Is the Earth's nucleus rust?

The following article comes from WeChat public account: Sina Explor, the author scientifically explores

Cat Eagle Rock in Arizona Monument Valley. The red of the rock comes from iron oxide minerals. Recent experiments show that iron oxides may also be formed under the surface of the earth, even at the junction of the dartuct nuclear and lower mantles.

When the dive belt carries the deep into the mantle, it may "corrode" the iron outer nuclear of the earth, forming huge oxygen exchange. After that, these oxygen will return to the atmosphere.

The iron on the surface of the earth, whether it is a simple nail or a strong beam, is oxidized when it is exposed to humid air or oxygen -containing water. The reddish -brown product of this reaction is rust and can be composed of various forms of iron -containing iron oxide and iron oxide. In the dry climate zone in the southwest of the United States, and the red rocks found in many other places are the same iron oxide minerals -red iron ore; in a humid environment, iron ore like red iron ore will be weathering Iron -alkali oxides -needle iron ore (FEO (OH)).

Deep in the earth, to be precise, a large amount of melting iron forms the earth's foreign nuclear in 2,900 kilometers below the surface of the earth. So, will the foreign nuclear rust?

Recent Forms of iron oxide-iron hydroxide, the structure is the same as pyrite (called pyrite (OH)). In other words, the oxidation reactions in these experiments will indeed form high -pressure iron rust.

If the rust does exist at the junction of the foreign nucleus and the mantle (the nuclear-mantle boundary, referred to as CMB, also known as the Gudenburg interface), then scientists may need to update their views on the earth and their historical views. These iron rust can reveal the deep water circulation of the lower mantle and the mysterious origin of the ultra -low -speed region (ULVZS). The ultra -low -speed zone is a small and thinner (not more than 50 kilometer) area above the core of the earth fluid, and the speed of the earthquake waves is significantly reduced here. These iron rust may also explain the oxidation incident (GOE) and the NTD oxidation incident (NOE). 540 million years ago, the free oxygen in the atmosphere reached the current level.

But how do we know whether the Gudenburg interface has been rusty?

The red rocks on the surface of the earth mainly come from oxidized red iron and needle iron ore. The rust-rust sediment that may exist on the ground-nuclear-mantle boundary (Gudenbao interface) below 2900 kilometers on the earth may consist of iron-oxide-hydroxide minerals with pyrine-like structures. This rust substance can explain the ultra -low -speed region (ULVZ) found in the earthquake data. The detection threshold in the ultra -low -speed area reflects the resolution of the current seismic section scan.

Earthquake characteristics at the junction of mantle-mantle

Although it is not yet impossible to mine minerals under the Gudenburg interface, we can use other methods to test. If the ground nucleus will rust over time, a layer of rust may have been accumulated on the Gudenburg interface, which can show certain earthquake characteristics.

Laboratory studies have shown that the nucleus' iron oxide-hydroxide rust (ie Feo (OH) X, of which X is the value of 0 to 1) may cause the seismic horizontal wave (VS) and longitudinal wave (VP) speed to pass significantly decreased significantly. It is like the rocks (or partial melting) in the ultra -low -speed area. In fact, compared with the average seismic wave speed as a depth function in the preliminary reference of the preliminary reference to the Earth model, the ground nuclear rust can reduce the horizontal wave and longitudinal wave speed by 44%and 23%, respectively. If the thickness of the ground nuclear iron rust exceeds 3 to 5 kilometers, the huge earthquake -lowering speed reduction will make it recognize in the earthquake layer imaging.

The difficulty is that the earthquake abnormalities in the ultra -low -speed area are caused by the ground nuclear iron rust, or it is caused by other reasons. For example, some melting that occurs at the bottom of the lower mantle is generally considered to cause the ultra -low speed zone, and this may also cause a decrease in seismic wave speed caused by ground nuclear rust.

Theoretically, scientists should be able to scan the earthquake fault to distinguish the ground nuclear rust and partial melting of the Gudenburg interface. Earthquake fault scanning is usually generated through the process of mathematical countermeasures. The process will match the calculated seismic waveform with the observed waveforms. The counterattack process needs to determine the possible mathematical solution of the fitting data, and then select a "best" solution from these solutions according to other considerations.

Each possible mathematical solution corresponds to a set of physical properties related to the materials involved, but there are obvious differences of model parameters, such as the relative differences between the horizontal waves, vertical waves and density of rust materials, and the average value of the mantle around the material.

