Using information from contained in the rocks on Earth’s surface, my colleagues and I actually have reconstructed the plate tectonics of the planet over the past 1.8 billion years.
It’s the primary time Earth’s geological record has been used like this, looking up to now back in time. This has enabled us to make an attempt at mapping the planet over the past 40 percent of its history, which you’ll see within the animation below.
The work, led by Xianzhi Cao from the Ocean University in China, was recently published within the open-access journal Geoscience Frontiers.
A Beautiful Dance
Mapping our planet through its long history creates a ravishing continental dance—mesmerizing in itself and a piece of natural art.
It starts with the map of the world familiar to everyone. Then India rapidly moves south, followed by parts of Southeast Asia because the past continent of Gondwana forms within the Southern Hemisphere.
Around 200 million years ago (Ma or mega-annum within the reconstruction), when the dinosaurs walked the earth, Gondwana linked with North America, Europe, and northern Asia to form a big supercontinent called Pangaea.
Then, the reconstruction carries on back through time. Pangaea and Gondwana were themselves formed from older plate collisions. As time rolls back, an earlier supercontinent called Rodinia appears. It doesn’t stop here. Rodinia, in turn, is formed by the breakup of a good older supercontinent called Nuna about 1.35 billion years ago.
Why Map Earth’s Past?
Among the many planets within the solar system, Earth is exclusive for having plate tectonics. Its rocky surface is split into fragments (plates) that grind into one another and create mountains or split away and form chasms which can be then crammed with oceans.
Other than causing earthquakes and volcanoes, plate tectonics also pushes up rocks from the deep earth into the heights of mountain ranges. This fashion, elements which were far underground can erode from the rocks and wash into rivers and oceans. From there, living things could make use of those elements.
Amongst these essential elements is phosphorus, which forms the framework of DNA molecules, and molybdenum, which is utilized by organisms to strip nitrogen out of the atmosphere and make proteins and amino acids—constructing blocks of life.
Plate tectonics also exposes rocks that react with carbon dioxide within the atmosphere. Rocks locking up carbon dioxide is the foremost control on Earth’s climate over very long time scales—much, for much longer than the tumultuous climate change we’re liable for today.
A Tool for Understanding Deep Time
Mapping the past plate tectonics of the planet is the primary stage in having the ability to construct an entire digital model of Earth through its history.
Such a model will allow us to check hypotheses about Earth’s past. For instance, why Earth’s climate has passed through extreme “Snowball Earth” fluctuations or why oxygen built up within the atmosphere when it did.
Indeed, it is going to allow us to significantly better understand the feedback between the deep planet and the surface systems of Earth that support life as we realize it.
So Much More to Learn
Modeling our planet’s past is important if we’re to grasp how nutrients became available to power evolution. The first evidence for complex cells with nuclei—like all animal and plant cells—dates to 1.65 billion years ago.
That is near the beginning of this reconstruction and shut to the time the supercontinent Nuna formed. We aim to check whether the mountains that grew on the time of Nuna formation can have provided the weather to power complex cell evolution.
Much of Earth’s life photosynthesizes and liberates oxygen. This links plate tectonics with the chemistry of the atmosphere, and a few of that oxygen dissolves into the oceans. In turn, quite a few critical metals—like copper and cobalt—are more soluble in oxygen-rich water. In certain conditions, these metals are then precipitated out of the answer: In brief, they form ore deposits.
Many metals form within the roots of volcanoes that occur along plate margins. By reconstructing where ancient plate boundaries lay through time, we will higher understand the tectonic geography of the world and assist mineral explorers to find ancient metal-rich rocks now buried under much younger mountains.
On this time of exploration of other worlds within the solar system and beyond, it’s value remembering there’s a lot about our own planet we’re only just starting to glimpse.
There are 4.6 billion years of it to analyze, and the rocks we walk on contain the evidence for a way Earth has modified over this time.
This primary attempt at mapping the last 1.8 billion years of Earth’s history is a breakthrough within the scientific grand challenge to map our world. However it is just that—a primary attempt. The subsequent years will see considerable improvement from the place to begin we now have now made.
The creator would really like to acknowledge this research was largely done by Xianzhi Cao, Sergei Pisarevsky, Nicolas Flament, Derrick Hasterok, Dietmar Muller and Sanzhong Li; as a co-author, he is only one cog within the research network. The creator also acknowledges the numerous students and researchers from the Tectonics and Earth Systems Group at The University of Adelaide and national and international colleagues who did the basic geological work this research is predicated on.