Jezero Delta Campaign, Sols 414-1000, 21 Apr 2022- 23 Dec 2023 Options

[neo56]

Peaceful sight of the rover's tracks winding across the floor of Jezero crater, imaged on sol 422 by Mastcam-Z Left.

[tau]

Indeed, a very peaceful and beautiful picture. It looks like a romantic painting.

Layered outcrops at the base of Cape Nukshak, seen from a distance of about 6 m on sol 422
1. Supercam Remote Micro-Imager. A very rough grain-size estimate: in the rock about 0.4 to 0.5 mm, dark sand 0.2 to 0.3 mm
2. Mastcam-Z context
3. Mastcam-Z left eye filters 1 to 6 multispectral principal components

[tau]

More layered outcrops at the base of Cape Nukshak in Mastcam-Z images from sol 423
1. Raw image filter 0 (RGB)
2. Left eye filters 1 to 6 multispectral principal components. A few stones have alternating blue/purple layers.
3. Right eye infrared filters 1 to 6 multispectral principal components 1 and 2
4. Anaglyph

[Keltos]

More layered outcrops at the base of Cape Nukshak in Mastcam-Z images from sol 423
1. Raw image filter 0 (RGB)
2. Left eye filters 1 to 6 multispectral principal components. A few stones have alternating blue/purple layers.
3. Right eye infrared filters 1 to 6 multispectral principal components 1 and 2
4. Anaglyph

Tau : any clue as to what minerals the colors represent?

do we have mudstone here ? grain is not visible but the resolution lacks a bit it seems

[neville thompson]

Gigapan - PERSEVERANCE 420-S-W
© NASA/JPL-Caltech/MSSS/ASU/NeV-T

[neville thompson]

Gigapan - PERSEVERANCE 423-N
© NASA/JPL-Caltech/MSSS/ASU/NeV-T

[neo56]

Panorama taken with Navcam Left (my first attempt to this tricky dataset!) on sol 422 at 14:12 LMST.

[tau]

Tau : any clue as to what minerals the colors represent?

Sorry, no clue. The colors are somewhat arbitrary, because the results of the principal components analysis depent on the overall image content and some manual adjustments.
Irrespective of this, radiometrically calibrated multispectral image data are required for mineral determination.
An idea of the calibration and processing pipeline is given by this paper, this paper, and this document.
With radiometrically calibrated data and mineral spectra libraries, it might be possible, see the "Mineralogy" chapter and Fig. 3 in this paper.
The rover has further instruments for elemental and mineral analysis (SuperCam, SHERLOC).

[StargazeInWonder]

I think with PCA, all that you can safely say about two highly contrasting colors is that there is a difference between two things, but there's no definite information about the nature of that difference, and it could easily be some combination of illumination, texture, composition or possibly other things, in any unknown combination.

For example, when you see the color patterns where oil or gasoline and water are on wet pavement, the color differences have absolutely nothing to do with compositional differences.

An image of snow and ice might show considerable variation in color even though every bit of solid present is pure H2O.

Moreover, with the PCA, the contrasts seen across one part of the image are further altered by what happens to be present in other parts of the image.

We may easily be looking at one more or less constant composition of the rocks in these photos with different history of weathering, burial, dust cover, etc.

[neville thompson]

Gigapan - PERSEVERANCE 422-N
© NASA/JPL-Caltech/MSSS/ASU/NeV-T

[Bill Harris]

Very good, Tau. My sense suggests to me that the finely-bedded bluish rocks are silt- or mudstones. Fine particle sizes that remained in suspension and settled away from the early delta. The purplish rocks are a different mineralogy and are somtimes associated with the siltstone units, which may well.be cyclic. Some purplish rocks appear to be coarse grained and may represent rocks that have tumbled down from higher in the section, or may represent cataclysmic flows in the streams or may represent turbidites from the delta. The mineralogical difference may be the result of intense chemical weathering of volcanic rocks in wet basins of the upland that were breached during intense rainfall events and entered the streams as a slug.

--Bill

[serpens]

If you are right that the deposition was fallout in the lake prior to delta formation Bill then couldn't the banded layers reflect variations in oxygenation conditions within the lake? Assuming an abiotic influence, say periodic changes in cloud or ash cover affecting levels of UV at the surface and potentially shallow water.

[tau]

I think with PCA, all that you can safely say about two highly contrasting colors is that there is a difference between two things, but there's no definite information about the nature of that difference, and it could easily be some combination of illumination, texture, composition or possibly other things, in any unknown combination. . . .
Moreover, with the PCA, the contrasts seen across one part of the image are further altered by what happens to be present in other parts of the image.
We may easily be looking at one more or less constant composition of the rocks in these photos with different history of weathering, burial, dust cover, etc.

Thank you, StargazeInWonder, I couldn't explain it better.
Another example with relation to Mars:
A solid piece of crystalline hematite (like the famous "blueberries") is steel gray and may appear blue after PCA transformation.
Hematite powder is red (used as pigment Red ochre).
The nature of the difference here is the different particle size, the mineral is the same.

. . . My sense suggests to me that the finely-bedded bluish rocks are silt- or mudstones. . . .

I had the same impression due to the smooth surfaces and thin layering.
I hesitated to write it down until we get more details (high resolution images, mineral analyses).

[HSchirmer]

Thank you, StargazeInWonder, I couldn't explain it better.
Another example with relation to Mars:
A solid piece of crystalline hematite (like the famous "blueberries") is steel gray and may appear blue after PCA transformation.
Hematite powder is red (used as pigment Red ochre).
The nature of the difference here is the different particle size, the mineral is the same.

I had the same impression due to the smooth surfaces and thin layering.
I hesitated to write it down until we get more details (high resolution images, mineral analyses).

I'll mention again - might want to check the "Newark Basin Coring Project" out of Rutgers-
They were able to correlate orbital orientation to rainfall, correlated to lake depth, such that blueshales are deep-water anoxic,
redshales are shallow water-playa exposed and oxidized.

Some terrestrial basins have tell-tale enrichment of rare-earth elements from the deepest lakestands, I'd be quite curious to see if any of those compounds turn up, or are detectable.

Meanwhile- What's that? Everyone's looking at the silt layers, what's with the 'worm castings?"

Attached thumbnail(s)

 

[tau]

. . . Meanwhile- What's that? Everyone's looking at the silt layers, what's with the 'worm castings?"

A SuperCam image of this little pile would be interesting,
and a SuperCam image of the bumpy surface of this purple rock in the foreground of the sol 423 Mastcam-Z image below.