Ocean tides of ancient oceans and the evolution of the Earth-Moon system

Abstract

Ocean tides cause an exchange of angular momentum between the Earth and the Moon, resulting in the lengthening of the day and the Moon moving away from the Earth. This process essentially governs the evolution of the Earth-Moon system. The extent of the ocean tides is largely subject to the prevailing resonance conditions. These depend on the tide-generating force, the Earth rotation rate, and the geometry of the oceans. During the history of the Earth, these quantities have changed significantly. However, there is a considerable research deficit regarding a differentiated reconstruction of the Earth’s history and especially the tides of earlier oceans and their impact on the Earth’s rotation. For the period ~620 million years (Myr) ago, the ocean tides are reconstructed in their spatial and temporal characteristics by a time step model. At the same time, the associated angular momentum transfer between Earth and Moon is computed. Geological proxy data provide information about the tidal spectrum of the Australian continental plate during this period. This data also document a shortened lunar distance and a shorter day of 21.9 hours. The simulations include the lunar and solar principal constituents of the tide-generating force (M2 , S2 , K1 , O1 ). In the early history of the Earth, a supercontinent known as Rodinia dominated the topography. This continent was located about ~620 Myr ago in the Southern Hemisphere, across the South Pole. The simulated ocean tides are qualitatively and quantitatively validated by observational data for current conditions. The tidal exchange of angular momentum between the Earth and the Moon is found to accelerate the Moon’s orbit. As a result, the Moon moves away from the Earth and the day length increases. This result aligns with observational data. Within reasonable limits, the spectral distribution of tides for the period ~620 Myr ago is supported by the geological data and our prior knowledge. The interpretation of the regional distribution of angular momentum transfer as a function of the land-water distribution and the associated oceanic tidal systems allows the complex influence of the land-water distribution on angular momentum transfer to be estimated. A reliable example is obtained by the effect of the single supercontinent Rodinia, which existed during most of the Neoproterozoic (~1000 to 539 Myr ago), on angular momentum exchange between Earth and Moon resulting from ocean tides. The results of the present study are considered a significant advance in the interdisciplinary geoscientific and astronomical research on the deep-time evolution of the Earth and the Earth-Moon system.