While thousands of people have visited the highest point of the planet, Everest, only three have descended to the bottom of the Mariana Trench. This is the least explored place on Earth, there are many mysteries around it. Last week, geologists found that over a million years, 79 million tons of water penetrated through the fault at the bottom of the depression into the bowels of the Earth.
What happened to her after that is unknown. "Hi-tech" talks about the geological structure of the lowest point on the planet and the strange processes that take place at its bottom.
Without sun rays and under colossal pressure
The Mariana Trench is not a vertical abyss. It is a crescent-shaped trench, stretching for 2,500 km east of the Philippines and west of Guam, USA. The deepest point of the depression, the Challenger Deep, is 11 km from the surface of the Pacific Ocean. Everest, if it were at the bottom of the depression, would not have been 2, 1 km to sea level.
Map of the Mariana Trench.
The Mariana Trench (as the trench is also called) is part of a global network of troughs that cross the seabed and were formed as a result of ancient geological events. They arise when two tectonic plates collide, when one layer sinks under the other and goes into the Earth's mantle.
The underwater trench was discovered by the British research ship Challenger during the first global oceanographic expedition. In 1875, scientists tried to measure the depth with a diplot - a rope with a weight tied to it and meter markings. The rope was only enough for 4,475 fathoms (8,367 m). Almost a hundred years later, the Challenger II returned to the Mariana Trench with an echo sounder and set the current depth value of 10,994 m.
The bottom of the Mariana Trench is hidden in eternal darkness - the sun's rays do not penetrate to such a depth. The temperature is only a few degrees above zero - and close to the freezing point. The pressure in the Challenger Abyss is 108.6 MPa, which is about 1,072 times the normal atmospheric pressure at sea level. This is five times the pressure that is created when a bullet hits a bulletproof object and is approximately equal to the pressure inside a polyethylene synthesis reactor. But people found a way to get to the bottom.
Man at the bottom
The first people to visit the Challenger Abyss were the American military Jacques Piccard and Don Walsh. In 1960, in the bathyscaphe "Trieste", they descended to 10,918 m in five hours. At this mark, the researchers spent 20 minutes and saw almost nothing because of the silt clouds raised by the apparatus. Except for the flounder fish, which was hit by the spotlight. Having life under such high pressure was a major discovery for the mission.
Before Piccard and Walsh, scientists believed that fish could not live in the Mariana Trench. The pressure in it is so great that calcium can exist only in liquid form. This means that the bones of the vertebrates must literally dissolve. No bones, no fish. But nature has shown scientists that they are wrong: living organisms are able to adapt even to such unbearable conditions.
Many living organisms in the Challenger Abyss were discovered by the Deepsea Challenger bathyscaphe, on which, in 2012, director James Cameron went down to the bottom of the Mariana Trench. In soil samples taken by the apparatus, scientists have found 200 species of invertebrates, and at the bottom of the depression - strange translucent shrimp and crabs.
At a depth of 8 thousand meters, the bathyscaphe discovered the deepest fish - a new representative of the species of lipar or sea slugs.The fish's head resembles a dog's, and its body is very thin and elastic - while moving, it resembles a translucent napkin that is carried by the current.
A few hundred meters below, there are giant ten-centimeter amoebas called xenophyophores. These organisms show amazing resistance to several elements and chemicals like mercury, uranium and lead that would kill other animals or humans in minutes.
Scientists believe there are many more species at depth, awaiting discovery. In addition, it is still not clear how such microorganisms - extremophiles - can survive in such extreme conditions.
The answer to this question will lead to a breakthrough in biomedicine and biotechnology and will help to understand how life began on Earth. For example, researchers from the University of Hawaii believe that thermal mud volcanoes near the depression may have provided the conditions for the survival of the first organisms on the planet.
Volcanoes at the bottom of the Mariana Trench.
What is the rift?
The depression owes its depth to the fracture of two tectonic plates - the Pacific layer goes under the Filipino, forming a deep trench. The regions in which such geological events have occurred are called the subduction zone.
Each plate is nearly 100 km thick, and the fault is at least 700 km deep from the lowest point of the Challenger Abyss. “This is an iceberg. The man was not even at the top - 11 is nothing compared to 700 hiding at depth. The Mariana Trench is the borderline between the limits of human knowledge and a reality that is inaccessible to humans,”says geophysicist Robert Stern of the University of Texas.
Slabs at the bottom of the Mariana Trench.
Scientists suggest that water in large volumes enters the Earth's mantle through the subduction zone - the rocks at the boundaries of the faults act like sponges, absorbing water and transporting it into the bowels of the planet. As a result, the substance is found at a depth of 20 to 100 km below the seabed.
Geologists from the University of Washington found that over the past million years, more than 79 million tons of water got into the bowels of the earth through the junction - this is 4.3 times more than previous estimates.
The main question is what happens to the water in the bowels. It is believed that volcanoes close the water cycle, returning water to the atmosphere as water vapor during eruptions. This theory has been supported by previous measurements of the volumes of water entering the mantle. Volcanoes emitted into the atmosphere approximately equal to the absorbed volume.
A new study refutes this theory - calculations indicate that the Earth absorbs more water than it returns. And this is really strange - given that the level of the World Ocean over the past few hundred years not only has not decreased, but has grown by several centimeters.
A possible solution is to reject the theory of equal bandwidth of all subduction zones on Earth. Conditions in the Mariana Trench are likely to be more extreme than in other parts of the planet, and more water seeps through the rift in the Challenger Abyss.
“Does the amount of water depend on the structural features of the subduction zone, for example, on the bending angle of the plates? We assume that similar faults exist in Alaska and Latin America, but so far man has not been able to find a deeper structure than the Mariana Trench,”added lead author Doug Vines.
The water hidden in the bowels of the Earth is not the only mystery of the Mariana Trench. The US National Oceanic and Atmospheric Administration (NOAA) calls the region an amusement park for geologists.
This is the only place on the planet where carbon dioxide exists in liquid form. It is ejected by several submarine volcanoes located outside the Okinawa Trough near Taiwan.
At a depth of 414 m in the Mariana Trench, there is the Daikoku Volcano, which is a lake of pure sulfur in liquid form, which constantly boils at a temperature of 187 ° C.6 km below there are geothermal springs that emit water at a temperature of 450 ° C. But this water does not boil - the process is hindered by the pressure exerted by a 6, 5-kilometer water column.
The ocean floor has been less studied by man today than the moon. Probably, scientists will be able to detect faults deeper than the Mariana Trench, or at least investigate its structure and features.