Milankovitch cycles in banded iron formations constrain the Earth-Moon system 2.46 billion years ago

Astronomically calibrating early Ediacaran evolution

The current low-resolution chronostratigraphic framework for the early Ediacaran Period hampers a comprehensive understanding of potential trigger mechanisms for environmental upheavals and their connections to evolutionary innovation. Here, we establish a high-resolution astrochronological framework spanning ~57.6 million years of the early Ediacaran, anchored by the radioisotopic date of the Gaskiers glaciation onset, based on key sections from South China. Constrained by multiple radioisotopic dates, this framework precisely constrains the timing of the Marinoan deglaciation, Ediacaran Negative carbon isotope excursions 1 and 2 (EN1 and EN2), and key fossil assemblages (acanthomorphic acritarchs, Weng'an and Lantian biotas). These dates indicate the rapid termination of the Marinoan glaciation in South China within 106-107 years, while providing robust temporal evidence for the global synchroneity of EN1, EN2, and Marinoan deglaciation. The integrated chronology refines the age model for early Ediacaran biotic evolution, revealing that ecosystems gradually increased in complexity over multi-million-year timescales while global taxonomic diversity remained relatively stable, punctuated by rapid transitions to novel communities coinciding with biogeochemical perturbations.

Enhancing in search of Milankovitch cycles from stratigraphic record using convex optimization algorithm

Accurately identifying Milankovitch cycles has been a significant challenge in cyclostratigraphic studies, as it is essential for improving geochronology. This manuscript focuses on developing a method that distinguishes Milankovitch cycles from sedimentary noise to enhance stratigraphic precision. Despite their often-conspicuous magnitude, these periodicities frequently intertwine with noise, posing a challenge for conventional spectral analysis. Therefore, to address this issue, we have developed an algorithm that enhances the resolution of the Milankovitch signal by employing convex optimization in spectral analysis. To evaluate the effectiveness of this new algorithm, we applied it to four distinct types of local stratigraphy where the Milankovitch signal has been confirmed. These include the stratigraphic sections in the middle Miocene molluscan beds of Java and the Mahakam Delta, Pleistocene sediments of Hominin Flores, and the Towuti Lake in Sulawesi Island, Indonesia. Our findings demonstrate the preservation of all targeted signals, with a confidence level surpassing 99%. By setting the significance level to 1%, we can reject the null hypothesis, which assumes noise or the absence of a Milankovitch signal in the stratigraphic data being tested. The absence of deviations from the identified periodicities further strengthens the Milankovitch signal, underscoring the robustness of our algorithm. However, we acknowledge that achieving optimal results still hinges on the accurate selection of the initial parameters z and λ.

A 650-Myr history of Earth's axial precession frequency and the evolution of the Earth-Moon system derived from cyclostratigraphy

The preservation of Milankovitch cycles in the stratigraphic record provides independent geological information to study our ancient solar system and can be leveraged to constrain existing theoretical models. Here, we identify 34 high-quality cyclostratigraphic records spanning the past 650 million years and use them to infer the evolution of the Earth-Moon system through a Bayesian inversion method. We reconstruct the time evolution of Earth's axial precession frequency, lunar distance, length of day, and the periods of obliquity and climatic precession cycles. The results indicate an interval of high tidal energy dissipation in the Earth-Moon system at ~300 to 200 million years ago, and are broadly consistent with an independently calculated tidal evolution model. Our results provide an improved determination of the past periods of obliquity and climatic precession for astrochronology applications and yield important constraints on the history of tidal energy dissipation during the Phanerozoic Eon.

Earth-Moon dynamics from cyclostratigraphy reveals possible ocean tide resonance in the Mesoproterozoic era

Cyclostratigraphy is an important observational window into the history of the Earth-Moon system. However, there is limited information from the Mesoproterozoic era (1.0 to 1.6 billion years ago); accordingly, only weak constraints on Earth-Moon separation and tidal dissipation are available for this time. To close this knowledge gap, we analyze cyclostratigraphy from the Yemahe Formation (~1.2 billion years ago), Wumishan Formation (~1.5 billion years ago), and Chuanlinggou Formation (~1.6 billion years ago) in China. We use a Bayesian inversion method to analyze the three cyclostratigraphic sections. We combine previous results with these three estimates to construct an updated Earth-Moon system evolution and tidal dissipation history after 2.5 billion years ago. The results show a tidal dissipation peak that is consistent with the model predictions within the error range but also that there may be an additional resonance fluctuation in the Mesoproterozoic era.