MSL scientific results Options

[TheAnt]

Thank you for posting that one Eutectic, I had already read it, and if I had not been seated safely I could have fallen over in surprise.
Trondheimite type granite found on Mars! I am far from a specialist, many hobby geologists could quite likely teach me things, even so I know this is a major find.

[dvandorn]

Yes! This is an amazing find. Granites are thought to have formed on Earth when hydrated crust (read: seafloor) is subducted during plate tectonics. Now, trondhjemite (and the TTG suite in general) doesn't necessarily show the chemical signatures of having directly re-mixed with mantle material, so finding the stuff on Mars doesn't absolutely prove that Mars had what we would recognize as plate tectonics. It's a pretty sure sign that some crustal subduction of highly hydrated rocks did occur, though, of some type.

Unless, of course, this is an example of a piece of Earth's Archaen crust that was whacked into space by a big impact and transported to Mars, just as Martian meteorites have been found on Earth. That would seem to be less probable than Mars creating its own granites, though, I think.

-the other Doug

[monitorlizard]

Granite (the author uses the term granitoid) rocks were found on Mars by a combination of MGS TES and Mars Odyssey THEMIS data going back to papers from 2004 and 2006 by Bandfield. The locations were in the Syrtis Major region (61.8 Lat,-65.9 E Long and a second location whose description is a bit screwed up in my source). The key paper is:

Bandfield, J.L. Extended surface exposures of granitoid composition in Syrtis Major, Mars. Geophys. Res. Lett. 33, doi:10.1029/2005GL025559, 2006.

Finding granite in Gale Crater would extend the area of extent of granite on Mars, a very welcome discovery. My source was "The Martian Surface" book edited by Jim Bell, which was published in 2008. CRISM may or may not have found additional exposures since then, I don't know. I think thermal infrared works better for finding granite's minerals than CRISM's spectrum, though.

[monitorlizard]

Oops! I completely misread the coordinates of the granitoid exposures in Syrtis Major. The correct description of the location is that there are two exposures contained within a single area that is bounded by a line running from 61.8 to 65.9 degrees East longitude and a line running from 18.4 to 20.5 degrees North latitude. By the way, the total area of exposures with significant concentrations is 19 square kilometers.

Sorry for the screw up.

[Julius]

A paper in Science magazine issued 9th October on paleoclimates and lacustrine environment in gale crater. Don't have link. Do not have free access to it I m afraid!

[Paolo]

A paper in Science magazine issued 9th October on paleoclimates and lacustrine environment in gale crater.

here it is:
Deposition, exhumation, and paleoclimate of an ancient lake deposit, Gale crater, Mars
it's funny... I downloaded it two days ago and I am sure it was in open access!

[Julius]

here it is:
Deposition, exhumation, and paleoclimate of an ancient lake deposit, Gale crater, Mars
it's funny... I downloaded it two days ago and I am sure it was in open access!

Thanks for your effort Paolo but I still don't have access to it for some reason.

[atomoid]

Oops! I completely misread the coordinates of the granitoid exposures in Syrtis Major. The correct description of the location is that there are two exposures contained within a single area that is bounded by a line running from 61.8 to 65.9 degrees East longitude and a line running from 18.4 to 20.5 degrees North latitude. By the way, the total area of exposures with significant concentrations is 19 square kilometers.

Sorry for the screw up.

curious to see if the granite would be positioned relative to Mars' magnetic features perhaps suggesting such subduction zones were positioned according to plate spreading as indicated by remnant fields..? but if i'm reading the coordinates correctly thats around Isidis..

[Julius]

Impressive study providing detailed analysis of different rock stratigraphy along the curiosity traverse from Bradbury to Murray formation. However there is no mention of rock compostion along the way. As far as I know, there had been a puzzle as the rock make up up to now had been largely basaltic in nature. Provided that these sediments had been theorised as being laid down by water, this basaltic composition seems somewhat of a contradiction since water should have altered the basaltic nature of the rock. Any thoughts?

[elakdawalla]

You can download the recent Science paper from the MSL website: http://mars.nasa.gov/msl/mission/science/researchpapers/

[serpens]

curious to see if the granite would be positioned relative to Mars' magnetic features perhaps suggesting such subduction zones were positioned according to plate spreading as indicated by remnant fields..? but if i'm reading the coordinates correctly thats around Isidis..

Impacts can demagnetise any rock having a residual field so the identification of granite near a massive impact feature with little remnant magnetism is not a contradiction. Valles Marineris seems to show evidence of lateral movement which could imply plate tectonics, while the Tharsis Montes could be an ambulatory product similar to the Hawaiian chain. As far as Gale Crater is concerned, Sautter et al (Nature Geoscience 8, 605–609 (2015)) drew attention to the possible correlation between the feldspar-rich light coloured magmatic rocks found by Curiosity and continental crust. Given the extent of cratering the wonder is that any remnants of Mar's magnetic field survived.