South from the landing site, sols 72-237, Starting the science traverse |
South from the landing site, sols 72-237, Starting the science traverse |
Sep 18 2021, 09:17 PM
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#601
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Senior Member Group: Members Posts: 2998 Joined: 30-October 04 Member No.: 105 |
The study of induration and lithification of sediments on Mars seems to me to be in a state of flux. We have many on-the-ground observations, currently from Curiosity as she scales Mt Sharp in Gale crater. And if course the current work of Perseverance in Jezero.
My general take is that without deep burial, compaction is going to be mild, and induration will be limited to low-temperature hydrothermal processes involving sulfates. This should prove to be an interesting trek. --Bill -------------------- |
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Sep 18 2021, 09:53 PM
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#602
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Member Group: Members Posts: 684 Joined: 24-July 15 Member No.: 7619 |
Although my 'inner voice' says a basalt, I keep finding ways to stray. The initial Abrasion on Sol 206 (shown above) is clearly sedimentary, poorly sorted, angular and poured in. The start of the abrasion was on that top 'weathering crust. The mineralogy of this section will be interesting. --Bill Actually, this kinda-sorta reminds me of the layering you see in 'pegmatite' in the Atlantic rift basin. Basically, in the same way that a drying sea, deposits different layers of less and less soluble salts, but because as magma cools, you get a similar effect because magma and that doesn't flash freeze into glass, has time to let mineral crystals "snow out" as the flow cools. The very bottom of the magma chamber has crystals of the first minerals to freeze, while the top of the magma chamber concentrates those minerals and elements that are the last to freeze- which is why diabase or dolerite anticlines are associated with gold, copper, silver deposits Basically, "applejack" the same way that people have made hard cider, and then freeze out the water into slush, and keep the fractionated / enriched liquid as a liquor. |
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Sep 18 2021, 09:58 PM
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#603
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Member Group: Members Posts: 362 Joined: 13-April 06 From: Malta Member No.: 741 |
What looks like light green colour coatings?
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Sep 18 2021, 10:29 PM
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#604
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Merciless Robot Group: Admin Posts: 8783 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
ADMIN: 9 posts moved to new topic for discussion of image hosting/size/etc.
-------------------- A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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Sep 19 2021, 12:11 AM
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#605
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Senior Member Group: Members Posts: 1043 Joined: 17-February 09 Member No.: 4605 |
.......My interpretation right now is that these are subaqueous sediment gravity flow deposits of altered or lightly weathered volcaniclastic sediment, essentially delta front turbidites........ The reason I suggested floodplain was the resemblance of Ingenuity images to ridge / swale configurations. |
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Sep 19 2021, 09:12 AM
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#606
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Newbie Group: Members Posts: 12 Joined: 15-August 12 Member No.: 6562 |
This SuperCam shot (Sol 206) makes me feel quite confused about the origin of this rock. It seems like a layer that has been altered from botton to top (attending to the higher degree of cementation in the lower part and the more massive appearance of the top). Even there are some translucent grains.
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Sep 19 2021, 10:15 AM
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#607
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Member Group: Members Posts: 662 Joined: 9-May 21 From: Germany Member No.: 9017 |
Sol 205 SuperCam Remote Micro Imager with sol 205 Mastcam-Z context and sol 206 Navcam context.
Judging from the Navcam image, the SuperCam looked at a rock slab from the same layer that was abraded next day/sol. Two sol 205 Mastcam-Z images (the overexposed ones) taken at the same time allow the distance and size of the SuperCam image to be calculated. If there is no systematic error in my calculations, the imaged circle has a diameter of about 44 mm and is about 2.4 m away from the Mastcam-Z. The average diameter of the grains (crystals?) is about 1.4 mm, corresponding to very coarse sand. However, the grains are angular and not rounded, and I cannot see any cement, matrix, or pores between the grains. The brighter material on some upper grain boundaries is external dust. Although it most likely belongs to the same layer, the interior of the abraded rock on sol 206 looks quite different. |
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Sep 19 2021, 01:40 PM
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#608
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Member Group: Members Posts: 662 Joined: 9-May 21 From: Germany Member No.: 9017 |
This SuperCam shot (Sol 206) makes me feel quite confused about the origin of this rock. It seems like a layer that has been altered from botton to top (attending to the higher degree of cementation in the lower part and the more massive appearance of the top). Even there are some translucent grains.
An interesting rock, indeed. Here is my processing of the same SuperCam RMI raw image with slightly enhanced colors, sol 205 Mastcam-Z context and sol 206 Navcam context. As for the cement: maybe that's not cement, but the start of weathering at the grain boundaries and/or very fine dust? The translucent grains seem to have a more olive cast compared to the opaque grains. |
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Sep 20 2021, 01:20 AM
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#609
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Senior Member Group: Members Posts: 2998 Joined: 30-October 04 Member No.: 105 |
Looking at these Super Cam images, I keep returning to a fractionated basalt. On the wind-abraded fracture surface I see olivine as the green-tinted transparent clasts and pyroxenes as the blue-tinted clasts (or phenocrysts) near the top. This could be considered an ambiguous specimen in need of coring.
Here is a terrestrial example of a differentiated igneous rock: -------------------- |
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Sep 20 2021, 02:51 AM
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#610
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Senior Member Group: Members Posts: 1043 Joined: 17-February 09 Member No.: 4605 |
For my part these images reflect somewhat poorly sorted clastic rock encompassing the range of angular and spherical shapes. The potential cement does not match the colour of the dust coating the upper surface of the rock and protruding parts of the fractured surface. The Jezero catchment is mafic and olivine rich so olivine particles could be anticipated in immature sedimentary rock.
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Sep 20 2021, 08:15 AM
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#611
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Senior Member Group: Members Posts: 2998 Joined: 30-October 04 Member No.: 105 |
I'm a mess.
I vacillate between these two views. --Bill -------------------- |
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Guest_Actionman_* |
Sep 20 2021, 05:10 PM
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#612
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Guests |
The texture seems to be about that of 20-grit sandpaper.
The crystals are very interesting! They seem to be the softness of salt as they easily grind into a white powder. |
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Sep 20 2021, 07:07 PM
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#613
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Junior Member Group: Members Posts: 75 Joined: 8-July 15 Member No.: 7566 |
Haha I feel the same way. Just about every week I flip flop between 'basalt' or 'sandstone'. That supercam image though... to me that really looks like the angular grains of a well sorted sandstone, which has a basaltic mineralogy (unsurpising given this is Mars we're talking about), though I understand how others see crystals where I see grains. I know scientists will be very eager to get their hands on this core. The layering and rock textures here are fascinating - perhaps the most interesting site Perseverance has reached yet
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Sep 21 2021, 12:33 AM
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#614
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Solar System Cartographer Group: Members Posts: 10146 Joined: 5-April 05 From: Canada Member No.: 227 |
Don't forget the possibility that the rocks originated as ash deposits rather than lava flows. Ash onto land, ash onto water, lava flows, basaltic material redistributed by fluvial action - there are lots of options, all with potentially similar compositions.
Phil -------------------- ... because the Solar System ain't gonna map itself.
Also to be found posting similar content on https://mastodon.social/@PhilStooke NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain) |
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Sep 21 2021, 10:50 AM
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#615
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Senior Member Group: Members Posts: 2998 Joined: 30-October 04 Member No.: 105 |
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