Mound near lunar south pole formed by unique volcanic process

October 15, 2015 by Kevin Stacey
Volcanic processes touched off by a massive impact appear to have created Mafic Mound, a strange feature near the moon's south pole. Credit: NASA/Goddard/Arizona State University

A giant mound near the Moon's south pole appears to be a volcanic structure unlike any other found on the lunar surface, according to new research by Brown University geologists.

The formation, known as Mafic Mound, stands about 800 meters tall and 75 kilometers across, smack in the middle of a giant crater known as the South Pole-Aitken Basin. This new study suggests that the mound is the result of a unique kind of volcanic activity set in motion by the colossal impact that formed the basin.

"If the scenarios that we lay out for its formation are correct, it could represent a totally new volcanic process that's never been seen before," said Daniel Moriarty, a Ph.D. student in Brown's Department of Earth, Environmental and Planetary Sciences and the study's lead author.

The research has been accepted for publication in Geophysical Research Letters, a publication of the American Geophysical Union, and is available online.

Mafic Mound (mafic is a term for rocks rich in minerals such as pyroxene and olivine) was first discovered in the 1990s by Carle Pieters, a planetary geologist at Brown and Moriarty's adviser. What makes it curious, other than its substantial size, is the fact that it has a different mineralogical composition than the surrounding rock. The mound is rich in high-calcium pyroxene, whereas the surrounding rock is low-calcium.

A topographic view of the South Pole-Aitken Basin. Reds are high; blues are low. Mafic Mound, (the reddish area in the center) stands 800 meters above the surrounding surface. Credit: NASA/Goddard/MIT/Brown

"This unusual structure at the very center of the basin begs the question: What is this thing, and might it be related to the basin formation process?" Moriarty said.

To investigate that, Moriarty and Pieters looked at a rich suite of data from multiple lunar exploration missions. They used detailed mineralogical data from the Moon Mineralogy Mapper, which flew aboard India's Chandrayaan-1 spacecraft. NASA's Lunar Orbiter Laser Altimeter provided precise topographic data, and data from the GRAIL mission characterized gravitational anomalies in the region.

Those combined datasets suggested that Mafic Mound was created by one of two unique volcanic processes set in motion by the giant South Pole-Aitken impact. An impact of that size would have created a cauldron of melted rock as much as 50 kilometers deep, some researchers think. As that sheet of impact melt cooled and crystalized, it would have shrunk. As it did, still-molten material in the middle of the melt sheet may have been squeezed out the top like toothpaste from a tube. Eventually, that erupted material may have formed the mound.

Such a process could explain the mound's strange mineralogy. Models of how the South Pole-Aitken melt sheet may have crystalized suggest that the erupting material should be rich in high-calcium pyroxene, which is consistent with the observed mineralogy of the mound.

Another scenario that fits the data involves possible melting of the Moon's mantle shortly after the South Pole-Aitken impact. The impact would have blasted tons of rock out of the basin, creating a low-gravity region. The lower gravity condition could have enabled the center of the basin to rebound upward. Such upward movement would have caused partial melting of mantle material, which could have erupted to form the mound.

These scenarios make for a strong fit to those very detailed datasets, Moriarty said. And if either is true, it would represent a unique process on . Moriarty said a sample return mission to the South Pole Aitken Basin would be a great way to try to verify the results. The basin has long been an interesting mission target for lunar scientists.

"It's the largest confirmed impact structure in the solar system and has shaped many aspects of the evolution of the Moon," Moriarty said. "So a big topic in lunar science is studying this basin and the effects it had on the geology of the Moon through time."

A sample return mission to the could bring back bits of lunar mantle, the composition of which is still not fully understood. A returned sample could also put a firm date on when the impact occurred, which could be used as a standard to date other features on the surface.

And in light of this work, a sample could also help to shed light on a unique lunar volcanic process.

Explore further: Ancient crater could hold clues about moon's mantle

More information: Geophysical Research Letters, … 02/2015GL065718/full

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1.5 / 5 (16) Oct 15, 2015

There are more important things to do in space than worry about stupid sample return missions.

For an educated person, your complete lack of vision is disgusting.

The moon needs to be a staging area for resource harvesting and "energy" harvesting (hate that flawed word), and for astronomy and such. Not some spending 200 billion dollars just to bring back 100lbs of rocks. We already did that 6 times before, remember?

If you want to look for resources, you should use seismology and ground pentrating radar, not go pick up some rocks and one or two core samples from your favorite crater.

Imagine if the explorers just sailed to north america and turned to europe repeatedly and did nothing with it; no colonies, no fisheries, no forestry, no crops, just sail back and forth from NA to Europe every 40 years, with maybe a few hundred pounds of sugar to tease the King with once in a while

What an idiotic waste.
3.9 / 5 (21) Oct 15, 2015
And you no doubt should have better things to do than troll here, every goddamned article, first in, demonstrating that all you do is sit there jacking off and spewing crap.

STFU, already.
Oct 15, 2015
This comment has been removed by a moderator.
3.2 / 5 (11) Oct 15, 2015
He needs to go to work for one of (Ras)Putin's troll farms in Moscow. Join the rest of the vile wastes of humanity with no socialization, no respect for themselves, anyone else, or any form of life or the environment, gushing verbal diarrhea wherever serious discussion dare break out.

I'll bet most those losers are legends in their own mind too.

And then we need to nuke the place.
1.3 / 5 (14) Oct 15, 2015
You mean everyone doesn't immediately wonder reading each article on the site, "But I wonder what the oxygen thief thinks?"

What an idiotic waste.

Yes, you are. Please do something about it. Better yet, take the paper bag off your head anonymous coward. Your parents have some accounting to do.

Actually I gave my real name and address on here a few days ago.

