Simulation reveals possible cause of Mercury's distinctive features

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Washington, March 18 : Scientists have created numerical simulations of the three-dimensional nature of convection within Mercury's silicate mantle, which might reveal possible cause of the planet's distinctive features.

Scott D. King, professor of geosciences at Virginia Tech, developed the simulation.

The computations were done using the Virginia Tech geoscience department's High-Performance Earth Simulation System, a high-speed, high-capacity 768-core Dell computing cluster.

Patterns of scalloped-edged cliffs or lobate scarps on Mercury's surface are thrust faults that are consistent with the planet shrinking and cooling with time. However, compression occurred in the planet's early history and Mariner 10 images revealed decades ago that lobate scarps are among the youngest features on Mercury.

According to the simulation, loss of heat from the mantle through the crust has played a role in the formation of lobate scarps on Mercury.

Scientists have offered a number of explanations for global contraction on Mercury, such as cooling and core formation, tidal effects due to gravitation interactions with the Sun, impacts, and mantle convection.

"The idea that contraction due to cooling is the cause of these features has been around for a long time and makes a lot of sense," said King. "But the apparent pattern and the orientation of these features is puzzling," he added.

According to King, "I can't really rule out the idea that this is just an artifact of the one hemisphere we have seen and the one camera/sun angle that we have pictures from. But the orientation of these features seems to require something additional, which I think is mantle convection."

King noted that the upwellings from mantle convection on Mercury takes the form of long, linear rolls in distinctive clusters and directionality, rather than a random pattern associated with upthrusts from global compression acting alone.

"The pattern of convection I see in my mercurian convection models is different from Venus, Mars, and Earth because the mantle is so much thinner - or the iron core is so much larger relatively speaking," said King.

"On Venus, Earth, and Mars, the hot material coalesces into cylindrical plumes, not linear sheets. That could influence the tectonics at the surface and the convection within the iron core, which is most likely what is responsible for Mercury's magnetic field," he said.

According to King, "The timing and orientation of these features are controlled by convection and not global contraction."

"Because the model suggests that mantle convection is still active today, gravity and topography data from the Messenger mission may be able to confirm the model," he added.

ANI

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