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The study proposes a connection between the formation of supercontinents and the strength of the tides

The tides of the earth were not always as energetic as they are today. A recent study suggests that when tectonic movements shape ocean basins into specific shapes, the tides grow much more. And if the tectonic movements open the same pools millions of years later, the tides weaken. Credit: Creative Commons CC0.

The cyclical strengthening and weakening of the sea tides over several tens of millions of years is probably linked to another, longer cycle: the formation of supercontinents of the Earth every 400 to 600 million years, according to a new study. According to the authors of the study, the new findings have consequences for the formation of our planet, its climate and the development of life on earth. The new research suggests long-term changes in tidal energy that control the strength of ocean waves are part of a super-tidal cycle dictated by the movement of the tectonic plates.

When tectonic plates slide, sink and shift the continents of the earth to form large land masses or supercontinents, ocean basins open and close in tandem. When these basins change their shape, they can hit shapes that intensify and intensify their tides.

In the new study, tidal simulations projected hundreds of millions of years into the future suggest that the Earth is at the very stage of tidal maximum, where strong tides persist for approximately 20 million years. The oceans will go through several tidal cycles, while the next supercontinents will form over the next 250 million years. Finally, the tides will be much weaker, just as with the two youngest supercontinent Pangea and Rodinia, says the new study Geophysical Research Letters a journal of the American Geophysical Union. [1

9659005] Scientists knew that tidal energy varied in the distant past, but the new study suggests that over geological timescales there is a super-tidal cycle associated with tectonic movements.

"Our simulations indicate that the tides are present, unusually large," said oceanographer Mattias Green of Bangor University's School of Ocean Sciences at Menai Bridge in the UK and lead author of the new study. "And that was really our motivational question: if the tides were weak until 200 million years ago and they've been increasing dramatically in the last two million years, what will happen if we pull millions of years into the desert?" The tidal force is linked to life on earth, and the understanding of the cyclical evolution of the ocean, according to the authors of the study for the understanding of evolutionary theory by the scientists. In times of strong tidal energy, as today, strong waves stir the sea and create the nutrient mixture needed to sustain life in the ocean. As the earth's landmasses slowly move toward a supercontinent configuration, the ocean basins of the planet open up to form an uninterrupted body of water. Such a sea would have a low tidal energy. Weak waves mean that there is less nutrient mixing, which could create an oxygen depleted seabed that is largely depleted of life, much like a pool of stagnant water, according to the new study.

The existence of this cycle and its connection to tectonic Englisch: bio-pro.de/en/region/stern/magazine/…3/index.html said geophysicist Dietmar Müller of the University of Sydney in Australia, who was not involved in the new study.

"It probably means nothing to people now in our lives," Muller said. "But it does improve our understanding of the interactions between plate tectonics, the Earth's climate system, its oceans, and even how the evolution of life is at least partially driven by this tidal process."

Changing continents, ocean basins

Each of the continents of the earth rides on huge plates known as tectonic plates. These plates move for hundreds of millions of years, encountering different continental configurations.

Tectonic plates determine the shape and arrangement of continents, but also determine the shape of ocean basins. As the North American and Eurasian plates drift apart, the Atlantic Ocean expands between them and also changes shape.

The change in the shape of the ocean basins causes a change in a property known as resonance. When a pool is resonant, the energy from the moon's attraction matches the length of the ocean basin, causing an increase in tidal energy.

Green represents the resonance of a child on a swing. A swinging child only needs a small push from an adult at the right time to keep the momentum higher and higher. "You force it on the same frequency as the natural vibration, and the same happens in the ocean," he said.

A Tectonic Timeline

In the new study, scientists simulated the movement of the Earth's tectonic plates and changes in ocean basin resonance over millions of years.

The new research suggests that the Atlantic Ocean is currently resonant, causing the tides of the ocean to approach maximum energy levels. Over the next 50 million years, the tides in the North Atlantic and Pacific will resonate and grow stronger. During this time, Asia will divide and create a new sea basin, the study said.

In 100 million years, the Indian Ocean, the Pacific Ocean, and a newly formed Pan-Asian Ocean will see greater resonance and tidal tides. Australia will move north to join the lower half of Asia, as all continents are slowly merging into a single land mass in the northern hemisphere, the new study says.

After 150 million years, the tidal energy begins to sink like that of the earth Land masses form the next supercontinent and the resonance decreases. In 250 million years, the new supercontinent will have formed, resulting in an age of low resonance, resulting in low tidal energy and a largely calm sea.

The new study shows that each tidal maximum lasts at most 50 million years and is not necessarily in phase with the supercontinent cycle.

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Further information:
YES. M. Green et al. Is There a Tectonically Driven Super-Tide Cycle?, Geophysical Research Letters (2018). DOI: 10.1002 / 2017GL076695

Citation in Journal:
Geophysical research letters

provided by:
American Geophysical Union

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