Does Mars have Plate Tectonic Activity? - Does Mars have Plate Tectonic Activity?

Ian · 2004-01-25 20:48:59

Does anyone know whether or not mars has plate tectonic activity or whether or not mars had it in the past?

Shaun Barrett · 2004-01-26 01:20:46

Hi Ian!
As usual, Mars is ambiguous in its reply to your question! There's evidence, of sorts, that there may have been an era of tectonic plate activity early in Mars' history, but apparently not everybody thinks the evidence is conclusive.

As you probably know, the most vivid evidence of tectonic plate movement on Earth is found either side of the expanding Atlantic sea-floor. New crust is being created in the Mid-Atlantic Ridge as two plates move apart and magma wells up from below. The new crust assumes the magnetic properties of Earth's field at the time of its formation, which can change over geological time with the frequent magnetic pole reversals which occur. The result is alternating stripes of ocean floor, one magnetised with north where it is now and the neighbouring stripe magnetised in the opposite direction because it was formed when Antarctica was magnetic north.

Anyhow, similar stripes have been found in the ancient cratered highlands of the martian southern hemisphere.
For a neat little description of what was found there, check out [http://www.exn.ca/Stories/1999/04/30/56.asp]THIS SITE.

Ian · 2004-01-26 16:19:17

Shaun. Do you think that in the past, when there might have been liquid water on mars, that there was a lot of plate tectonic activity and caused the continents on mars "If there are or were any" to move away from each other? Do you know where these continents might be on mars and if they moved away from each other in the past, are they still doing so now?

Shaun Barrett · 2004-01-26 18:40:25

I honestly wish I knew, Ian.
To the best of my knowledge, that large area of magnetic stripes in the southern hemisphere is about the only evidence of tectonic activity on Mars; it stands alone. As the article says, even that evidence is questioned by some geologists because it's not impossible for simple crustal stretching to cause a similar effect - although it seems to me a little bit like the experts are casting around for ideas when they say that. I don't recall anyone finding magnetic stripes anywhere here on Earth that were put down to expansion and contraction of the crust, though I could be wrong.

Some people seem to think that even Earth would have no tectonic plate movement were it not for the fact that the proto-Earth was slammed into by a Mars-size object about 4.5 billion years ago. That collision, which formed the Moon, also stripped away a lot of the thick crust which Earth had accumulated up to that point, leaving the remnant which today is seen as the continental plates. These continental plates are substantially thicker than the oceanic plates and drift around like slag on molten metal.
If Earth had never been struck by that planetoid, so it's been theorised, it would have retained its planetwide thick crust - almost like one huge planet-encompassing plate. All relative movement then would have been impossible and, for all we know, Earth may have followed the same evolutionary path as Venus. Current hypotheses about Venus suggest that, without tectonics, internal heat builds up and causes a catastrophic convulsion of volcanism maybe every 700 million years, which completely resurfaces the whole planet with lava.

Looking at Mars, it's possible to imagine the southern highlands as an analogy for Earth's continental plates, while the lower northern plains could be taken as the equivalent of Earth's thinner-crusted oceanic plates.
But tectonic activity, if it ever really happened on Mars, should have left other clues like fold mountains. The Himalayas and the Alps are examples of such mountains, formed by one plate crashing into another. The Andes have arisen (literally! ) because the South American continental plate is moving westward as the Atlantic expands and is riding up over the South Pacific oceanic plate. The oceanic plate is being subducted down into the mantle and remelted, causing a chain of volcanoes in the Andean mountains as the subducting crustal rock heats and expands below them.
A geologist could doubtless tell you about many more tell-tale signs of tectonic activity but I guess you get the point! (Sorry, but I do tend to ramble a little bit )

As far as I know, there's nothing else on Mars (apart from those stripes) which points to plate tectonics, although any evidence from early in Mars' history may have been erased by subsequent impact cratering.
Even the sequence of cratering on Mars has been called into question by at least one or two researchers, which potentially throws our tentative dating of geological events there into doubt!
I suppose the bottom line is that we simply haven't enough data about Mars for a definitive answer and much of the data we do have seems contradictory and therefore uncertain!

So many questions, so few answers!

JasonF · 2004-01-27 00:43:53

Some people seem to think that even Earth would have no tectonic plate movement were it not for the fact that the proto-Earth was slammed into by a Mars-size object about 4.5 billion years ago. That collision, which formed the Moon, also stripped away a lot of the thick crust which Earth had accumulated up to that point, leaving the remnant which today is seen as the continental plates. These continental plates are substantially thicker than the oceanic plates and drift around like slag on molten metal.

