This is going to be a very interesting stop on the traverse. I want to say "the most", but it keeps getting better. This is one reason why I've been jumping up&down waving my arms about doing a thorough leg of the traverse across CY, from the Meridiani side, across the rim remnant and into the Endeavour bowl. The depositional, weathering and erosional history of this area is so incredibly complex that we need to understand this history to understand the details.

Good points, dburt. I'm glad that you weighed in. The "hollow" appearance of the spherules doesn't bother me, but it provides another clue (or puzzle-piece). What it tells me is that the interior has a different "hardness" tenacity" "gooeyness" (whatever) than the outer rind. These spherules have been here a LONG time and have been through a lot of secondary, tertiary and quad-ternary mineralization. And that is beyond what a fresh spherule was like. We are seeing broken spherules that have been gently "sandblasted" by aeolian erosion for aeons. We need to see more MI examples, under several different lighting conditions. And the snaggle-toothed RAT needs to section a couple of fresh spherules.

I'm waiting for tdemko to weigh in. I see several "sedimentary" structures that are taunting me. Something has happened there.

And I see that "they" are calling it "outcrop" without choosing a name, yet. I'm still pushing for the Gracie Allen Formation...

--Bill



May well be. Just after Oppy hitthe high point of Shoemaker Ridge, she started heading downhill to the West side of CY, so we never got a good, close view of the current stop. But IMO, your image is close (and if not the same spot, it's the same outcrop line on the hillside).

I thought they were calling the whole area Fin Ridge or something like that... though I guess they need some kind of separate name for just the outcrop within the ridge.

BTW, Gracie Allen Formation? I *like* it!

-the other Doug

I'm on tenterhooks waiting for some imagery and APXS work that would indicate whether or not these spherules are deformed hematitic concretions or some form of lapilli. If lapilli, the big question would be whether they were formed by volcanic or impact processes. There is plenty of evidence on Mars for both processes.

Of course, this rock bed could have been formed by a combination of the two processes -- volcanic lapilli could have been spread around the fringes of the impact target sites for any one of the very large craters in the area, and been caught up in a moving tide of impact melt to become clasts in a melt matrix. The same thing could have happened with concretions being embedded in impact melt, and impact-generated lapilli could always have been caught up in a pyroclastic flow of some kind that left them embedded in tuff.

Isn't it fun how impacts are both a blessing and a curse? A single impact into an intact pile of rock beds shows you wonderful evidence of the emplacement and composition of the beds over time, and exhumes rocks from deep within the strata. On the other hand, throw impact after impact onto a set of rock beds (as happened during the LHB) and you get a ground-up, brecciated set of jumbled strata, greatly enriched by impact melt (which can have profoundly altered composition from the target rocks). And with each large impact you're creating new impact melt that is an amalgam of the elements not just in the surviving rock beds but also in the impact melt already emplaced by prior impacts, and in ejecta from other impacts that could have been transported there from hundreds of kilometers away (and exhumed from very different depths of strata). It seems to me it would be almost impossible to straighten the whole mess out into its original emplacement and compositional stratigraphy.

-the other Doug

They called it "half Fin" at one time last week, but several of the pancam sequences have been called simply "outcrop".

Just a thought. Eight years of trundling over the Burns Fm can do that to you...

--Bill

I've heard a lot of well thought out theories on these, but six bucks and my right ... spherule says these are the same hematite concretions we've seen across the rest of Meridiani.

EGD, I think you might lose that bet.

I am betting this is not hematite simply because these are hollow spherules; and all of the broken hematite spherules we have seen in the past have been solid.

I'm not convinced that the current outcrops were visible from the sol 2751 position.

Just to echo the sentiments of others, seeing these ancient rocks from the early days of the inner solar system's formation is incredibly fascinating. I've long wondered what the rocks from the bombardment phase looked like. Now, we may be getting to see them for the first time.

Welcome to the Hadean.