These differences may change the contents of the material in the mantle, but each material usually shows the characteristic value range (ΔLNVS: ΔLNVP) of the micro -pairing of horizontal waves and longitudinal waves, which can be used to distinguish different materials in the seismic scan. According to mineral physics experiments, the lower limit of this ratio is 1.2: 1 for all possible materials that explain the source of ultra -low -speed regions, and the upper limit is 4.5: 1. In this range, the ratio of the ground nuclear iron rust (pyrine ore (OH) X) is between 1.6: 1 and 2: 1, which is different from other materials.

Earthquake wave speed ratio range of different materials

Evidence of rust origin

So far, seismologists have been sampled in the 60%of the Gudenbao interface to find an ultra -low -speed zone and have determined nearly 50 earthquake waves. Represents the ultra -low -speed area. Most of these areas are coupled with the low -cut speed (LLSVPS) at the bottom of the mantle. ΔLNVS: ΔLNVP is about 3: 1, indicating that there is a partial melting.

However, some of them are located at the edge or external area of ​​LLSVP below the Pacific Ocean, and their best fitting ratio is about 2: 1. For example, a group of ultra -low -speed regions located in the northern border of the Pacific LLSVP (about 9 degrees north latitude, 151 degrees west), and a group of ultra -low -speed regions below the northern Mexico (about 24 degrees north latitude, 104 degrees west). Iron ore FEO (OH) X existing ΔLNVS: ΔLNVP ratio.

A common feature of these ultra -low -speed regions is that they are located in a relatively low temperature on the Gudenburg interface, which is hundreds of hundreds of corfun in the average temperature in LLSVP. Low temperature indicates that these areas are not generated by the melting mechanism. It is worth noting that scientists have determined that the area below the northern part of Mexico is composed of deeply depressed to North America and western Central America about 200 million years ago. Foreign nuclear at the interface of the castle.

Consequence

Scientists believe that Bridgmanite, the main minerals of the mantle under the earth, almost do not have the ability to store water. However, the rust of the ground nuclear may form a large -capacity reservoir in the Gudenburg interface -Feoohx rust may contain water with a weight score of about 7%. Because the ground nuclear iron rust is heavier than the mantle, this reservoir will tend to stay in the Gudenburg interface. Therefore, theoretically, water can be transported and stored outside the ground nucleus, at least in the mantle to the cold area near the relics of the dive section in the mantle, and this is the case before it is unstable.

Whether the water near the nuclear nuclear cores will be circulated back to the surface, and when the return to the surface, it depends to a large extent on the thermal stability of the ground nuclear iron rust. On the basis of experimental work, some scientists claim that Feo (OH) X under the pressure of Gudenbao's interface, the maximum temperature they can withstand is about 2400K. However, under similar pressure, other scientists have observed that the Feo (OH) x can exist from 3100 to 3300K. However, no matter how much the Feo (OH) X can withstand the maximum temperature, when the local nuclear rust migrates to the area where the flow of the Gudenbao interface is more hot with the mantle, it is likely to be decomposed into red iron ore, water and oxygen. This process provides possible explanations for the oxidation history of the earth.

Geology, isotopes and chemical evidence show that during the Taikoo universe, most or all of the earth's atmosphere are in a state of hypoxia. After the Taikoo Hang, the molecular oxygen entered the atmosphere for the first time during the period of about 2.4 billion years ago. The second main rising period of the oxygen content in the atmosphere was the ancient oxidation incident of the new Yuan Dynasty, which occurred about 750 million years ago, making its concentration close to today's level.

Scientists are still not sure about the reasons behind these oxidation events. One possible explanation for the oxidation incident is the emergence of cyanobacteria, and cyanobacteria is an early pioneer of plant photosynthesis. The ancient oxidation incident, which occurred nearly 2 billion years later, was attributed to the rapid increase in marine photosynthesis and the growth of the optical cycle (that is, longer sunshine time).

However, these explanations are far from impeccable. For example, in addition to the lack of time for the occurrence of large oxidation incidents and the occurrence of cyanobacteria on the earth, several studies have shown that after a large increase in oxygen in the atmospheric oxidation incident, it may subsequently fall to a lower level and continue After millions of years. So far, there is no convincing evidence based on the interpretation of cyanobacteria.

In addition, although scientists generally believe that the oxidation incident of large oxidation is only slightly improved compared with the new Yuan ancient oxidation incident, but in laboratory research, through analysis of the optical cycle of microorganisms, its photosynthetic community and chemistry The synthetic community has a competitive relationship -the impact of the output of net oxygen, and they have obtained a contradictory result. During the ancient oxidation incident in the new Yuan, the longer sunlight did not cause these microorganisms to produce more oxygen; experiments showed that during the ancient oxidation incident of the New Yuan, the oxygen increased (from 21 hours to 24 hours) Increases may only be half of the period of oxidation (increase to 21 hours).

