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#11
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Spheres coming from bedrock?
"OndaWeb" wrote in message ...
I wrote JPl some of this yesterday. Base on what Dr. Squires has said, it seems clear the spherules are being exhumed out of the matrix of the bed rock. But notice they are relatively scarce in the bed rock. But on the surface, epically outside of the crater, they are plentiful, virtually covering the entire surface. Thus it seems that the bedrock, thought to underlie the entire plain in Meridiani, must be filled with these spherules that are eventually "released" as the bedrock is eroded by wind. Perhaps the bedrock becomes the dust and sand of Mars. The spherules are left behind, at least in this area, to blanket the floor (or they may be blown and rolled from somewher uphill). And it seems likely the spherules are the source of the hematite. According to the "mineral map", wherever the spherules are, the hematite signature is strong (at the rim of the crater, outside the crater, some places inside.) Conversely the signature is weak where there are few spherules (in the bedrock, where the spectra of the soil was taken, and most significantly, where the airbags of the Lander squashed them into the soil). It seems to me the easiest explanation is fine volcanic ash (maybe cemented with some water from snows when the orbital eccentricity changes)is the bed rock and the spherules are hematite rich condensed globules. So any geologist know of a plausable process by which a volanic eruption would make both ash and hematite rich spherules? The rocks look for all the world like Archaean rhyolitic ignimbrites (colour, platy parting and all). Spherules are characteristic; coalesced pairs common. http://users.indigo.net.au/don/pr/dogsballs.html (sometimes in threes) (The haematite would be unusual though. ) The spherules are a puzzle (to me). The spherule texture is little different from that of the matrix. df. Roy Clymer " George" wrote in message . .. "scrodchunk" wrote in message om... The spheroid particles in the bedrock look a lot like those in the surface 'gravel' To me this suggests two likely things. a) the spheroids in the rock were formed in the same manner as those in the gravel and more interestingly b) a period of change occured where the planet changed from a state much like the current state (with spheroids in the gravel) into a state where sedimentary rock could form (such as a prolonged period of moisture, which has then returned to the current state. That's pretty interesting, because if there were prolonged wet periods on mars (ie before the atmosphere precipitated into icecaps) there was probably time for such that sedimentary concretions could form, rudimentary life could perhaps form too. It would be interesting to give the rock a good whack though, and see how solid it is. Ross. Unfortunately, the rovers left their rock hammers at home! And they call these contraptions "geologists"? :-) I would add that the spherules in the soil apparently originated from the bedrock, as it too contains the same spherules. "Joe Knapp" wrote in message y.com... "Timothy Demko" wrote Close-ups like this: http://marsrovers.jpl.nasa.gov/galle...2P2933M2M1.JPG continue remind me of textures and fabrics I've seen in travertine and sinter deposits. Would sinter deposits be associated with hot springs such as in theis New Zealand shot? |
#12
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Spheres coming from bedrock?