This rather nice photo shows "a close-up of a partially devitrified black obsidian from the island Lipari, Italy, with lots of small spherulites in it" that to me at least show similar internal structure to the objects found by Oppy. See the section on "Spherulites and Wall-lining Banding" on this page for details on the growth of spherulites.

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wow, some of those look very similar to the "spherules" in this Oppy image

http://qt.exploratorium.edu/mars/opportuni...M5P2935M2M3.JPG

I can barely comprehend the conditions in the vicinity of a large impact. Can you imagine what it was like here at the time of the Miyamoto impact? "Plinian" would seem mild in comparison.

--Bill

Well, since you asked...!

I'm going to have to go with ElkGroveDan's bet and say that I think that these spherules are the same type concretions that have been encountered in the younger, sulphate-bearing units at Meridiani. A while ago, I posted a summary of what the various stratigraphic and stratal geometric relationships between the units at Cape York that could be imaged by MRO, before Opportunity arrived there. As has been illustrated in the published papers, in general, the concretion-bearing sulphate strata onlap the impact-deformed older strata at the crater rim. The crater rim strata were a positive topographic feature throughout the initial time of deposition, and presumably, were eventually buried. This resulted in the apparent angular unconformity we see right now. The surface of the unconformity, however, seems to be quite complicated, which probably should be expected. Not only did it experience impacted related phenomena and ejecta deposition, but also weathering and colluvial deposition pre- and during the Meridiani "transgression" (or glacial advance, depending on your interpretation!). I think right now Opportunity is seeing some of the colluvial and initial Meridiani units in an angular, unconformable relationship with the tilted older strata. The same diagenetic phenomena that created the hematite spherules in the Meridiani strata would also have affected the immediately underlying deformed strata. Unconformities almost always are also boundaries important to subsurface fluid flow (aquacludes/barriers and aquitards/baffles), and can show distinct features reflecting perching/ponding of fluids and/or concentration gradients. The underlying deformed strata likely had zones or units of differing porosity and permeability, as well as original compositional and textural differences. The fluids that created the ubiquitous hematite spherules in the sulphate units must have also diagenetically altered the units at and below the unconformity.

Ah! That lit a light for me!

I was thinking that if the matrix was not the same sulfate sandstone that the hematite concretions formed in, that the sphereules could not be the same hematite concretions. But now I see that the same groundwater which formed the concretions in the Meridiani sulphate layers would have permeated and perhaps formed the same concretions in Endeavour's rim material. Thanks for the illumination.

Hi, Tim. So you think that the spherules are just the hematite concretions? Good possibilty. But we'll examine more examples and decide why they (apparently) have a different internal structure and why they (apparently) weather differenly. More color Pancams up today, she'd preparing to RAT/Brush and part of The Outcrop With No Name has been tagged "Kirkwood", P2560.

This is complicated. If we were there, we'd all be at the outcrop flat on our bellies with handlens, brush and hammer busy.

--Bill

We've seen blueberries split in half, and IIRC they looked something similar to what we're seeing now. Unfortunately I can't recall the sols... Did you have particular old blueberry MIs in mind, Bill?

Oh, my there are about a gazillon MIs to look through. Seems like they were earlyish MIs, like pre-Purgatory. They were "similar"-- rind and core, but maybe I think "different" because Hope Springs Eternal. These "seem" to have a more pronounced internal structure, but remember, the wind in this vicinity is strong and persistent enough to keep the pavement down on the bench swept clean and this outcrop uncovered, so the internal structure may be visible due to unusual aeolian erosion.

We'll be seeing a LOT more on the next few days.

--Bill

That was three days ago. So are we still missing the R5s? I thought we'd have this nailed by now.

R pancam aside, the L257 don't have the same response as the hematite concretions, so if they are concretions there are differences in makeup. The lack of blubes on the top of CY would seem to imply that it was not overrun by the Burnes materiel so if they are concretions (not necessarily hematite) then this implies significant groundwater at the inner rim of the crater with the consequent implication of a lot of water within the crater. (Also indicated by the response of the fill that over-ran the NW crater wall).

