Geomorphology of Gale Crater, Rock on! Options

[Greg Malone]

Nice little berry to the right of Paul's image. I make it around 8mm diameter and it wouldn't be (visually) out of place in Opportunity's domain.

Looks good enough to have on my breakfast cereal. More seriously, it looks somewhat out of place, but it's a small frame so can't see context. Will find the source image and see what's up.

LATER:
That individual berry-looking object is pretty unique in that immediate area, though there appear to be fragments of similar material nearby in same frame.

While scanning for similar objects in the immediate area on 1553, I did spot this little gem:

Sol 1553 13:12 Site 59/3004 1553ML0079770020604748E01_DXXX

[serpens]

...While scanning for similar objects in the immediate area on 1553, I did spot this little gem:.....

The thing is that if these items are extremely resistant to erosion as seems the case then they could have been emplaced at any level of the kilometres of material that overlaid the current surface.

[Gladstoner]

While scanning for similar objects in the immediate area on 1553, I did spot this little gem:

Stony-iron meteorite?

[HSchirmer]

Swaying towards mud-cracks, yesterday I was convinced these were fractures
[attachment=40555:1555MLcontext.jpg]

Yep, looks like mudcracks, but what's really interesting is the variation in polygon size,
there are small .5 cm polygons and medium 2-3 cm polygons and what seem to be 10 cm polygons.

That suggests a very interesting interplay between the available water, the available sediment, and depth.

image is from Columbia University's earth sciences page about basin filling
https://www.ldeo.columbia.edu/~polsen/nbcp/breakupintro.html


The thick deposits of mudstone made of thin sheets of sun dried mud is paradoxical when you think about it...
Shouldn't a crater fill up with deep lake sediments, then shallow lake, then mud, then sand?

It does raise a neat question, involving faults and geology...
On earth, you get thick deposits of shallow water sediments in extensional basins;
when a half-graben opens up, the land drops slowly, so it starts shallow and stays shallow,
in contrast a crater, should start deep, then gets shallower as it fills in.

http://www.lpi.usra.edu/meetings/lpsc2013/pdf/3106.pdf

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[serpens]

The thick deposits of mudstone made of thin sheets of sun dried mud is paradoxical when you think about it...
Shouldn't a crater fill up with deep lake sediments, then shallow lake, then mud, then sand?
http://www.lpi.usra.edu/meetings/lpsc2013/pdf/3106.pdf

It would be reasonable to expect that the water availability in the Gale lake would vary as would the amount of available sediment, particularly airfall. But this very thin sheet of cracked material does seem to be an anomaly and difficult to reconcile to dessication. Chemcam should reveal something about the makeup of the sheet as it could be possible that these cracks formed sub aqueous in a thin, possibly localised layer of clay rich sediment. Subsequent settling of underlying sediment causing the cracking would explain the variation in shape and size.

[HSchirmer]

It would be reasonable to expect that the water availability in the Gale lake would vary as would the amount of available sediment, particularly airfall.

I really find the juxtapositions interesting.
Surface precipitation might weather clays, but IS need to move sediment, as in peace vallis.
Ground water might weather clays, but IS probably needed for later mineral veins.

https://www.youtube.com/watch?v=xq65TVKDZXs...utu.be&t=11
Gives a really excellent over view of the issues.

Well, if you've got a valley network, availability of water, and sediment are a bit easier to estimate...

Mineralogy and fluvial history of the watersheds of Gale, Knobel, and Sharp craters:
A regional context for the Mars Science Laboratory Curiosity's exploration
Bethany L. Ehlmann, Jennifer Buz

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[wildespace]

Cury losing a marble http://mars.nasa.gov/msl/multimedia/raw/?r...DXXX&s=1555

Any idea what is this spherical object?

[PDP8E]

Hematite? (aka Squyers' blueberries)

[Guest_Steve5304_*]

Hematite? (aka Squyers' blueberries)

To big...process may be similiar but material is probably different.... Don't think we have all the pieces to the puzzle I hope curl does some sciene on that. We passed two others that looked identical on sol 937, 1185, in different sorts of terrain. Pretty strange formation it would be about the size of a marble.

[HSchirmer]

To big...process may be similiar but material is probably different.
...
Pretty strange formation it would be about the size of a marble.

Well, it looks very similar in size to the low grade copper concretions that occur along the US east coast.
Triassic mudstones + igneous intrusions = marble sized ore concretions, usually copper, silver, gold, arsenic.
In my experience, they're usually within about 1 km of the igneous contact.
When the contact is is folded, (scallop shell) instead of flat (clam shell)
they mudstone ores seem to occur more in the peaks (anticlines).

You can see concretions in situ and some spherical voids where others weathered out.

US penny for scale.

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[Guest_Steve5304_*]

Well, it looks very similar in size to the low grade copper concretions that occur along the US east coast.
Triassic mudstones + igneous intrusions = marble sized ore concretions, usually copper, silver, gold, arsenic.
In my experience, they're usually within about 1 km of the igneous contact.
When the contact is is folded, (scallop shell) instead of flat (clam shell)
they mudstone ores seem to occur more in the peaks (anticlines).

You can see concretions in situ and some spherical voids where others weathered out.

US penny for scale.

Thank you for that.


Not to sound like a jerk but i think we should run this thing over and take the chemcam see what it really is.Somebody from nasa is reading i hope!

[serpens]

After the exhaustive work to identify the provenance of Opportunity's berries there is a tendency to consider small spherical objects seen on Mars as concretions. This particular example is isolated so if it is a concretion then transport was involved. However we cannot rule out other causes such as an impact artefact, molten material with a reasonably high ferric component that assumed a spherical shape and cooled in flight, possibly quenched by fall into water. Note Greg Malone's post #810, page 54 on 22 December.

[Guest_Steve5304_*]

After the exhaustive work to identify the provenance of Opportunity's berries there is a tendency to consider small spherical objects seen on Mars as concretions. This particular example is isolated so if it is a concretion then transport was involved. However we cannot rule out other causes such as an impact artefact, molten material with a reasonably high ferric component that assumed a spherical shape and cooled in flight, possibly quenched by fall into water. Note Greg Malone's post #810, page 54 on 22 December.

If that was formed by water it would not be on the surface..it would be below I would think. That had to have broken off or out in the last 100,000 years. Again...I would think but

[HSchirmer]

If that was formed by water it would not be on the surface..it would be below I would think. That had to have broken off or out in the last 100,000 years. Again...I would think but

Eh, remember that there would be a cycle that repeats thousands or millions of times:
dry lake bed, playa, shallow lake, deep lake, shallow lake, playa - dry lake
The dry to wet cycle is nicknamed a van-houten cycle, in the best studied mudstone basins on earth, one cycle is ~20k years, and about 1 meter thick.
Expect you'd have something similar on mars - gale probably went from lake to dry lake and back many times,
based on orbit and eccentricity. there could be "wet" areas both above and below
[what appear to be] the current mud flats.

Yes, there is a tendency to consider small spherical things on mars as concretions,
however, we're looking at fractured mudstones, and experience on earth shows that
fluids moving through cracked mudstones are good at making concretions.
They're common in earth mudstones, so it's acceptable to expect they're common on mars as well...

[serpens]

We have to climb around another hundred metres of Murray formation mudstone and sixty metres or more above that to the hematite ridge. Nicolas Steno's principle of lateral continuity holds that this strata would have originally covered Curiosity's current position, requiring significant water influence over a long period of time. As an aside, the more I look at the hematite ridge the more I wonder whether it could be an inverted bed of what was a reasonably well oxidised stream.