
LDEO Columbia University / Lamont-Doherty Earth Observatory
UUFG Utrecht University / Faculty of Geosciences
ISTEP Institut des sciences de la Terre Paris
LIAG Leibniz Institute for Applied Geophysics
CSH University of Bern Center for Space and Habitability
IMCCE Institut de Mécanique Céleste et de Calcul des Éphémérides, Observatoire de Paris

Help of the ANR 494,274 euros
Beginning and duration of the scientific project: December 2019 - 48 Months

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