I think that identification of the matrix materiel will be a key factor in determining the provenance of these spherules but I think I will tend towards a cluster of impact related spherules/lapilli. While we have seen a few hollow, split blueberries on the plains these have been few and far between and we haven't seen anything like this outcrop before. The 'junk' that dburt drew attention to could possibly be clasts ripped up in a ground surge rather than concretion nucleation sites but as Bill Harris said, these examples have been subjected to long, slow erosion. Preferential erosion seems more likely in lapilli than concretions. Roll on the APXS

.

This part of the outcrop does look like a fin. Funny weathering anyway.
Click to view attachment
This anaglyph might be a bit difficult to view, because the "fin" is just on the edge of the pancam images.

That really is a great point. Looking at the rocks around Opportunity now, we have seen several apparently different rock types that all seem to have spherules in them. That would fit nicely with your hypothesis. I hope we have more than one MI target around here.

Yeah, so did I. For some reason all of the sol 3063 Milnet images are apparently stuck somewhere in the pipeline, and to make matters worse, all of the subsequent image sets do not include the R5 filter. Instead of running an "Rall" sequence (meaning R1-2-3-4-5-6-7), recent sets have been R1-2-4-6-7. I just noticed that we should get a full right filter set on sol 3067 (pancam_Kirkwood_PreRatBrush_L234567Rall). I think that will be an important set to keep an eye on.

In the mean time, I have spent the evening studying the calculated IR false color image algorithm that I have been using to identify hematite. After comparing the right filter band-passes to some hematite IR reflectance spectra, it appears that the R4 filter should work as well, if not better than the R5, so I think I can work with the recent image sets. I'm working on some outcrop images and will hopefully be able to post something tomorrow.

The Planetary Society monthly report is up:

September Report

Wow...

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And look at the bottom of this one... shiny veins..?

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I think Oppy is going to be considerably delayed hitting that 37k mark. Whether those turn out to be blueberries or not, these structures are very different from anything we've encountered before, and I'm sure the team will be spending a good stretch of time here applying the rovers' reduced toolset to try and figure out what this is and how it came to be.

A 3D look:
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Love those crazy web-like bright veins.

Here's an L7/R1 anaglyph:
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Please do! I worked with the "IR ratio image technique" for a while, but got sidetracked and still use my "TLAR" method.

--Bill

For comparison the first is a photo taken this afternoon of some hollow spherules, type devitrification lithophysae, from Cerro El Lobo, Tepetate, San Luis Potosi, Mexico, from a broken hand specimen I collected in 1985 (cf. my earlier posts 182 and 207). This is a topaz rhyolite (the light is glinting off a small topaz crystal in the large lithophysa to the left), much richer in water and fluorine than anything expected on Mars, and the groundmass has completely devitrified (following formation of the lithophysae). The typical onion skin texture is evident.
Click to view attachment
The second photo from this afternoon is shows more typical devitrification spherulites, from a weathered specimen collected last March by my colleague in the Superstition Mountains east of Phoenix, Arizona. The spherulites, especially broken ones in the lower center, clearly show the radiating microcrystalline texture that is typical. The groundmass is a somewhat perlitic (gray hydrated) obsidian, not devitrified. The spherulites, unlike the lithophysae, are resistant and weather or break out of the rock.
Click to view attachment
Hope these photos prove instructive; I was a little dissatisfied by what I found on the web (although Gladstoner's in 206 isn't bad). In both photos, note the extreme variation in size over a small area (also typical of concretions, but not Mars blueberries). In any case, the MI Mosaics of Stu in post 173 seem to show a rather large variation in size over a small area, also suggesting (together with the unusually close packing) that these might something other than the typical blueberries.

