Back to the Future II: Tidal evolution of four supercontinent scenarios

Abstract

Abstract. The Earth is currently 180 Ma into a supercontinent cycle that began with the breakup of Pangea, and will end in around 200–250 Ma (Mega-annum) in the future, as the next supercontinent forms. As the continents move around the planet, they change the geometry of ocean basins, and thereby modify their resonant properties. In doing so oceans move through tidal resonance, causing the global tides to be profoundly affected. Here, we use a dedicated and established global tidal model to simulate the evolution of tides during four future supercontinent scenarios. We show that the number of tidal resonances on Earth vary between 1 and 5 in a supercontinent cycle, and that they last for no longer than 20 Ma. They occur in opening basins after about 140–180 Ma, an age equivalent to the Present-Day Atlantic Ocean, which is near resonance for the dominating semi-diurnal tide. They also occur when an ocean basin is closing, highlighting that in its lifetime, a large ocean basin – its history described by the Wilson cycle – may go through two resonances: one when opening and one when closing. The results further support the existence of a super-tidal cycle associated with the supercontinent cycle, and gives a deep-time proxy for global tidal energetics.

The Climates of Earth’s Next Supercontinent: Effects of Tectonics, Rotation Rate, and Insolation

“…There are many uncertainties, but recent work provides some guidelines (Mello & Friaça, 2019). The reduced tides during the supercontinent stage (Davies et al., 2020) will lead to reduced vertical mixing rates, that is, a reduced vertical diffusivity in the abyssal ocean (Munk, 1966; Wunsch & Ferrari, 2004). This may have implications for ocean ecosystems, and biodiversity.…”

“…In both cases the ocean bathymetry was kept as in Davies et al. (2020), with continental shelf seas 150 m deep, mid‐ocean ridges 1,600 m deep at the crest point and deepening to the abyssal plains within , and trenches 6,000 m deep. The abyssal plain was set to a depth maintaining the present day ocean volume.…”