Analysing the tidal state of a pre-plate tectonic Earth during the Archean Eon (3.9 Ga)
- 1Instituto Dom Luiz (IDL), Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal, (hdavies@fc.ul.pt)
- 2Departamento de Geologia, Faculdade de Ciências, Universidade de Lisboa, Lisbon, Portugal
- 3School of Ocean Sciences, Bangor University, Menai Bridge, UK
- 4School of Earth, Atmosphere and Environment, Monash University, Melbourne, Victoria, Australia
Deep time investigations of the Earth have revealed a relationship between plate tectonic motion and the intensity of the tide. Tidal energetics change as continental plates disperse and aggregate in the supercontinent cycle, altering ocean basins around them. The question is, could enhanced tides occur on Earth before plate tectonics started e.g., during the Archean?
Here we have coupled an established tidal model with an ensemble of potential topographies of the Archean Earth to establish a statistically significant approximation of Archean tidal energetics. Land area is restricted to 5 – 15% with the rest representing primordial ocean – containing no major plate tectonic features i.e., trenches and ridges. Ocean volume is preserved at close to present-day which means oceans are on average 1 km shallower than present-day oceans. Archean day length is set at 13.1 hours with the semi-diurnal tide occurring every 6.8 hours. Equilibrium tide is around 3.4x the present-day value due to the proximity of the Moon.
The aim of this study is to assess the relationship of the Earth Moon system during this primordial stage to better understand the potential role tides had in the origin of life, and to quantify the tidal state of a primordial rocky planet with a young, nearby moon. Understanding the tidal state of Earth at this early time is important for exoplanetary studies as it broadens our scope of planets which may be hospitable to life.
We found coastal and open ocean resonance in many of the ensemble topographies. Total global dissipation in the ensembles varies from 75 – 150% of present-day dissipation rates due to elevated equilibrium tide and greater area where the tide can dissipate. When regional and open ocean resonance does occur, it can raise total global dissipation to >150% of present-day values and can caue regional macrotidal amplitudes (>2m).
The authors would like to acknowledge funding support from FCT – UIDB/50019/2020 – IDL.
How to cite: Davies, H., Green, M., and Duarte, J.: Analysing the tidal state of a pre-plate tectonic Earth during the Archean Eon (3.9 Ga), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1582, https://doi.org/10.5194/egusphere-egu21-1582, 2021.
