(ORDO NEWS) — Data from the New Horizons automatic station confirmed that Pluto’s Mounts Wright and Piccara are indeed the result of cryovolcanism, and not erosion or normal uplift.
It is assumed that several large subsurface sources of cryomagma participated in their creation, and Pluto itself retained heat in its depths longer than previously thought. The article was published in the journal Nature Communications.
The surface of Pluto, the largest object in the Kuiper Belt, shows a very diverse morphology, which suggests that it has been subjected to intense and constant renewal through endogenous and exogenous processes.
It is assumed that the outer layer of the dwarf planet, about 300 kilometers thick, is rich in water ice, and a water ocean may still exist at the base of the ice shell.
The typical surface temperature of Pluto is 35-60 Kelvin, under such conditions, pure water ice should form immobile bedrock, but impurities of ammonia or salts can reduce the melting point of ice. In addition, the melting point of nitrogen ice (63 kelvin) allows it to be more dynamic than water ice, such as flowing slowly.
Another important process associated with ice and capable of influencing the relief of Pluto is considered to be cryovolcanism.
Previously, in images taken by the New Horizons automatic station, scientists have already found candidates for the largest cryovolcanoes in the solar system. However, it is not known when they were active, and what are the features of the course of cryovolcanism on Pluto.
A team of planetary scientists led by Kelsi Singer of the Southwest Research Institute has published the results of an analysis of New Horizons images of Pluto, which refer to a region of suspected cryovolcanic landscapes southwest of the Sputnik Plain. Scientists wanted to study the mechanisms that formed this area and date it.
The most noticeable structures in the cryovolcanic region were large uplifts separated by wide depressions. Two of them, similar to volcanoes, with deep central depressions, received the designations Mount Wright (Wright Mons) and Mount Piccard (Piccard Mons).
The height of Mount Wright reaches 4-5 kilometers, and the width is 150 kilometers, Mount Piccara – 7 and 225 kilometers, respectively. The estimated volume of the main part of Mount Wright is 2.4×104 cubic kilometers, which is similar to the Mauna Loa volcano on Earth.
The central depression of Mount Wright has a diameter of 40-50 kilometers and an approximate depth of 4 kilometers. The central depression of Mount Piccara is larger than that of Mount Wright and has a more rounded or “U” profile.
It does not look like the calderas of terrestrial or Martian volcanoes, and its walls have a lumpy structure, as well as external borders.
The slopes of Mount Wright and much of the surrounding landscape, including the nearby highlands, have an undulating and/or bumpy structure, with wave sizes varying from a few kilometers to 20 kilometers across.
Images of Mount Wright (a) and its environs (b, c). Below (d) is a topographic profile of the area
Distribution of various ices and substances in the area of Mount Wright
Scientists did not find obvious signs of directed flows that could be erupted by cryovolcanoes, obvious traces of explosive volcanism or local sources of eruptions in the images, however, they came to the conclusion that the central depressions could not be formed due to the usual collapse of mountain peaks, and traces of cryovolcanism could be erased from time.
The rarity of craters on Mount Wright indicates its relatively young age, with an upper limit of 1–2 billion years. The surface contains nitrogen, methane, and water ice, as well as dark organic matter represented by tholins.
The researchers concluded that the observed uplifts were formed as a result of the deposition of matter on the surface of the planet through cryovolcanism and are not remnants of mountain erosion or structures created by uplift.
Geological features in the Mount Wright region are morphologically unlike any other regions of Pluto, and also have very little in common with most landscapes on other bodies in the solar system.
It is assumed that there was a sequential mechanism for the formation of all large uplifts and depressions, during which several subsurface sources of cryolava were involved, pouring out a total of more than a thousand cubic kilometers of matter, and some uplifts could merge together. The existence of such large sources of cryovolcanism suggests that
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