Great valley found on Mercury

Date:

Share post:

Scientists have discovered a new large valley on Mercury that may be the first evidence of buckling of the planet’s outer silicate shell in response to global contraction. The researchers discovered the valley using a new high-resolution topographic map of part of Mercury’s southern hemisphere created by stereo images from NASA’s MESSENGER spacecraft. The findings were reported in a new study published in Geophysical Research Letters, a journal of the American Geophysical Union.

Great valley found on Mercury
A high-resolution digital elevation model derived from stereo images obtained by NASA’s MESSENGER 
spacecraft has revealed Mercury’s great valley shown here in this 3D perspective view 
[Credit: NASA/Johns Hopkins University Applied Physics Laboratory/
Carnegie Institution of Washington/DLR/Smithsonian Institution]

The most likely explanation for Mercury’s Great Valley is buckling of the planet’s lithosphere — its crust and upper mantle — in response to global contraction, according to the study’s authors. Earth’s lithosphere is broken up into many tectonic plates, but Mercury’s lithosphere consists of just one plate. Cooling of Mercury’s interior caused the planet’s single plate to contract and bend. Where contractional forces are greatest, crustal rocks are thrust upward while an emerging valley floor sags downward.

“There are examples of lithospheric buckling on Earth involving both oceanic and continental plates, but this may be the first evidence of lithospheric buckling on Mercury,” said Thomas R. Watters, senior scientist at the Center for Earth and Planetary Studies at the Smithsonian’s National Air and Space Museum in Washington, D.C., and lead author of the new study.

The valley is about 400 kilometers (250 miles) wide with its floor as much as 3 kilometers (2 miles) below the surrounding terrain. The valley is more than 1,000 kilometers (600 miles) long and extends into the Rembrandt basin, one of the largest and youngest impact basins on Mercury.

The valley is bound by two large fault scarps — steps on the planet’s surface where one side of a fault has moved vertically with respect to the other. Mercury’s contraction caused the fault scarps bounding the Great Valley to become so large they essentially became cliffs. The elevation of the valley floor is far below the terrain surrounding the mountainous faults scarps, which suggests the valley floor was lowered by the same mechanism that formed the scarps themselves, according to the study authors.

“Unlike Earth’s Great Rift Valley in East Africa, Mercury’s Great Valley is not caused by the pulling apart of lithospheric plates due to plate tectonics; it is the result of the global contraction of a shrinking one-plate planet,” Watters said. “Even though you might expect lithospheric buckling on a one-plate planet that is contracting, it is still a surprise when you find that it’s formed a great valley that includes the largest fault scarp and one of the largest impact basins on Mercury.”

Source: American Geophysical Union [November 16, 2016]

ADVERTISEMENT

spot_img

Related articles

Gaelic inscription found on medieval Spanish church

An ancient inscription discovered on a 14th century church in Spain's Galicia region has been identified as Gaelic;...

Origins of ‘The Hoff’ crab revealed

The history of a new type of crab, nicknamed 'The Hoff' because of its hairy chest, which lives...

How and where the bodies were buried: an ancient UAE mystery revealed

The bodies in the grave unearthed by Sophie Mery’s archaeological team in Umm Al Quwain may be the...

Investigating the Pickles Reef mystery in the Florida Keys

On shallow Pickles Reef, three and a half miles off the shore of Key Largo, the sun lit...

Previously unknown global ecological disaster discovered

There have been several mass extinctions in the history of Earth with adverse consequences for the environment. Researchers...

Medieval iron hoard found in Slovakia

Archaeologists found an iron treasure while doing research in Bojná near Topoľčany. The Slavic inhabitants of the region...

Roman graves uncovered in Canterbury

Archaeologists have uncovered an ancient burial ground in Kent where around a hundred people were laid to rest.  The...

Medieval brewery used by monks discovered in England

A medieval brewery has been discovered by archaeologists along the route of Lincoln Eastern Bypass. Network Archaeology Ltd,...