I got banned whenever I used my real name here, and I got banned from "physicsforums" for proving the definition of "energy" is flawed, and I got banned from "physforums" for showing how to make the basic concept model for a fully hybrid AI which would use both an electronic neural net and a classical computer.

The assholes don't want to learn. they don't want any alternate perspective.

He literally told me that questioning Relativity was in itself grounds for IP ban...automatically.

That's not science. That's idiocy. And the FOOL has a degree and is a professor.

Piss off.
1.3 / 5 (14) Oct 15, 2015
History will record people like THAT as the true fools and cranks, in the long term.

They are the ones hindering progress, not me.

You are the ones making personal attacks, not me.

People here are the ones defending murderers, such as muslims, not me.

Where the hell either of you lying idiots got the idea that I that I don't respect life I wouldn't know.

Yeah, I have a right to call you a lying idiot when you're a lying idiot.

Oh yes, we must all be held accountable, but not to you, fool.

I'll be held accountable to God, and I'll have been wrong some of the time and right others, and I'm prepared to deal with that when it happens.
1.6 / 5 (13) Oct 15, 2015
And then of course I live in a country where our political parties are both brain dead a fuck and never do anythign but waste money and campaign for the next election. Hell, half the representatives and senators skip out on even voting.

I have a president who is a panzy and knows nothing about strategy or tactics, and fires every general who did at least know something half-assed right.

The hell are we in Syria anyway, but if we're going to oppose the "Assad Regime" then why in God's name don't we just drop one of those 20k "MOAB" bombs directly on his dick and vaporize his ass, instead of getting tens of thousands of other people killed?

Because we have dumbass politicians instead of leaders in this hellhole of a failed-state democracy.
1.6 / 5 (13) Oct 15, 2015
If I was a commanding officer in the Air Force operating in Syria...I mean seriously...our incompetent military can accidentally hit a hospital with a bomb and you're gonna tell me we can't "accidentally" nail Assad himself with a bomb?

You know, not exactly pretty, but the colonists in the war of independence defeated Britain in part because one of their primary strategies was to aim at officers first.

That's what we should be doing in Syria. Just hit the government builds. Don't "fight" the military. That's not how you win a war. You win a war by killing the governing party....

"fighting" is stupid in warfare.

Stupid. Stupid. clueless.
3.3 / 5 (14) Oct 15, 2015
What the hell does "returners" mean anyway? Is it a Zionist reference? You don't seem the type that would know spirituality from a buffalo turd.

It's amazing how people that yell the exact.same.word over.and.over.and.over again never notice that it applies best to themselves.
2.7 / 5 (7) Oct 15, 2015
And love the sound of their own voice. Don't know where the correlation with morbid obesity comes from, but you see if often enough.
1.9 / 5 (9) Oct 15, 2015
What the hell does "returners" mean anyway? Is it a Zionist reference? You don't seem the type that would know spirituality from a buffalo turd.

It's amazing how people that yell the exact.same.word over.and.over.and.over again never notice that it applies best to themselves.

No. It's a reference to a group of rebels who are opposing an evil empire in a certain video game I used to play.


If you can't see that the Palestinians are the evil ones, then you need serious help anyway. Now they got their teens mass stabbing little kids in the back.

And you defend this? Damn you're warped.

God bless those Israelis who shot those murderers down. I hope they go through with the plan to bury those dogs in secret, so their families can't make some kind of islamic jihad hero out of them.

Generations of Palestinian suicide bombers and gunmen attacking diners and buses full of unarmed people.

Rot in hell. Hope there's something worse than hell for them.
2 / 5 (8) Oct 15, 2015
Then they had the audacity to edit videos to try to make it look like it was the soldier's fault for shooting the murdering punks, and putting it on social media. Good thing the Israelis had access to the full video and were able to broadcast it on news networks.

Your little satanic murdering Palestinian friends should leave Israel's land and go join their satanic cousins, isis, in Iraq.
Mark Thomas
5 / 5 (7) Oct 16, 2015
On a much different note, perhaps a similar volcanic process involving water is at work on Occator Crater on Ceres. Buried, pressurized (and salty?) water leaks out on occasion.
Whydening Gyre
5 / 5 (4) Oct 16, 2015
On a much different note, perhaps a similar volcanic process involving water is at work on Occator Crater on Ceres. Buried, pressurized (and salty?) water leaks out on occasion.

Thank you, Mark.
Out of all the comments on this article, THIS was the ONLY on topic one...
Any one care to guess why?
1 / 5 (3) Oct 16, 2015
Just the thought of the magnitude of impacts involved in forming planets and moons makes me giddy for the day when we can optically render such collisions in other star systems. I can't wait for the first image of a planet and moon colliding to hit the media. I will stand up, cheer, and yell "SKLABLOOOOOOOM!"

Science demands such noises upon new and amazing discoveries.
2.1 / 5 (7) Oct 17, 2015
Electric discharge is the only explanation that can account for the crater, mound, mafic minerals, and the distribution of the matter without conjuring up some nonsensical geological tube of toothpaste. But it won't stop the plasma deniers from trying.
5 / 5 (5) Oct 17, 2015
Electric discharge is the only explanation that can account for the crater, mound, mafic minerals, and the distribution of the matter without conjuring up some nonsensical geological tube of toothpaste. But it won't stop the plasma deniers from trying.

Great... another of 'those' comments...
Just wondering: what the heck is a "plasma denier"?
3.4 / 5 (5) Oct 22, 2015
Just wondering: what the heck is a "plasma denier"?

Somebody who is scientifically literate enough to require a hypothesis to at least have some sort of evidence, and to make scientific sense, before taking it even remotely seriously. Hence why EU/PC is considered to be a pseudoscience, ranked alongside homeopathy and astrology.

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