Massive remote-controlled machines are poised to brave extreme elements to launch an underwater gold rush Man landed on the Moon in 1969, but it would be nearly another decade before we discovered a remarkably alien world right here on Earth. In 1977, a group of geologists sent an unmanned submersible vehicle thousands of metres down to the seafloor off the coast of the Galápagos Islands. They were searching for proof of plate tectonics, the theory that the Earth’s crust not only shifted, but was perpetually consumed and reborn at volcanically active seams. What they found at the bottom of the ocean would revolutionise both geology and biology. In the middle of a vast, featureless desert they discovered otherworldly rock towers, some measuring 30 metres (98 feet) in height, each of them teeming with previously unseen life forms, including snails the size of a fist, tubeworms measuring three metres (9.8 feet) long, paper-white crabs, purple octopi and swarms of shrimp. The fuel for this explosion of life was the boiling-hot fluid spewing from the
038 | How It Works
top of each tower. Rich with minerals, it supported thriving colonies of bacteria, which in turn provided nutrients to increasingly more complex deep-sea life. Geologists labelled these deepwater seams ‘hydrothermal vents’, and thousands more would be located atop every undersea fault line from the Pacific’s ‘Ring of Fire’ to the MidAtlantic Ridge. When scientists analysed samples of rock taken from hydrothermal vents, they found unique chemical and mineral properties. The large rock towers were mostly pyrite – an iron sulphide – and other sulphidedominant rocks. Trapped in these sulphides were high quantities of metallic elements like copper, zinc, and even gold and silver. Why exactly are hydrothermal vents so packed with valuable minerals? It has to do with heat and pressure. The pressure on the deep ocean floor is 160 times greater than at sea level. This forces seawater downward through cracks and seams in the floor. In volcanically
active areas, that water comes into contact with shallow reservoirs of magma, heating it to hundreds of degrees and triggering chemical reactions that strip the seawater of oxygen, magnesium and other elements. As the super-heated seawater percolates toward the surface, its acidity leeches minerals like copper, zinc and iron from surrounding rock. When the hot, mineral-laced water flows out into the deep ocean, it meets surrounding seawater that’s oxygen-rich and nearly freezing cold. The clash of these two extremes triggers another series of chemical reactions in which valuable minerals precipitate out of solution and solidify to form metal-rich towers. The mining industry has known about this deep-sea treasure for decades, but the cost and technical difficulty of digging a mile deep has been daunting. Previous efforts to harvest manganese nodules – potato-sized nickel balls, copper and rare minerals – from the deep ocean floor proved financially disastrous.
WorldMags.net
WWW.HOWITWORKSDAILY.COM
General
Medical
Entertainment
Gadgets
TECHNOLOGY
Domestic
Communication
Engineering
Electronics
Computing
categories explained
WorldMags.net
