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Earth’s “Hot Flash” Responsible for Continental Crust
Analysis of ancient zircon grains finds that many injections of continental crust occurred during a period of time when Earth’s mantle was at its hottest.
One thing we can say for certain is that Earth is an ocean world. But how did it end up with as much continental crust as it did? The most prevailing thought started to look really good once scientists decided that plate tectonics was a thing. (Beth wants me to say [checks notes], “Justice for Alfred Wegener!”) After all, plates dive down under one another in subduction zones, causing the underlying rock to melt and rise through the crust to form volcanoes that create more crust. And as those plates come together, others rift apart and create zones where molten rock rises and again, forms new crust. See Iceland.
Of course, the flipside to the subduction zones is that the rocks that submerge and get heated are also destroyed, so we’re not actually seeing a net gain in the continental crust there or from the rift zones. Additionally, plate tectonics hasn’t always worked this way, which really defies a basic precept of geology that’s what’s past is prologue — meaning we can trace back how things worked in the past by looking at how they work now. It’s just not fair when we…
