[X] My Assistant

[atomoid]

Is that a glint of sunlight on one of the nodules near the top center (of Stu's pan), or just an artifact?
What a place!

what a place indeed... Oppy steals the show!!

i think your referring to the right side of the top left quadrant of Stu's wonderful MI mosaic
i see those from time to time, i think its just too bright for the sensor at the exposure level so it bleeds out a bit, perhaps..
im curious about the bloob just to the left of that bright glinting one, it has lines running diagonal to lower right. its kinda really strange, i dont see anythingn quite like it, i dont quite know what to make of it...

the cache of blueberries is so startlingly concentrated here, and since im not a geologist and have no reputation to lose I will go far out on my own breaking limb to suggest they didnt form in situ but were collected by erosional processes rolling into collecting cracks with a subsequent Endeavor impact resultant water percolation cooking them up with rinds and modified materials into something like a blueberry mud muffin cake layer filling, whatever it was it sure looks delicious!!
..but i sure do like the sound of the phrase ".. impact melt breccia with concretion clasts.." (thanks 'other Doug')

[Bill Harris]

These somewhat resemble devitrification spherulites (a type of spherule) that form during the localized crystallization of water-bearing glass...

I've been looking at these spherules and wondreing about the "rind" we see on many of them. You're probably close. Get a larger sample of examples with more images, get some idea of the color, maybe hit a flat surface with the snaggle-toothed RAT to get a fresh x-sectional view. And so forth.

I think these MIs are a view of the light-toned flat rocks, we haven't even gotten to the dark, coarse-textured ones yet!

--Bill


CR: you may be right. On second glance, it's not looking like the light-toned flat rock.

[CosmicRocker]

I'm hoping someone can post a context image showing us where these MI's were taken. It seems that the MIs display a denser concentration of spherules than many of the rocks we see in the pancams.

[CosmicRocker]

What? Another type of spherule in Meridiani? This is just too much. ...

There are an endless variety of spherules. Geologists love spherules.

[serpens]

These have a passing resemblance to the Gunflint Lake lapilli deposit originating from the Sudbury impact. (image source Minnesota Geological Survey). If these are lapilli would that not imply that the deposit was laid down at a distance from the impact site which would be a strong indicator that these were part of the pre-Endeavour impact terrain?

http://i1191.photobucket.com/albums/z468/s...pactlapilli.jpg

[elakdawalla]

I was thinking the same thing. As far as I understand it, a crater rim consists of preexisting target rock layers, usually overturned by the impact excavation process. I would think that most glass would be deposited with the impact ejecta, not in the crater rim. So if these are impact spherules, I don't think they could be from the Endeavour-forming impact, unless Endeavour's current "rim" is not actually the original rim but instead an erosional remnant of the ejecta deposited outside the rim, which turned out to be more resistant to erosion than the actual rim.

But this is all pretty arm-wavey geology. I need to go talk to an impact person, ideally someone who's familiar with the rover mission. I don't actually know anyone who answers that description. Hmm.

[Gladstoner]

.

[belleraphon1]

Know not suppossed to clutter but gotta say WOW OPPY.

Not even going to pretend to be a geologist.

This just proves the benefit of having long lasting rovers..... I remind my non-space following friends that Mars is a world and seeing ONE landing site area does not define the planet.

Keep going OPPY team!!!!

Craig

[Julius]

Could anyone recall the composition of Wopmay back in Endurance crater and the chocolate hills at Conception crater!?? I see a resemblance in these rocks here !!

[Bill Harris]

Blueberries concentrated in a linear outcrop (so it appears) made me think of a clastic dike.

Indeed, this fits very well with the observed textures of the bedding, etc, at this outcrop.

A quick reference to clastic dikes:

http://en.wikipedia.org/wiki/Clastic_dike

They can be relatively benign, like from fluidized injection from the weight of overlying strata, or by the sweeping of sediment into open fractures (like dessication cracks or the Anatolia lineations) or catastrophically, related to impact processes:

http://en.wikipedia.org/wiki/Upheaval_Dome

Your image is labeled "bonner clastic dike"-- what location/formatin is that? "Bonner" makes me think "Idaho".

From yesterday's color Pancams, the Blue of these spherules suggests to me more of an impact melt instead of an hematite concretion. FWIW.

--Bill

[Bill Harris]

the composition of Wopmay back in Endurance crater and the chocolate hills at Conception crater!??

Wopmay was, IIRC, Burns Formation with Blueberry concretions. Chocolate Hills was apparently a fracture fill.

--Bill

[centsworth_II]

Could anyone recall the composition of Wopmay back in Endurance crater and the chocolate hills at Conception crater!?? I see a resemblance in these rocks here !!

Wopmay and Chocolate Hills are altered pieces of Meridiani sulfate layers. These layers were laid down over millions of years on top of the older surface that Endeavour crater was formed on. Hopefully the rocks that Opportunity is looking at now are part of that older surface. If so, although they may resemble Wopmay and Chocolate Hills, they would have a totally different composition and history.

[Don1]

If this rock is Noachian aged, maybe it dates from the period of the Late Heavy Bombardment. Impact lapilli might be common in rocks from that period.

That said, I thought that impact lapilli were supposed to come in discrete layers. These look to be scattered evenly though the rock.

Nobody has said anything about the matrix. I think there is an excellent chance that the matrix is the source of the clays, but last night I compared the route map with the map of the clays from CRISM and noticed that the rover is a little north of the area where clays have been detected.

[ngunn]

(1) I thought that impact lapilli were supposed to come in discrete layers.

(2) I think there is an excellent chance that the matrix is the source of the clays, but last night I compared the route map with the map of the clays from CRISM and noticed that the rover is a little north of the area where clays have been detected.

1/ The upstanding 'fin-like' outcrop could in its entirity be considered a discrete layer. I'm not yet sure whether we are looking at a coherent stack of everted rim bedrock or a rubble-pile of ejecta in which the 'fin' is just one largish fragment that happens to be partly on edge at a plausible angle. Either way I'm with the pre-Endeavour impact lapilli idea for now.

2/ This is quite a small outcrop and any patch of clay minerals deriving from it may be too small for CRISM to resolve. There could still be clays to be found here, though undoubtedly there's a bigger patch up ahead. Will that prove to be associated with more exposures of lapilli-packed rocks? With luck we'll soon find out.

[centsworth_II]

...I thought that impact lapilli were supposed to come in discrete layers....

If they are lapilli, they may have been mixed with other material by impact or some other process, the mixture later becoming lithified.