Geologists suggest that the mixing of magmatic melts the pockets could cause an explosion a little more than 600 thousand years ago. The canyon walls consist of rhyolite tuff and lava. The crystals in this tuff may contain clues to the conditions of magmatic processes, just before the eruption of Yellowstone.
Map of the known boundaries of the Eruption of Yellowstone
Yellowstone national Park is famous for more than just its hot springs. This area is known in volcanological community to be the site of three super eruptions, the last of which was 631,000 years ago.
During this eruption, approximately 1,000 cubic kilometres of rock, dust and volcanic ash soared into the sky. Shards rained down on the continental United States, encompassing a rough triangle that stretches from the present canadian border to California and Louisiana. In places the ash has reached more than a meter thick.
“If something like this would happen today, it will have disastrous consequences,” said Hannah to Shamlu, a geologist at the school of the University of Arizona . “We want to understand what causes these eruptions, so we can create a system alert. It is the goal of a great mission.”
Now, Shamlu and her co-author think they found the key. Investigating trace elements in the crystals that they found in the remains of the last volcanic super-Eruption of Yellowstone, they could help to determine exactly what caused the eruption.
Just outside Yellowstone national Park, found in the tuff Lava Creek tuff of this type is a thick, multi-colored, layered rocks tuff. Tuffs are igneous rocks formed by volcanic eruptions and debris left after the explosive eruption .
The minerals in these tuffs can tell scientists about the conditions inside the volcano, before it erupted, and identifying these conditions may help to inform the assessment of the current danger as the Yellowstone.
Shamlu and Christy To the consultant at the University of Arizona, was reviewed by two crystals of feldspar that are found in the tuff. These crystals, called Phenocrysts, form as magma slowly cools under the volcano.
These Phenocrysts 1 to 2 mm in diameter, were too large to be formed when hot material hits during the eruption.
Instead, as explained by Shamlu, they grew gradually over time in the magma chamber of Yellowstone, each crystal starting from the core, which is slowly and gradually increased outward, layer by layer. The last layers of Phenocrysts has changed in the surrounding conditions of temperature, pressure and water.
Thus, differences in chemical composition between the core of the Phenocrysts and the successive layers serve as maps of changes in the conditions deep inside the volcano for a long time. Moreover, the outer layers of the Inclusions represent magma that surrounded the crystal right before the Yellowstone eruption.
Thus, analyzing the outer layers, Shamlu and Christie To could collect information that would determine what temperature to track immediately before the massive explosion.
The temperature in the outer layers of Ukreplennye can be computed using a method called feldspar thermometry. The method is based on the fact that some minerals change their composition by known methods, with a change of temperature. Thus, scientists can work backwards from the exact composition of the minerals present in these outer layers to estimate the ambient temperature during the formation of the crystal.
To explore the Duo found the elements that indicate the temperature increase and the increase in the element barium in the magma immediately before eruption. They presented their research on 13 December at the fall meeting of the American geophysical Union in San Francisco, California.
In order to test them layer by analyzing the level of temperature and chemical composition, used a program that simulates the composition of the crystal is changed depending on the temperature, pressure and water content in a magma chamber. They suggested that the magma had the same composition as the tuff Lava Creek. Their results and model match, but pointed to the low content of water to the magma chamber. In contrast, the tuff had 5% water by weight, 5 times more than the tuff Lava Creek.
Low water content is surprising, Shamlu explained, because the water and steam creates pressure, which can cause rashes. But Shamlu said that the history of Ukreplenii from hotter temperatures and more barium in the magma chamber just before the eruption suggests a possible cause of the explosion: a mixture of adjacent pockets of magma, calls the event injection. “There are several ways to trigger the eruption, but as of now, we see the mixing of adjacent pockets of magma,” she said.
Magma, or molten rock, which exists in the earth’s crust, can also reach the Earth’s surface. Because it is less dense than surrounding rocks, magma can move up through cracks in the earth’s crust, but when its movement is cornered, it pools into magma chambers. These cameras are enhanced by the igneous injection, when hot material from deeper volcanic reservoirs will be absorbed into smaller units. This injection of hot material just before the eruption can explain the temperature increase recorded in the phenocrysts.
But the presence of barium in the phenocrysts is the Smoking gun, told Shamlu. “Barium does not like to be in the crystal. He likes to hang out in the melt, so that tells us that barium must have been introduced from another source. “Duo believes that this source represents a deeper reservoir within the volcano.
Eric Christiansen, a volcanologist from Brigham young University in Provo, Utah, who was not involved with the study were skeptical of the use of Shamlu software modeling and believes that this type of modeling is not as reliable as a real experiment with real rocks. However, he argued that her work and her analysis is correct. She has an interesting data trace elements barium, the latest addition to the camera, which suggests that this caused the eruption.
The public is always afraid of the truth told Shamlu. To know the trigger mechanism of the eruption is only the first step, according to Chamlou. The next step is understanding how much time-days, months, even years, these changes can be made before the eruption that produced the tuff Lava Creek.
Such information can help Shamlu, and other researchers to correctly read the signs of volcanic activity in Yellowstone and create a model for predicting future super-Eruption of Yellowstone.
