The planet Earth provides countless amounts of natural resources, but not everything is found everywhere. And, the locations on Earth where specific types of resources are found tell scientists a great deal about the planet's history. The locations in which humans have found diamonds tells a very interesting story about the movement of landmasses over hundreds of millions of years.
Learn about the diamond and Pangea connection, and how diamonds provide evidence of continental drifts. Find out why certain gems and other valuable resources are found where they are, today, and why they are not found in other places on Earth. And, discover how diamonds act like a time-capsule, allowing scientists a glimpse into the planet's distant past.
DIAMONDS AND PANGEA: HOW DIAMONDS GOT WHERE THEY ARE ON THE EARTH
The most widely accepted theory on diamond formation suggests that diamonds are a result of conditions present around 3 billion years ago. But, this theory only takes into account the types of diamonds the end up in your wedding ring. In 1990, diamonds were discovered in Australia that challenged the standard theory of diamond creation, because of what scientists found inside the diamonds.
Not only do these diamonds contain rare minerals only present about 300 million years ago, but they also present evidence suggesting that these diamonds were formed much deeper in the earth's mantle than typical diamonds. Diamonds are extremely hard, which makes them a great time capsule for elements present too far below the surface of the earth for humans to test. But, how did these diamonds from the deep get up to the surface for us to find?
WHAT ARE GEOLOGIC SUPERCONTINENTS?
A supercontinent is a geologic convergence of the Earth's continental masses, forming a single mass of land. Over the Earth's roughly 4-billion year history, multiple supercontinents have formed and unformed – the youngest of which, Pangea, existed around 300 million years ago. For many years, scientists accepted the theory of continental drift and dismissed the theory of plate tectonics in describing the movement of landmasses.
By the mid-1970s, scientists put together a conclusive map of the oceans' geologic floor, proving the validity of plate tectonic theory. According to the theory of geologic plate tectonics, the earth's crust consists of several dozen plates with defined boundaries. When these plates converge, separation occurs at the divergent boundaries which result in rifts opening.
Meanwhile, underneath the crust, the mantel is churning magma like a convection oven. The Earth's core produces superheated molten rock in the lower mantle, which rises like the oil in a lava lamp, displacing the cooler magma at the upper mantle. This convection heating cycle, all the while is building-up pressure that escapes through the rifts formed by tectonic plate movements.
The pressure from the mantle releases in the form of super-hot geysers of water and seeping magma that solidifies as basalt, forming the crust of a new landmass. But what does this have to do with diamonds?
THE CONNECTION BETWEEN SUPERCONTINENTS AND DIAMONDS
Diamonds form under intense pressure and heat – over a long period. The conditions for diamonds to form are not present at sea-level on the earth's surface. They are present underground, in the earth's upper mantle.
But, the upper mantle of the Earth is over 100 miles beneath the crust – far too deep for human excavation. But, you can buy a diamond for your wedding ring, so how did it get all the way up here? They had to travel to the surface of the earth, somehow.
As tectonic plates converge and split apart, these plates carry masses of land across the world. And, every once in a while, all the masses converge together, forming a supercontinent. And, when they break apart again, it creates the perfect conditions for the type of vehicle that brings diamonds from deep below the earth to the surface.
Kimberlite is a special kind of eruption that has not taken place for hundreds of millions of years since Pangea was splitting apart to form the continental structure as we know it today. As the plate tectonics shifted the Pangea landmass apart, it opened up kimberlite veins. Within only a few hours, these huge eruptions blast through the upper mantle, carrying diamonds with it through the magma.
As Pangea split apart, causing kimberlite eruptions, diamonds were violently brought to the crust. But, these locations were in the process of splitting apart, taking the diamonds with them. Thanks to the cooling of the earth's crust around the time of Pangea, tectonic plates were moving faster, creating the perfect conditions for kimberlites. Scientists estimate that these kimberlites were most active between 250 and 50 million years ago, coinciding directly with the break-up of Pangea.
WHAT DOES IT HAVE TO DO WITH WHERE DIAMONDS ARE FOUND TODAY?
One of the pieces of evidence for the supercontinent theory is the location of gemological resources found on Earth. Look at the Eastern coast of South America, and the Western coast of Africa, in the Gulf of Guinea. You can almost match up the coasts like a jigsaw puzzle.
This could be a mere coincidence, except for the evidence of like-resources. If you matched up the coast-lines like puzzle pieces, a correlation emerges between the types of gemstones you find. For example, Sierra Leone and Venezuela would fit next to each other, and they both feature extensive natural diamond reserves.
Supercontinent theory explains this occurrence. The means of travel for diamonds to become accessible by humans is kimberlite magma eruptions. These eruptions were last seen on Earth when Pangea was breaking-apart around 250 million years ago. So, it stands to reason that the presence of diamonds supports the theory that the continents were once a single mass of land, and is, in fact, the intricate factor in why diamonds are where they are on Earth, today.
Pangea is only the most recent supercontinent formation in the planet's history. Who knows what treasures are hidden in the buried places of the Earth, waiting to be discovered. Talk to a jeweler to find out more about rare and fascinating gems for jewelry.