Sorry it has taken so long, but I generated 15 of these images covering much of the outcrop, and that took a long time. I was hoping I could stitch them all together, but that is not working, so I'll post it in pieces.

These are false color composites using right filter images and ratios of the images. Although some of you may not believe the uncalibrated, raw jpeg images can be used to do anything consistent, this algorithm has very consistently identified hematite on Meridiani Planum. I have looked at hundreds of these images and in all of them hematite appears as a bright, canary yellow color. I suppose that some other mineral that has a similar IR reflectance spectrum to hematite's might also appear yellow with this technique, but I don't think we have seen any such minerals on Meridiani.

As you can see, there appears to be a lot of hematite around here.
Click to view attachment
As I look at this I wonder if it may be similar to something we've seen once before. If you look closely at the left side of this pano and also the bottom right you can see ares where a bluish rock appears to be behind an encrusting layer of hematite. Do you remember seeing something similar on a target called Chocolate Hills?

Although I have yet to find the MI images I *think* I remember of fractured blueberries, this hematite concretion picture on the left from 2004 (!) is consistent with the harder rind/softer interior spherules we're seeing presently in the right frame.

Click to view attachment

Thanks, Tom. Now we "know" what color this puzzle piece is. Chocolate Hills, if I recall correctly, was decided to be a fracture fill.

--Bill

Yes, Chocolate Hills was a fracture fill, but it was a fill composed largely of closely packed, hematite concretions of various sizes, held together by an intergranular cement of hematite. All of these rocks do not look like Chocolate Hills, but some parts of them do.

That first pano I posted was just left of where the rover is doing IDD work. The following picture is just to the right.
Click to view attachment

I don't know about Opportunity previously seeing hollow hematite concretions, but here is a figure showing some solid-looking fragments along with experimentally grown "blueberries".

Edit: I just noticed that the Meridiani blueberries are measured in mm while the lab-grown berries are in um. So the lab berries are in reality about one thousandth the size of the real blueberries.

Click to view attachment
http://www.sciencedirect.com/science/artic...032063312000736

CR: very good. On your IR ratio images, do you know what shows as the cyan color? The magenta is shadowed areas.

Centsworth: Not a problem. Every Blueberry started out as a um-sized seed. It is telling that the lab-grown variety fracture te same way as the Meridiani BBs.

--Bill

I found a paper describing the methods that produced the synthetic sphereules in my last post. Also more comparisons with fractured Meridiani concretions.

"Comparison of morphology of whole and broken spherules.... Fracture surface textures in both sets of spherules are consistent with a spherulitic (radial) growth."
Click to view attachment
http://ia600607.us.archive.org/30/items/na...20080012477.pdf


In my ignorance, I find it hard to imagine the radial-structured spherules described above becoming hollow with an outer shell. But I found another paper, quoted below, which describes a possible rind formation process for hematite concretions. I don't know if it's an either/or situation or if both processes can be at work.

"....Field observations and numerical simulations indicate that spherical iron oxide concretions can form in a variety of host-rock conditions..... Laboratory tests indicate that chemical gradients between the inside and the outside of these spheres cause diffusion of Fe ions toward the outer perimeter of the amorphous sphere, forming a rind. The rind then grows inwards due to diffusion within the sphere, and may produce 'onion layering'. Continued diffusion, dehydration, or changing temperature are a few of the factors that may further affect the secondary internal structure-forming processes...."
http://archive.li.suu.edu/docs/ms130/AR/chan7.pdf

Bill: I can't make a general comment about the cyan colors, but after looking at about 1000 of these images in my collection from Meridiani Planum, my experience suggests that most of the time the Burns formation rocks appear green. However, sometimes they show up as cyan. I don't know what causes the difference, but it doesn't appear to be simply variability between the uncalibrated images, since sometimes the sulphate sandstones show up as green and cyan in the same image. It may be related to a dust covering, or something else.