"Timothy Demko" wrote The interpretation of the bedrock as a volcanic ash, even an altered ash, has not yet been supported. In fact, the presence of cross beds: http://www.jpl.nasa.gov/mer2004/rove...s/image-1.html suggests that even if it is an ash, it's been transported by some sort of traction currents and is not a simple air fall. Cross beds I take it simply means that the layers are not always parallel--they diverge and converge sometimes? If so, how about this photo of the effect of "volcanic bombs": http://www.geo.hunter.cuny.edu/~cwang/impacts.jpg Wouldn't the layers in that photo be a simple air fall? It's interesting that last week Squyres said there were three main theories for the origin of the spherules: lapilli, solidified volcanic material, or concretions. He said the lapilli idea was "fading fast" on the logic that they look to be of a different material than the matrix. There has not been a word in the press conferences since about any progress along those lines. However, an interview with Ronald Greeley, Ph.D., Regents Prof. of Geology, Arizona State University Dept. of Geological Sciences, and one of the 7 Chairs of the Science Operations Working Group (SOWG) for Spirit and Opportunity, Tempe, Arizona this Wednesday was a bit surprising. When asked about the spherules, Prof. Greeley said: "The general consensus seems to be centering around two possibilities: "First, that they are what are called 'accretionary lapillae' * that is a volcanic feature that forms in certain kinds of eruptions in which material is added to a small nucleus like a little dust grain and these form these spherule masses." "Secondly, they could be some kind of precipitate * perhaps from water. In additional findings, there are some minerals that have been identified in the infrared that would suggest the presence of water since they form in water. In particular, if this is a volcanic terrain that we are looking at, the presence of these minerals might suggest this was a hydrothermal area." What--lapilli are fading back in and the other two theories (magma & concretions) are gone, to be replaced with "some kind of precipitate"? Continuing: IS THERE ANYTHING FROM ANY OF THE SPECTROMETERS OR ALPHA X-RAY THAT INDICATE WHAT THE SPHERULES ARE MADE OUT OF? "We can't measure the spherules individually * they are too small. We have to get the chemical and mineralogical signatures for the whole mass and then try to deduce what would be the composition of the spherules." SO TODAY AS WE SPEAK ON FEBRUARY 11, IS IT STILL UNKNOWN WHAT THE SPHERULES ARE MADE OUT OF? "Yes * that's a work in progress." .... AND ALL THIS IS ADDING UP TO A QUESTION ABOUT WHETHER THE PLACE WHERE OPPORTUNITY CAME DOWN ORIGINALLY MIGHT HAVE BEEN HOT MAGMA COMING UP TO THE SURFACE IN SOME KIND OF VOLCANIC ACTIVITY? OR AT LEAST HOT SPRINGS? "Yes. The evidence is sort of pointing towards the presence of a hot environment * hot for some reason and that's under debate right now. Volcanic activity, magma close to the surface, is one possibility." .... THE BIGGEST SURPRISE RIGHT NOW HAS BEEN THE HIGH AMOUNT OF SULFUR IN THE BEDROCK? "That was a surprise, yes. The measurements that have been made there suggest there is a very high percentage of sulfur present in the material and that there are these spherules that have been seen and reported earlier, those are still very curious features." "Such a high percentage of sulfur (in the bedrock) is unusual and this is what leads some folks to consider the volcanic origin (at the Martian bedrock), or at least volcanic processes to be involved. There are some minerals that have been identified in the infrared that would suggest the presence of water since they form in water. In particular, if this is a volcanic terrain that we are looking at, the presence of these minerals might suggest this was a hydrothermal area and sulfur is a component of such environments." SO THE BEDROCK MIGHT BE, IF WE WERE COMPARING IT TO THE EARTH, MIGHT HAVE HAD AN ORIGIN SIMILAR TO SAY YELLOWSTONE NATIONAL PARK? "Yes, to some parts of Yellowstone, that's right." http://www.earthfiles.com/news/news....tegory=Science Joe |
#13
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Spheres coming from bedrock?
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#14
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Spheres coming from bedrock?
"don findlay" wrote in message om... "OndaWeb" wrote in message ... I wrote JPl some of this yesterday. Base on what Dr. Squires has said, it seems clear the spherules are being exhumed out of the matrix of the bed rock. But notice they are relatively scarce in the bed rock. But on the surface, epically outside of the crater, they are plentiful, virtually covering the entire surface. Thus it seems that the bedrock, thought to underlie the entire plain in Meridiani, must be filled with these spherules that are eventually "released" as the bedrock is eroded by wind. Perhaps the bedrock becomes the dust and sand of Mars. The spherules are left behind, at least in this area, to blanket the floor (or they may be blown and rolled from somewher uphill). And it seems likely the spherules are the source of the hematite. According to the "mineral map", wherever the spherules are, the hematite signature is strong (at the rim of the crater, outside the crater, some places inside.) Conversely the signature is weak where there are few spherules (in the bedrock, where the spectra of the soil was taken, and most significantly, where the airbags of the Lander squashed them into the soil). It seems to me the easiest explanation is fine volcanic ash (maybe cemented with some water from snows when the orbital eccentricity changes)is the bed rock and the spherules are hematite rich condensed globules. So any geologist know of a plausable process by which a volanic eruption would make both ash and hematite rich spherules? The rocks look for all the world like Archaean rhyolitic ignimbrites (colour, platy parting and all). Spherules are characteristic; coalesced pairs common. http://users.indigo.net.au/don/pr/dogsballs.html (sometimes in threes) (The haematite would be unusual though. ) The spherules are a puzzle (to me). The spherule texture is little different from that of the matrix. df. Can you post a link to some pictures or description of archaean rhyolitic ignimbrites that look like what we are seeing on Mars? I don't doubt you Don, but that kind of thing just isn't found in my neck of the woods, so I'd like to see an example. TIA. |
#15
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Spheres coming from bedrock?
