Crossing the Dunes at Murray Buttes, Sites 54-62, Sols 1353-1659, May 28 2016-Apr 6 2017 Options

[Gerald]

Out of the hip, I could offer four more hypotheses:
-1- In the upper left corner of the image at midnightplanets you refrenced, there appear to be remnants of an overlying (greyish) rock layer. This layer seems to be more resistant to erosion than the underlying (reddish) layer. The smaller grains may be other relics of the overlying layer.
-2- The embedded grains may be sparse brecciated clusts in a sedimentary siltstone.
-3- We are near hematite ridge. Depending of the composition of the embedded material, we might see first embedded iron ore fragments.
-4- Embedded tektites of a meteorite; recently we have seen likely iron meteorites.

[PaulH51]

Thank you all for sharing your hypotheses I now have some more reading to do...

Here is the sol 1614 3x3 R-MastCam mosaic of the layered block "Aroostook River" mentioned in the 1614-1616 USGS mission update.

I cropped the edges a little and tweaked the jpeg compression to bring the file size within the upload limits.

Edit: The block is ~53 cm wide
Full resolution version LINK

[HSchirmer]

Out of the hip, I could offer four more hypotheses:
-1- In the upper left corner of the image at midnightplanets you refrenced, there appear to be remnants of an overlying (greyish) rock layer. This layer seems to be more resistant to erosion than the underlying (reddish) layer. The smaller grains may be other relics of the overlying layer.
-2- The embedded grains may be sparse brecciated clusts in a sedimentary siltstone.
-3- We are near hematite ridge. Depending of the composition of the embedded material, we might see first embedded iron ore fragments.
-4- Embedded tektites of a meteorite; recently we have seen likely iron meteorites.

Well, the detail that interests me is the knobby texture, e.g. in contrast to smooth "blueberries"
I'd call these mulberries.
They appear to have internal structure, you can see where a 'pip' has weathered out and left a spherical gap.

This makes it look like these are clumps of course grained material cemented by a fine matrix.

[jccwrt]

Well, the detail that interests me is the knobby texture, e.g. in contrast to smooth "blueberries"
I'd call these mulberries.
They appear to have internal structure, you can see where a 'pip' has weathered out and left a spherical gap.

This makes it look like these are clumps of course grained material cemented by a fine matrix.

You can't really say much about their internal structure since we don't have any that have cracked open. The knobby texture could just be a consequence of uneven precipitation. They don't look all that different from iron oxide concretions to me.

[serpens]

Looks like there's a multi-stage history in that rock. I notice that many of the white veins (probably gypsum) don't have the alteration haloes around them. So it looks to me like there was initial fracturing associated with the movement of a reducing agent that bleached the iron, followed by fracturing not associated with a fluid. Not sure how the v-shaped vein fits into that history, though.

I believe you're correct in that there has been multiple instances of alteration/deposition through fractures. The thing is that if we accept that the sediment in Gale is horizontally bounded then if the initial fracturing was hydraulic, with high overburden pressure, hydraulic fracturing would be preferentially horizontal. As overburden was eroded and removed, pressure release would be vertical. It could be anticipated that there would be reactivation and extension of fractures over time which would account for those thin offshoots that seem to have Calcium sulphate deposits but no dark halo. It also accounts for the horizontal deposits without necessitating an evaporate, playa scenario.

[PaulH51]

REMS UV Detector Housing in this 1614 MAHLI and a montage with a little history.
We can see the recent cleaning of the finer dust from around the magnets and the darker sands on the deck, I've annotated the sol # and a brief description under each image. Once again reduced to meet the max upload limits.

Probably make a good GIF one day, but the file size may be a little on the large size and the alignment is not very consistent.

[jvandriel]

The Navcam L Panoramic view on Sol 1616.

Jan van Driel

[PaulH51]

Preview of the a de-bayered 1609 R-MastCam mosaic of Ireson Hill, using 30 of the 32 frames. I plan to assemble the full mosaic when the remaining frames are downlinked.
De-bayered in ImageJ, stitched in MS ICE. The greenish cast from de-bayering these files, has not been adjusted in this preview version

[Phil Stooke]

A very small move on sol 1616, less than a wheel diameter from comparison of Hazcams. The drive was supposed to be bigger, so presumably halted by tilt or other sensors. I will not update the map for it, but here is Jan's recent panorama in circular form.

Phil



PS "Here is the sol 1614 3x3 R-MastCam mosaic of the layered block "Aroostook River" mentioned in the 1614-1616 USGS mission update. "

I always wondered what happened to cousin Aroo.

[Phil Stooke]

Reprojected Hazcams from sol 1617 show we are now on the sand, a short distance south of the previous position. Map update this evening my time.

Phil



(approximate orientation only)

[serpens]

Phil Stooke's map stop 2 (current position) is at the channel through the dunes, so the reason for the seven sol diversion to the dunes (stop 1) with a short 2 sol layover remains something of a mystery. There must be something that caught the teams interest.

[Sean]

Sol 1617 Navcam right pano with extended sky

[HSchirmer]

Phil Stooke's map stop 2 (current position) is at the channel through the dunes, so the reason for the seven sol diversion to the dunes (stop 1) with a short 2 sol layover remains something of a mystery. There must be something that caught the teams interest.

Eh, looks like the rover ran over and cracked open a fair sized rock,
bottom right of the navcam image.

Might be worth checking out fresh fracture faces to see how they compare to the weathered exterior...

[fredk]

the reason for the seven sol diversion to the dunes (stop 1) with a short 2 sol layover remains something of a mystery.

In the latest update they say they wanted to compare the leading and trailing edges of the dunes. (Or do they mean they'll do both near here, rather than comparing stops 1 and 2?)

[serpens]

From the update " This site was selected to enable comparison of the leading and trailing edges of the dunes." implies this is a specific task for this stop. Could there be a delay on the requirement to have an extended stop for attempts at fault rectification on the drill?
I still have difficulty thinking of this area as dunes rather than ripples.