Journey to Mt Sharp - Part 4: Beyond the Kimberley, Sol 634 [May 19, '14] to 706 [Jul 31, '14] Options

[fredk]

Inching forwards on 705:

[anticitizen2]

Hand motion: Scoop open/close - turret 360

Sol 705 anaglyph album of the valley - Stretched

703-705 long baseline of the valley - Stretched

[charborob]

I combined a sol 703 and a sol 705 navcam image (for a wider baseline) into a x-eyed view of Hidden Valley:

(Hard on the eyes for the closer objects.)

[Gerald]

Anaglyph version of a similar stereo:

[jvandriel]

Sol 703.
Hidden Valley in Stereo.

Jan van Driel

[elakdawalla]

With our arrival in Hidden Valley, it's time, I think, for a new topic! Sol 706 and following goes over here.

[CosmicRocker]

Characteristics like the grainy texture, the flaky laminae, and the shiny little specks make this look an awful lot like a micaceous sandstone.

[elakdawalla]

Huh. That is very shiny and very thinly bedded. Fascinating.

[serpens]

We're not in the phyllosilicate rich area. Are you thinking float?

[CosmicRocker]

serpents: When I made that observation I wasn't trying to fit it into any overall context. It was just my initial impression of the rock. When I saw it, it looked very familiar to me, like certain terrestrial sandstones I've seen in the field many times.

You bring up an interesting point, though. I don't know enough about the CRISM measurements to comment about whether that instrument sees all phyllosilicates as the same, or if it can distinguish between the clay mineral group of phyllosilicates and the mica group of phyllosilicates. I think it can discriminate, but I am not sure. Hopefully someone who understands the CRISM data better will comment.

[elakdawalla]

One key point is that there has to be a significant amount of it present for it to even show up in CRISM measurements. It depends on which mineral you're talking about -- some are easier to detect than others -- but I don't think it can detect less than 5% by weight of pretty much any mineral, averaged over an entire CRISM pixel. So you need meters-wide outcrops that have fairly abundant mineral in order for CRISM to detect it.

[jvandriel]

Sol 705
4 MASTCAM R images Debayered, sharpened and stitched.

Jan van Driel

[CosmicRocker]

Good point, Emily, but I would have to suspect that for CRISM detection limits, a quantity like weight % has less relevance than the % areal coverage of the mineral in question. In this case, if we assume that my speculation about the bright specs being flakes of some mica mineral like muscovite is correct, their areal coverage on the surface of the rock is the important variable. Such speculated mica flakes would seemingly comprise less than 5% of the rock by weight, but may cover 20% or more of the outcrop's surface.

[serpens]

So the key variables are surface coverage for an exposed outcrop and the area exposed. Even with oversampling as at Cape
York processing was limited to 5 m/pixel. A huge achievement but exceedingly manpower intensive and I guess only viable for specific, high value targets. Still doesn't answer the question though as to whether CRISM can differentiate between clay mineral and mica groups of phyllosilicates.