Mars Had Plate Tectonics

C M Edwards · 2005-11-04 15:56:46

Not sure where to put this, but this looked as good a place as any.

According to this article, Mars appears to have had more Earth-like plate tectonics early in its history, and may still. Old explanations for evidence of polar wandering that suggest its entire crust moved as one piece are probably false. I also saw an article in Discover magazine suggesting that Valles Marineris occurs at a plate boundary - like the Marianas Trench here on Earth, although Valles Marineris appears too close to the edge of the data collection area to tell for certain using their map alone.

If true, that would require no catastrophic flooding for the initial formation of Valles Marineris, only later shaping by water. It would also have profound implications for the distribution of mineral deposits.

Dook · 2005-11-04 18:04:18

I'm not an expert on magnetic fields but it seems to me that the spotty magnetic fields on mars are probably caused by iron ore deposits. Each iron molecule has it's own north and south pole but when connected to another molecule they combine. Put more and more iron molecules together and your magnet grows. Each deposit would have it's own north and south pole so that's why the instruments detected so much flipping.

I'm not sure if the iron ore has to be formed (cooling magma high in iron content) in the presence of a magnetic field. If so maybe mars had one long ago and now we are only seeing what remains of it, large and small magnets across the planet.

RobS · 2005-12-04 02:01:38

Yes, Dook, what you are referring to is called paleomagnetism. When igneous or sedimentary rocks form, small magnetic minerals initially are able to turn and align themselves with the prevailing magnetic field; then the rest of the igneous rock solidifies or the sediments compact and the magnetic particles are locked into place permanently. Scientists can remove a sample from the rock, place it in a machine, and determine the alignment of the magnetic minerals. As a teenage geology student I remember walking around a basaltic mountain with a compass and was amazed by how much ordinary basalt will cause a compass to deviate. One of the satellites currently in Martian orbit, when it was aerobraking, came very close to the surface--sixty miles or less--and was able to detect zones on Mars where all the rocks had their paleomagnetic compasses pointing in the same direction, followed by other zones where all the paleocompasses pointed in the other direction. This indicates Mars used to have a magnetic field and it reversed polarity periodically, just as Earth's does today.

-- RobS

MarsDog · 2005-12-06 01:57:14

http://www.student.oulu.fi/~jkorteni/sp … rface.html

http://www.nasa.gov/centers/goddard/new … lates.html

Recent lava and volcanoes are on top lowlands,
while the magnetic changes are on the bottom highlands.

Which way were the plates drifting ?

sethmckiness · 2005-12-12 19:25:08

I really doubt that the large scale drifts in magnetism have much to do with magnetic based deposits as opposed to large scale rock layers deposited while the pole where aligned in one direction or the other. thats what these maps tend to show, most obvious is in the sea bed which shows beautiful evidence of seafloor spreading. Most large scale mineral deposits that could influence the magnetism of the sensors are not large enough to be of significant resolution to affect the map.

the best example is the mesabi and vermillion iron ranges in Northern Minnesota are both very narrow in width. (I believe less then a mile for both)

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#1 2005-11-04 15:56:46

Re: Mars Had Plate Tectonics

#2 2005-11-04 18:04:18

Re: Mars Had Plate Tectonics

#3 2005-12-04 02:01:38

Re: Mars Had Plate Tectonics

#4 2005-12-06 01:57:14

Re: Mars Had Plate Tectonics

#5 2005-12-12 19:25:08

Re: Mars Had Plate Tectonics

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