don findlay wrote:
It seems to me the easiest explanation is fine volcanic ash (maybe cemented with some water from snows when the orbital eccentricity changes)is the bed rock and the spherules are hematite rich condensed globules. So any geologist know of a plausable process by which a volanic eruption would make both ash and hematite rich spherules? If it is explosive, and high in Fe, the iron spherules could be formed easily by spatter and air resistance. Ever notice what shape welding rod spatter takes? Little balls. The rocks look for all the world like Archaean rhyolitic ignimbrites (colour, platy parting and all). Spherules are characteristic; coalesced pairs common. http://users.indigo.net.au/don/pr/dogsballs.html (sometimes in threes) (The haematite would be unusual though. ) The spherules are a puzzle (to me). The spherule texture is little different from that of the matrix. df. Not necessarily strange. 1.4Ga rhyolite ignimbrites and tuffs around here here (Earth) are fairly high in Fe and Mg, AND amazingly enough some of the crumbly stuff contains iron amygdules. I think I have piece in the basement somewhere. Iron is a mix of magnetite and hematite. Some seems to be primary, and some secondary deposits. Saw a paper at GSA North Central last spring where people were debating biogenic or abiogenic origins of iron spheres in this ore and possible bacterial involvement in forming the spheres. Much of the SE Mo iron industry was founded on rhyolitic Fe rich deposits. Even the granite around here is magnetic. On the other hand, maybe I have been teleported to Mars, and no one told me. |
#16
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Spheres coming from bedrock?
How about this. At one time the planet had rings. Rocks in the rings gently
collided with one another until they all reached a uniform size and spherical shape. The rings' orbit gradually declined until the dust dispersed over the whole planet and the heavier spherules fell along the equator, here into a soft volcanic dust pillow. Either that or Martians are deer. |
#17
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Spheres coming from bedrock?
"don findlay" wrote in message om... (don findlay) wrote in message . com... "OndaWeb" wrote in message ... I wrote JPl some of this yesterday. Base on what Dr. Squires has said, it seems clear the spherules are being exhumed out of the matrix of the bed rock. But notice they are relatively scarce in the bed rock. But on the surface, epically outside of the crater, they are plentiful, virtually covering the entire surface. Thus it seems that the bedrock, thought to underlie the entire plain in Meridiani, must be filled with these spherules that are eventually "released" as the bedrock is eroded by wind. Perhaps the bedrock becomes the dust and sand of Mars. The spherules are left behind, at least in this area, to blanket the floor (or they may be blown and rolled from somewher uphill). And it seems likely the spherules are the source of the hematite. According to the "mineral map", wherever the spherules are, the hematite signature is strong (at the rim of the crater, outside the crater, some places inside.) Conversely the signature is weak where there are few spherules (in the bedrock, where the spectra of the soil was taken, and most significantly, where the airbags of the Lander squashed them into the soil). It seems to me the easiest explanation is fine volcanic ash (maybe cemented with some water from snows when the orbital eccentricity changes)is the bed rock and the spherules are hematite rich condensed globules. So any geologist know of a plausable process by which a volanic eruption would make both ash and hematite rich spherules? The rocks look for all the world like Archaean rhyolitic ignimbrites (colour, platy parting and all). Spherules are characteristic; coalesced pairs common. http://users.indigo.net.au/don/pr/dogsballs.html (sometimes in threes) (The haematite would be unusual though. ) The spherules are a puzzle (to me). The spherule texture is little different from that of the matrix. df. ______________________________ (PS. The spheres, maybe pyrite (altered to haematite)) Based on what? They have yet to release any results on the TES analysis of the spheres. If they are hematite, they are the lightest-colored specimens of hematite I've ever seen. Oh well, I suppose we will have to wait and see what NASA finds. |
#18
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Spheres coming from bedrock?
