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See the last billion years of the Earth’s tectonic plate motion in just 40 seconds



tectonic plates

A map of the Earth̵
7;s current tectonic plate boundaries. Eric Gaba for Wikimedia Commons

The land mass that was Antarctica once set along the equator. Throughout Earth’s history, several supercontinents have broken up and reunited as the Backstreet Boys.

Our current seven continents and five oceans are the result of more than 3 billion years of planetary evolution, the tectonic plates intersecting at the top of the semi-solid radiance of the earth’s core.

But mapping the precise movements of these plates throughout that time is challenging; Existing models are often piecemeal, spanning only a few million years, or focusing on only continental or oceanic changes, not both.

For the first time, a group of geologists has offered an easily digestible look at 1 billion years of plate tectonic motion.

Geoscientists from the University of Sydney spent four years reconstructing how land masses and oceans have changed over the last billion years. As part of a recent study, they animated the changes in the short video below.

The animation shows green continents emptying over the sea, which is represented in white. Ma at the top of the video is geological talk for 1 million – so 1000 Ma is 1 billion years ago. The different color lines represent different types of boundaries between tectonic plates: Blue-purple lines represent divergent boundaries, where the plates split apart; red triangles indicate overlapping boundaries, where the plates move together; and gray-green curves show boundaries of transformation, with the plates sliding sideways past each other.

“These plates move as the fingernails grow, but when a billion years are condensed in 40 seconds, a fascinating dance is revealed,” said Sabin Zahirovic, a geologist at the University of Sydney who co-authored the new study, in a press release. .

To build a better model of the earth’s plates

Pangea kart

A map shows what Pangea looked like 200 million years ago, with tectonic plate boundaries in white. Wikimedia Commons

The Earth formed 4.4 billion years ago, and then cooled enough to form a solid crust with individual plates about 1.2 billion years later.

Today, one can imagine the planet as a chocolate truffle – a viscous center shrouded in a hardened shell. The center consists of a 1800 km thick, semi-solid mantle that surrounds a super-hot core. The top layer – only about 21 miles thick – is the crust, which is fragmented into tectonic plates that fit together.

These plates surf on top of the mantle and move around as warmer, less dense material from deep inside the earth rises toward the crust, and colder, denser material sinks toward the core.

Geologists can put together a picture of what plates were there hundreds of millions of years ago by analyzing what is known as paleomagnetic data. When lava at the junction of two tectonic plates cools, some of the resulting rock contains magnetic minerals that correspond to the direction of the earth’s magnetic poles at the time the rock solidified. Even after the plates containing these rocks have moved, scientists can study the magnetic alignment to analyze where the natural magnets existed on the global map in the past.

Using both paleomagnetics and current tectonic plate data, the study authors were able to create the most thorough map of each plate’s journey from 1 billion years ago to the present day.

midatlantic_mdl_2014_bathy_lrg 2

A map of the Atlantic Ocean floor. NASA Earth Observatory map by Joshua Stevens, using data from Sandwell, D. et al. (2014)

“Simply put, this complete model will help explain how our home, the planet Earth, became habitable for complex creatures,” said Dietmar Müller, co-author of the study, in a press release.

Of course, the puzzle on the continents of the earth has not stopped changing. For example, the Pacific Ocean is shrinking year by year. The Atlantic Ocean, meanwhile, is expanding – pushing America from Africa and Europe.

Read the original article on Business Insider


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