North Atlantic Drift Sediments Constrain Eocene Tidal Dissipation and the Evolution of the Earth‐Moon System

Abstract

Cyclostratigraphy and astrochronology are now at the forefront of geologic timekeeping. While this technique heavily relies on the accuracy of astronomical calculations, solar system chaos limits how far back astronomical calculations can be performed with confidence. High-resolution paleoclimate records with Milankovitch imprints now allow reversing the traditional cyclostratigraphic approach: Middle Eocene drift sediments from Newfoundland Ridge are well-suited for this purpose, due to high sedimentation rates and distinct lithological cycles. Per contra, the stratigraphies of Integrated Ocean Drilling Program Sites U1408-U1410 are highly complex with several hiatuses. Here, we built a two-site composite and constructed a conservative age-depth model to provide a reliable chronology for this rhythmic, highly resolved (<1 kyr) sedimentary archive. Astronomical components (g-terms and precession constant) are extracted from proxy time-series using two different techniques, producing consistent results. We find astronomical frequencies up to 4% lower than reported in astronomical solution La04. This solution, however, was smoothed over 20-Myr intervals, and our results therefore provide constraints on g-term variability on shorter, million-year timescales. We also report first evidence that the g 4 -g 3 "grand eccentricity cycle" may have had a 1.2-Myr period around 41 Ma, contrary to its 2.4-Myr periodicity today. Our median precession constant estimate (51.28 ± 0.56″/year) confirms earlier indicators of a relatively low rate of tidal dissipation in the Paleogene. Newfoundland Ridge drift sediments thus enable a reliable reconstruction of astronomical components at the limit of validity of current astronomical calculations, extracted from geologic data, providing a new target for the next generation of astronomical calculations.

A Secular Solar System Resonance that Disrupts the Dominant Cycle in Earth’s Orbital Eccentricity (g 2 − g 5): Implications for Astrochronology

“…The two approaches made essentially no difference in our computations and both yielded solutions including σ 12 -resonance intervals at a similar frequency (see below). For the observational constraints on R, we selected robust data sets based on the reconstruction of Earth's axial precession frequency obtained by cyclostratigraphic studies (Meyers & Malinverno 2018;Sørensen et al 2020;Lantink et al 2022;De Vleeschouwer et al 2023; see Figure 3). The classical integration of precession equations starting at the present rate dR 0 /dt (see Figure 3, green dashed line) follows MacDonald (1964); Goldreich (1966); Touma & Wisdom (1994).…”

Milanković Forcing in Deep Time

“…Note that due to its small effect, selecting OS input option 1 or 2 for a L made essentially no difference in our long-term OS ensembles. For the observational constraints, we selected robust data sets based on the reconstruction of Earth's axial precession frequency obtained by cyclostratigraphic studies (Meyers & Malinverno, 2018;Sørensen et al, 2020;Lantink et al, 2022;De Vleeschouwer et al, 2023) (Figure 1b). Other methods for estimating past a L (and precession frequency) include the analysis of tidal rhythmites and fossil growth laminae, but these approaches are generally associated with large uncertainties and ambiguities in interpretation, especially for Precambrian time intervals (Lantink et al, 2022;Laskar et al, 2024).…”

“…If restricted to robust data sets from cyclostratigraphic studies, only two data points are available with ages older than 1 Ga (see Figure 1b). For more information on the cyclostratigraphic studies (Meyers & Malinverno, 2018; Sørensen et al, 2020; Lantink et al, 2022; De Vleeschouwer et al, 2023), see Section 3.7.…”

North Atlantic Drift Sediments Constrain Eocene Tidal Dissipation and the Evolution of the Earth-Moon System.

“…The NAFF software is available through https://paloz.marum.de/confluence/ display/ESPUBLIC/NAFF (Pälike, 2021b). The R scripts used to generate Figures 4-12 are available through Zenodo (De Vleeschouwer, 2023).…”