VANCOUVER — For the past four decades, the theory of plate tectonics has remained a fixture in every geologists understanding of how the earth’s crust glides across the planet and subducts beneath the continents. But what if the early Earth, circa 3.2 billion years ago, was just too hot for plate tectonics to work?
A recent study published in the journal Nature has added weight to growing evidence that the Earth’s first continents didn’t form by subduction — the process of ocean crust diving underneath continents, melting and creating a chain of volcanoes. Rather, they may have formed from the partial melting of abnormally thick ocean crusts that developed under the extreme temperature conditions of ancient earth.
All this may be relevant to mineral exploration, considering many companies are exploring in rocks older than 3.2 billion years, looking for orogenic gold and magmatic nickel-copper deposits. Being reminded that the magmatic and tectonic regimes were possibly different back then may help fine-tune their exploration models.
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