Tides and Earth-Moon system evolution are coupled over geological time. Tidal energy dissipation on Earth slows Earth Es rotation rate, increases obliquity, lunar orbit semi-major axis and eccentricity, and decreases lunar inclination. Tidal and core-mantle boundary dissipation within the Moon decrease inclination, eccentricity and semi-major axis. Here we integrate the Earth-Moon system backwards for 4.5 Ga with orbital dynamics and explicit ocean tide models that are "high-level" (i.e., not idealized). To account for uncertain plate tectonic histories, we employ Monte Carlo simulations, with tidal energy dissipation rates (normalized relative to astronomical forcing parameters) randomly selected from ocean tide simulations with modern ocean basin geometry and with 55, 116, and 252 Ma reconstructed basin paleogeometries. The normalized dissipation rates depend upon basin geometry and Earth E s rotation rate. Faster Earth rotation generally yields lower normalized dissipation rates. The Monte Carlo results provide a spread of possible early values for the Earth-Moon system parameters. Of consequence for ocean circulation and climate, absolute (un-normalized) ocean tidal energy dissipation rates on the early Earth may have exceeded today E s rate due to a closer Moon. Prior to E 3 Ga, evolution of inclination and eccentricity is dominated by tidal and core-mantle boundary dissipation within the Moon, which yield high lunar orbit inclinations in the early Earth-Moon system. A drawback for our results is that the semi-major axis does not collapse to near-zero values at 4.5 Ga, as indicated by most lunar formation models. Additional processes, missing from our current efforts, are discussed as topics for future investigation. Plain Language Summary Tidal dissipation ins oceans and solid body cause the distance to the Moon and the length of day to increase over time. Tides also change the eccentricity and tilt of the lunar orbit, and Earth E s obliquity (the tilt between the equator plane and the ecliptic plane of our orbit around the Sun). This paper attempts to calculate the evolution of the Earth-Moon system over the whole of Earth E s history using sophisticated ocean tide and orbit models. Over long time scales, the rate at which tidal energy is being dissipated is affected by the geometrical configuration of the continents, the length of day, and mean sea level, which is affected by plate tectonic forces and the presence or absence of large ice caps. The faster rotating Earth of the past was less efficient at dissipating energy and the present placement of the continents enhances some tides due to resonances. In addition, tidal dissipation in the Moon slows the orbit evolution by absorbing energy from the orbit and there was a time in the distant past when the Moon s E tidal dissipation was large. The evolution of the Earth-Moon system is complex and uncertain, but it can be addressed with advanced models.
The theory of plate tectonics and the discovery of large scale, deep-time cycles, such as the Supercontinent cycle and Wilson cycle, has contributed to the identification of several supercontinents in Earth's history. Using the rules of plate tectonic theory, and the dynamics of subduction zones and mantle convection, it is possible to envisage scenarios for the formation of the next supercontinent, which is believed to occur around 200-300 Ma into the future. Here, we explore the four main proposed scenarios for the formation of the next supercontinent by constructing them, using GPlates, in a novel and standardised way. Each scenario undergoes different modes of Wilson and Supercontinent cycles (i.e., introversion, extroversion, orthoversion, and combination), illustrating that the relationship between them is not trivial and suggesting that these modes should be treated as end-members of a spectrum of possibilities. While modelling the future has limitations and assumptions, the construction of the four future supercontinents here has led to new insights into the mechanisms behind Wilson and Supercontinent cycles. For example, their relationship can be complex (in terms of being of the same or different order, or being in or out of phase with each other) and the different ways they can interact may led to different outcomes of large-scale mantle reorganization. This work, when combined with geodynamical reconstructions since the Mesozoic allows the simulation of the entire present-day Supercontinent cycle and the respectively involved Wilson cycles. This work has the potential to be used as the background for a number of studies, it was just recently used in tidal modelling experiments to test the existence of a Supertidal cycle associated with the Supercontinent cycle.
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