Therefore, the changes attributed to the length of the cyanoscopy and the light cycle cannot provide a complete or consistent explanation of the increase in the atmospheric oxygen content during the oxidation incident or the ancient oxidation incident during the ancient oxidation incident, and we cannot rule out other mechanisms of the origin of these events.

The ground nuclear rust (FEO (OH) 0.7) may be formed when encountering a relatively low -temperature dive section with a relatively low -temperature mineral containing minerals. Under the influence of the rust flowing out of the low-temperature area, it will migrate along the nucleus-mantle boundary to the hot area at the root of the mantle column, and it becomes unstable there.

Dive, migration, convection, eruption

For decades, researchers have not found solid evidence to prove when the structure of the earth sector began. However, some recent studies have shown that the dive effect began to bring water -containing minerals deep into the mantle in the mantle 3.3 billion years ago. Experimental studies have shown that the aqueous minerals in the dive section can transport water to the Gudenburg interface. If this is the case, the first ancient rock sector may rust in contact with the ground nuclear. The ground nuclear iron rust may gradually accumulate in the Gudenburg interface, forming an ultra -low -speed area. Driven by the mantle convection, this pile of rust rusted from the cold dive area at the top of the melting foreign nuclear nuclear, and gradually heated up. When it reached the hot area where the mantle column was rooted, it might become very unstable. Just as a typical volcanic outbreak, the temperature -driven ground -iron rust decomposition may cause the intermittent outbreak of the surface oxygen. Compared with the gradual increased oxygen of cyanobacteria, such an outbreak of the release of oxygen may be far faster than the reaction and consumption of the surface environment, resulting in the rapid rise of atmospheric oxygen levels, and then decreased.

Compared with the duration of surface magma eruption, the accumulation and migration of large rust stacks may take longer. In fact, some formed rust piles may not reach the temperature that is sufficient to cause decomposition, and the negative buoyant of the deep mantle around them will keep it under the Gudenburg interface. Geological records show that the surface of the earth was completely covered by the ocean until 3.2 billion years ago. Water can be stored in the form of the surface of the earth and the form of ground iron rust in the deep mantle, which may promote the emergence of the Taikoo -Zhou continent, although the surface, terrain changes, and the growth of the buoyantic continent driven by the sector are also available. contribute.

Potential paradigm changes

Each of us can see that the iron surface on the earth will rust, but unfortunately, no one can directly prove that the core of the liquid iron below 2900 kilometers on the surface of the earth will also occur similarly. However, continuous research will help eliminate all kinds of uncertainty and answer some key questions, such as whether the ground nuclear rust is related to the oxidation incident and the ancient oxidation incident of the new Yuan Dynasty.

In particular, we need more laboratory experiments to accurately determine the thermal stability and component stability limit when the ground nuclear rust meets the balance when the melting iron is balanced under the interface conditions of Gudenbao. For example, we need to study the balance of ground nuclear iron rust and liquid iron at high pressure and high temperature. Other studies can test the heat stability of rust under high pressure. These experiments are challenging, but the laser heating is currently feasible for the experimental ability of the top of the anvil.

In addition, we need to do additional work to determine when to start, especially when to start "wetlinking", to be brought to the depths of the earth. Earth chemical evidence shows that wet leaning did not begin until 2.25 billion years ago instead of 3.3 billion years ago. The wet dive at this late may challenge the ground nuclear rust as a hypothesis for the origin of the oxidation incident.

In addition, whether the mantle is involved in a layer -shaped circulation (a separate convection unit in the upper and lower mantles), a mantra flow or a certain mixed form of the two, these problems still need to be clarified. If the mantle prevails, the dive section will not enter the lower mantle. Therefore, whether it is a whole mantle or mixed -stream, the dive section and the water -containing minerals they carry must exist in order to reach the Gudenburg interface and cause potential foreign nuclear rust.

If we can put together a complete puzzle, then the rust of the foreign nuclear is likely to be a huge internal oxygen generator on the earth -perhaps the next large atmospheric oxidation event is about to occur. This event may cause various problems, including the impact of future environment, climate and residentiality. In the short term, confirming that the Earth's foreign nuclear rust will change our understanding of the deep inside of the earth, and predict how the deep internal Earth will fundamentally affect the environment and life activities on the surface of the earth.

This article is reproduced from WeChat public account: Sina Exploration (ID: sineScience) Author: scientific exploration

Reprinted content only represents the author's point of view

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It does not represent the high energy office of the Chinese Academy of Sciences

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