See, for instance, the following IR ratio image from sol 423 showing the sandstone in shades of green and cyan, loose dust and sand in purples and greens, and acres of yellow, blueberry armored drifts.
Click to view attachment

edit: I just remembered that Homestake vein was also cyan.

On Sol 30 there was an MI image of a RAT hole with two blueberries that had been sliced open. They look a lot different from the present spherules. There is almost no internal structure visible, and no sign of a core or a crust.

Sol 30 sliced blueberry

Edit: Also on Sol 162, another sliced blueberry with only very faint internal structure.

Sol 162 blueberry

Thanks for that pic Don. I was thinking I had seen such an image and remembering no hint of internal structure.

I cannot stop roving through these images….

http://qt.exploratorium.edu/mars/opportuni...M5P2277R2M2.JPG

http://qt.exploratorium.edu/mars/opportuni...M5P2280R1M1.JPG

http://qt.exploratorium.edu/mars/opportuni...M5P2280R2M1.JPG

http://qt.exploratorium.edu/mars/opportuni...M5P2281L7M1.JPG

http://qt.exploratorium.edu/mars/opportuni...M5P2281L2M1.JPG


Show these images to some friends who get it. Others can only see a of bunch dirt and stone and say … ‘so what’.

For me…can close my eyes and feel the ages old breeze wafting past…. the burn from the cold light of Sol. Want to dip my hands in the ‘dirt’ and sniff the place….. Tell me your tale Mars.

Wow…. Love this place.

I absolutely know what you mean, my friend, and so, a gift for you, and everyone else who "gets it"...

Click to view attachment

As the great KSR put it so well...

On Mars... on Mars... on Mars...

Absolutely gorgeous!!!!!!

I stand transported....

Thank you Stu....

Craig

A bump on sol 3070 and some nice low-sun shots:
http://qt.exploratorium.edu/mars/opportuni...0M1.JPG?sol3070

With respect to the new berries, recall that Cape York does not have an orbital hematite signature. So if there are substantial numbers of berries there,...?

Precisely, CR. Or maybe, exactly? Over the years I've learnt that the various shades of blue, indigo and burple (bluish-purple), and the various salmons, ochres and tans and the shades of brown of the L257 images (and the other R721 palette) all appear to belong to consistent-appearing rock types. I've been able to identify basaltic, hematitic, "Type A" and "Type B" (ie, unknown, but the same type) rocks. And one of these days we'll get a handle on what this means, but fo rright now, consistent image processing to get consistent results is the key.

Got a new stack of Pancam images from a new outcrop and possibly some MIs. As the phrase goes, yummy.

--Bill

Nicely composed front haz-cam:

Click to view attachment

The rock looks almost chalky in nature, makes me want to pull out a pocket knife and see how it carves! But, considering its wind resistance, maybe it's pretty tough...?

Just one more for this evening:

Click to view attachment

Very weird rocks!

I stand transported too!
An amazing color & stereo tour of an amazing place, thanks everyone !

I have to admit to reservations over the identification of these spherules as hematite concretions. Compare this treatment of a known control from Victoria Crater with this new feature, using identical processing.
Click to view attachment
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Now compare with a chunk of suevite (Chester Lake I think).
Click to view attachment

I feel that the spherules and matrix in the ledge are primarily basaltic provenance but whether lapilli or devitrified glass is open.

I wasn't aware of that. Either the hematite we see in the rover images of this outcrop is limited in extent to the point that it is not visible to the orbiting spectrometers, or the raw jpeg analysis is faulty. I certainly have no legs to stand on if I try to defend an analysis based on uncalibrated imagery. All I can say is that that specific image algorithm has flawlessly identified hematite on the plains since Opportunity first landed. The geology of Cape York is quite different from the plains. There could very well be a mineral in these rocks that has a similar spectral response in the ratios of R1/R2 and R4/R7. I'm not enough of a spectroscoper to suggest which mineral/s that might be.

Devitrification reminds me of scumbling. There is a delightful novel written by William Wharton called The Scumbler.