"John" wrote in message ... How about this. At one time the planet had rings. Rocks in the rings gently collided with one another until they all reached a uniform size and spherical shape. The rings' orbit gradually declined until the dust dispersed over the whole planet and the heavier spherules fell along the equator, here into a soft volcanic dust pillow. Surely you jest. Either that or Martians are deer. Surely you jest. |
#19
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Spheres coming from bedrock?
John wrote:
Either that or Martians are deer. hey - the little critter with the rabbity ears! he leaves his martain raisins in the sun. - nate |
#20
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Spheres coming from bedrock?
" George" wrote in message ...
"don findlay" wrote in message om... "OndaWeb" wrote in message ... I wrote JPl some of this yesterday. Base on what Dr. Squires has said, it seems clear the spherules are being exhumed out of the matrix of the bed rock. But notice they are relatively scarce in the bed rock. But on the surface, epically outside of the crater, they are plentiful, virtually covering the entire surface. Thus it seems that the bedrock, thought to underlie the entire plain in Meridiani, must be filled with these spherules that are eventually "released" as the bedrock is eroded by wind. Perhaps the bedrock becomes the dust and sand of Mars. The spherules are left behind, at least in this area, to blanket the floor (or they may be blown and rolled from somewher uphill). And it seems likely the spherules are the source of the hematite. According to the "mineral map", wherever the spherules are, the hematite signature is strong (at the rim of the crater, outside the crater, some places inside.) Conversely the signature is weak where there are few spherules (in the bedrock, where the spectra of the soil was taken, and most significantly, where the airbags of the Lander squashed them into the soil). It seems to me the easiest explanation is fine volcanic ash (maybe cemented with some water from snows when the orbital eccentricity changes)is the bed rock and the spherules are hematite rich condensed globules. So any geologist know of a plausable process by which a volanic eruption would make both ash and hematite rich spherules? The rocks look for all the world like Archaean rhyolitic ignimbrites (colour, platy parting and all). Spherules are characteristic; coalesced pairs common. http://users.indigo.net.au/don/pr/dogsballs.html (sometimes in threes) (The haematite would be unusual though. ) The spherules are a puzzle (to me). The spherule texture is little different from that of the matrix. df. Can you post a link to some pictures or description of archaean rhyolitic ignimbrites that look like what we are seeing on Mars? I don't doubt you Don, but that kind of thing just isn't found in my neck of the woods, so I'd like to see an example. TIA. Link? No, unfortunately. They'd be just rhyolites to the survey. Otherwise known as "ringing rock", which rhyolites generally are. You can have great fun playing tunes on them, and cut slices ring like tubular bells (glass). Google up search terms "bipyramidal quartz" ignimbrite rhyolite flows flow spheres spherical etc. Given the quartz, the whorly ignimbritic texture, and the glass-like nature of the rock, the spheres seem to be some sort of growth in an incandescent state (maybe it rained or something, and caused nucleation (of what though?) , and the spheres got entrained in what might have been some sort of gas flow). Because they do occur in trains.. The spheres I'm thinking of (which are unusual in rhyolites generally, but common in these particular units) are lithic. But having seen the rhyolitic-looking rocks in the mars pics (long shot though and should be able to qualify), spheres of pyrite (which don't occur in them) did nevertheless come to mind. You see pyrite spheres in funny things, and the alteration to haematite figures I guess. |
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