Cape York, Landfall! Options

[Phil Stooke]

Quite possibly, but filled with minerals precipitated out of groundwater.

Phil

[walfy]

On the way to the cemented fractures to the north (if that's what they are and if indeed we're going there), this feature could be looked over, circled here in yellow:



Probably just craters, maybe from the same family, or one crater with material sloshed across the middle. Or maybe pits of some other origin?

[stevelu]

or maybe pits of some other origin?

That's where the Morlocks are waiting...

[stevelu]

Or maybe pits of some other origin?

But, a bit more seriously, are we learning enough about all this geology & sometimes acidic H2O percolation to speculate about possible cave-forming processes yet? Other than lava tubes I mean.

[Juramike]

The rocks are sulfates, not carbonates...the acidity of water shouldn't affect dissolution of sulfates.
(Hmmm, maybe I need to think about this one a bit....).

Anyone?

[Juramike]

Geeked out and learned stuff:

Heavy metal sulfates have no pH dependence on solubility at low pH (acid conditions). [http://www.geochem.geos.vt.edu/bgep/pubs/9...mica%20acta.pdf]

General info on mineral weathering (pH dependence about halfway through)
http://home.wlu.edu/~kuehns/Geo311/F09/Weathering4.pdf

Fun facts:
The absorption of high notes in seawater is due to MgSO4 in the ocean. Low notes transmit better. (NaCl has no effect)
http://en.wikipedia.org/wiki/Magnesium_sulfate

The highest hydrated magnesium sulfate known, MgSO4*11H2O is thought to have dissolved away and formed the empty vugs seen in Meridiani Planum.
http://en.wikipedia.org/wiki/Meridianiite

[marsophile]

The rocks are sulfates, not carbonates...the acidity of water shouldn't affect dissolution of sulfates.

A stronger acid will displace a weaker acid. Sulfuric acid is more corrosive, but AFAIK hydrochloric is a stronger acid, so theoretically a hydrochloric acid bath could replace sulfates by chlorides the way sulfuric acid replaces carbonate by sulfates.

[Juramike]

It will be a subtle effect.

Comparison of solubility of CaCO3 vs. CaSO4 on addition of HCl solution:

(pH and solubility): http://www.chemistry.nmsu.edu/studntres/ch...solubility.html

Thus, calcium carbonate is much more soluble in acidic solution, whereas the solubility of calcium sulfate is only slightly affected.

[serpens]

... are we learning enough about all this geology & sometimes acidic H2O percolation to speculate about possible cave-forming processes yet?

I don't think we have seen any evidence of sulphate dissolution in all our time at Meridiani have we? So wouldn't any liquid have been a saturated solution?

[Bill Harris]

Very indirectly and speculatively, Serpens. Some think that the Anatolia features are caused by dissolution of the evaporitic sandstone along joint fractures. No proof, really, but then, no dis-proof.

--Bill

[MoreInput]

For those who just want to have a short illusion of viewing 3d I built a primitive web site with java script, which does the flickering for you.
Just store the attached HTML file to your local disk and open it in your browser. If you click on the button "flicker" the view should permanently switch between left and right picture.
It does a good job on Chrome. On Firefox it seems, that the pics should have been downloaded before into the cache. Doesn't work on IE.

In the two text boxes you copy the URL to the original pancam/navcam/hazcam pictures.
http://marsrover.nasa.gov/gallery/all/1/p/...JYP2585L2M1.JPG
http://marsrover.nasa.gov/gallery/all/1/p/...JYP2585R2M1.JPG

Or use the exploratorium server:
http://qt.exploratorium.edu/mars/opportuni...K3P2591L2M1.JPG
http://qt.exploratorium.edu/mars/opportuni...K3P2591R2M1.JPG

For the NASA server you can also use the HTML url, it will be changed to JPG automatically:
http://marsrover.nasa.gov/gallery/all/1/p/...YP2585R2M1.HTML

Attached File(s)

 flicker.html ( 1.43K ) Number of downloads: 358

 

[centsworth_II]

The rocks are sulfates, not carbonates...

Or more likely some form of altered basalt. The sulfates that (probably) once covered Cape York are mostly or entirely eroded away.

[Beauford]

The rocks are sulfates, not carbonates...the acidity of water shouldn't affect dissolution of sulfates.
(Hmmm, maybe I need to think about this one a bit....).

Anyone?

Sulfates generally do not exhibit pH dependent solubilities because the sulfate anion is a very weak base. In other words, its very hard to protonate sulfate. Perchlorates, nitrates and halides are also very weak bases, but the solubilities of their metal salts are often high because they are monovalent anions. Sulfides, carbonates and phosphates are often pretty insoluble due to their high charge, but all are also good bases. For sulfides, carbonates and phosphates (for example) exposed to acidic water, a set of simultaneous equilibria involving protonation and dissolution steps are present. If the pH is specified, it's not horribly difficult to solve these simultaneous equilibria for the concentrations of each ionic species, even if multiprotic events occur.

Hoping this doesn't bring back bad memories of college chemistry!

[Matt Lenda]

For those who just want to have a short illusion of viewing 3d I built a primitive web site with java script, which does the flickering for you.
Just store the attached HTML file to your local disk and open it in your browser. If you click on the button "flicker" the view should permanently switch between left and right picture.
It does a good job on Chrome. On Firefox it seems, that the pics should have been downloaded before into the cache. Doesn't work on IE.

In the two text boxes you copy the URL to the original pancam/navcam/hazcam pictures.
http://marsrover.nasa.gov/gallery/all/1/p/...JYP2585L2M1.JPG
http://marsrover.nasa.gov/gallery/all/1/p/...JYP2585R2M1.JPG

Or use the exploratorium server:
http://qt.exploratorium.edu/mars/opportuni...K3P2591L2M1.JPG
http://qt.exploratorium.edu/mars/opportuni...K3P2591R2M1.JPG

For the NASA server you can also use the HTML url, it wil be change to JPG automatically:
http://marsrover.nasa.gov/gallery/all/1/p/...YP2585R2M1.HTML

This is genuinely awesome.

-m

[Explorer1]

Yes, thanks so much!
I remember one flicker gif when Spirit went down Husband hill years ago, but nothing since then. I can never find 3D glasses anywhere and crosseyed is just annoying.