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Mars once had oceans of liquid hot magma

red planet Mars

New mineral discoveries on Mars indicate the red planet may have taken far longer to cool down than previously thought (Source: NASA/MGS)

Lighter side Mars once had oceans of liquid hot magma, according to new research by two separate science teams.

The studies, reported in the journal Nature Geoscience, mean the red planet may have taken longer to cool down than previously thought.

Both teams used data from NASA's Mars Reconnaissance Orbiter, to detect significant deposits of light-coloured feldspar minerals, known as plagioclases.

These are commonly only found at two locations in the solar system, the upper continental crust on Earth, and as nearly pure plagioclase rocks called anorthosites in the lunar highlands.

Plagioclases form by crystallising on the surface of magma lakes, out of the lighter silica and feldspar minerals left behind after denser iron-rich material has already settled out to form basalts.

This process is thought to have occurred primarily through plate tectonics and volcanic hotpots on Earth, and through primordial magma oceans, early in the geologic history of the Moon.

Mars, Venus and Mercury were all believed to be exclusively covered by dark, dense, iron rich, basalts which hasn't undergone significant magmatic evolution, similar to Earth's oceanic crust.

This had led scientists to think plate tectonics didn't play a major role in the early geological history of the red planet.

Orbital data

However John Carter and Francois Poulet of the European Southern Observatory, detected eight separate locations with spectral signatures of plagioclase-rich rocks in the Mars Reconnaissance Orbiter data.

"These are found over the southern highlands with a cluster in the northern Hellas region," Carter and Pouldet write.

"The anorthosite exposures are found in the rims of four, 50 to 70-kilometre large craters, as well as in the southern and northern rim of the 140-kilometre large Holden crater."

A second team of scientists led by Dr James Wray of the Georgia Institute of Technology found significant deposits at Xanthe Terra, the large Martian volcano Syrtis Major, and Noachis Terra, which features exposed crater floor bedrock.

"Here, we describe one large region and two smaller locations where felsic materials have been identified," write Wray and colleagues.

"Such feldspar-rich rocks were not anticipated on Mars."

The discovery suggests that similar feldspar minerals identified previously at NASA's Mars Curiosity Rover's landing site in Gale Crater is not an isolated occurrence, and could reflect more widespread magmatic processes on the red planet.

More evidence needed

This is tantalising evidence that the early evolution of the Martian surface and crust is far more complicated than thought, according to planetary scientist, Dr Simon O'Toole of the Australian Astronomical Observatory.

"Maybe our picture of Mars is incomplete, we need to reassess what we think happened in the past, and look for more evidence of this kind of material to get a better global picture," says O'Toole.

"It's a hint that things may not be as they seem, and the early evolution of magma on Mars was different to what we expected, when we just believed the crust was mostly basalt."

If the pooling of magma on Mars was a longer process, materials would crystallize out at different times providing more mineral diversity.

"Seeing these feldspar deposits does suggest that this process took more time," says O'Toole.

Tags: planets-and-asteroids, geology