Now here's a thought. Would life be possible on Earth without that collision? The geochemical cycle plays a big role in the biosphere. Where would we be without it?

Shaun Barrett · 2004-01-27 02:07:10

This is a question which has made me less optimistic about the number of 'other Earths' out there.
That collision may well be responsible for enabling the tectonic activity which recycles CO2, preventing its complete sequestering in carbonate rocks.
The same tectonic activity allows Earth to 'let off steam', so to speak, in a reasonably controlled manner, avoiding the kind of planetwide violent crustal upheavals which afflict Venus. It's hard to imagine terrestrial life surviving the kind of total resurfacing Venus experiences every so often.

The collision produced the Moon, which was instrumental in slowing Earth's rotation to its present rate by tidal gravitational interactions. Calculations indicate a 5 hour day (2.5 hours daylight, 2.5 hours darkness) just after the Moon's formation but we don't know how fast Earth was rotating before the impact.
The Moon provided us with daily tides and the intertidal zones (between the high and low tide mark) have been credited with helping life to originate (a controversial point) and, much later, with helping marine creatures to adapt to living on land.
The Moon also stabilises Earth's axis of rotation, keeping it within a certain small range and thus preventing radical changes in our overall climate. By contrast, computer models have shown Mars' axial tilt to be prone to large and chaotic changes over geological time, varying up to 60 degrees in some simulations!

With all the apparent benefits which ensued from that cosmic collision, and knowing that the chances of such an encounter producing just the right circumstances are probably very low, it does make you wonder whether a long-lived and diverse biosphere is actually an extremely rare thing.
We may not be alone in the universe, but it may be a long long way between Earths! We may be living on a particularly precious jewel.
???

JasonF · 2004-01-27 06:11:46

Thanks Shaun. I had suspected a lot of that information, but never really heard it all brought together. Any probes planned that look at the seismology of Mars? I know we had seismographs on some moon missions, but have hear nothing about Mars.

Ian · 2004-01-27 13:28:17

I think that it's a good idea to send a probe to mars which could measure the seismology of mars. I wonder if some special sensor could be made for such a probe that could have software that would analyze the data and send it back to earth for future analyses by humans.

Shaun Barrett · 2004-01-27 18:34:26

I don't think any seismographic experimentation has ever been done successfully on Mars to date.
The Viking landers each carried a seismometer. Unfortunately the one on Viking I failed to send back any information, while the other one functioned for a year and only detected one seismic wave.
Apparently this scant information was insufficient to form any hypotheses about Mars' internal structure or activity.

I agree it would be interesting to get some marsquake data and I suppose there are people working on the idea 'as we speak'!

Ian · 2004-01-28 16:46:31

Are there ways to measure seismic activity using a laser interferometer from orbit over mars?

Ian · 2004-01-28 16:54:07

I've heard that people are trying to measure gravitational waves using laser interferometers. I think that they get a lot of interference from the earth's gravity and planes that fly over them and other stuff too.

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#1 2004-01-25 20:48:59

Re: Does Mars have Plate Tectonic Activity? - Does Mars have Plate Tectonic Activity?

#2 2004-01-26 01:20:46

Re: Does Mars have Plate Tectonic Activity? - Does Mars have Plate Tectonic Activity?

#3 2004-01-26 16:19:17

Re: Does Mars have Plate Tectonic Activity? - Does Mars have Plate Tectonic Activity?

#4 2004-01-26 18:40:25

Re: Does Mars have Plate Tectonic Activity? - Does Mars have Plate Tectonic Activity?

#5 2004-01-27 00:43:53

Re: Does Mars have Plate Tectonic Activity? - Does Mars have Plate Tectonic Activity?

#6 2004-01-27 02:07:10

Re: Does Mars have Plate Tectonic Activity? - Does Mars have Plate Tectonic Activity?

#7 2004-01-27 06:11:46

Re: Does Mars have Plate Tectonic Activity? - Does Mars have Plate Tectonic Activity?

#8 2004-01-27 13:28:17

Re: Does Mars have Plate Tectonic Activity? - Does Mars have Plate Tectonic Activity?

#9 2004-01-27 18:34:26

Re: Does Mars have Plate Tectonic Activity? - Does Mars have Plate Tectonic Activity?

#10 2004-01-28 16:46:31

Re: Does Mars have Plate Tectonic Activity? - Does Mars have Plate Tectonic Activity?

#11 2004-01-28 16:54:07

Re: Does Mars have Plate Tectonic Activity? - Does Mars have Plate Tectonic Activity?

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