Home, Sweet Home, Dream becomes Reality |
Home, Sweet Home, Dream becomes Reality |
Feb 5 2006, 06:46 PM
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#201
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Senior Member Group: Members Posts: 1229 Joined: 24-December 05 From: The blue one in between the yellow and red ones. Member No.: 618 |
Hope no one minds, but I felt we have to have a new topic, right from the start, as a compendium of all the Factual Observations on this incredible structure...this Mother Ship from another world...this...(who said Burgess Shale? I laughed at that at the time. ) Who will start us off with a detailed description of what we see before us TODAY February 5, 2006 - Super Sunday.
(I'll be running from game to Exploratorium all afternoon! -------------------- My Grandpa goes to Mars every day and all I get are these lousy T-shirts!
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Guest_Sunspot_* |
Feb 15 2006, 12:44 AM
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#202
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Guests |
Latest pics are in, what do you make of this from the MI:
http://qt.exploratorium.edu/mars/spirit/mi...A0P2956M2M1.JPG Could those be tiny concretions? Here's the rock they're looking at: http://qt.exploratorium.edu/mars/spirit/fo...A0P1148R0M1.JPG |
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Feb 15 2006, 01:28 AM
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#203
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Senior Member Group: Members Posts: 1636 Joined: 9-May 05 From: Lima, Peru Member No.: 385 |
Latest pics are in, what do you make of this from the MI: http://qt.exploratorium.edu/mars/spirit/mi...A0P2956M2M1.JPG Could those be tiny concretions? It looks that the grains from the rock were cemented by some sulfate process. I am not geologist but the concretions seems to be of sand grain.. Rodolfo |
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Feb 15 2006, 02:41 AM
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#204
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Senior Member Group: Members Posts: 1229 Joined: 24-December 05 From: The blue one in between the yellow and red ones. Member No.: 618 |
It looks that the grains from the rock were cemented by some sulfate process. I am not geologist but the concretions seems to be of sand grain.. Rodolfo Geehossephat! That's a nice wrinkle. Totally different from the smooth-lumpy stuff at the base of the section. This rock is a piece of laminated float that presumably fell from the upper zone. Sandy for sure. Can't wait to see the MIs of the brushed circle. This story is getting more complex and interesting. Does anyone know from the "little birds" whether the sulfate has been confirmed by spectrometry? -------------------- My Grandpa goes to Mars every day and all I get are these lousy T-shirts!
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Feb 15 2006, 04:34 AM
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#205
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Junior Member Group: Members Posts: 30 Joined: 15-November 05 Member No.: 553 |
[font=Arial][size=6]
Geehossephat! That's a nice wrinkle. Totally different from the smooth-lumpy stuff at the base of the section. This rock is a piece of laminated float that presumably fell from the upper zone. Sandy for sure. Can't wait to see the MIs of the brushed circle. This story is getting more complex and interesting. Does anyone know from the "little birds" whether the sulfate has been confirmed by spectrometry? I am a retred geologist who has been reading this forum for several months and have just joined. I am surprised at the image of the upper beds at HP. I thought they were tuffs that had been modified by wind (x-beds) and would contain angular rock fragments. The rounded sand size grains , cemented by a softer ( sulphate?) looking material appears to change my view. Could the round grains be olivine? |
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Feb 15 2006, 05:50 AM
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#206
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Senior Member Group: Members Posts: 1229 Joined: 24-December 05 From: The blue one in between the yellow and red ones. Member No.: 618 |
[size=6] I am a retred geologist who has been reading this forum for several months and have just joined. I am surprised at the image of the upper beds at HP. I thought they were tuffs that had been modified by wind (x-beds) and would contain angular rock fragments. The rounded sand size grains , cemented by a softer ( sulphate?) looking material appears to change my view. Could the round grains be olivine? From the mouths of [font=Times New Roman]our beloved PIs, neb, "olivine-rich basaltic sands" seem to be the story for this here basin. To the uninitiated (like me) this would seem to present one of them quandaries, since water is deemed necessary to mobilise the sulfates, but also is deemed auntie-thetical to the persistance of olivine. I'm guessin' that the occasional splash[color=#33CCFF] of water might spread sulfates, while leaving the olivine still intact (though maybe it would take the edges off, if you know what I mean. I would dearly like to confirm the sulfates analytically, though. Patience is a virtue, I guess, though not a whole lot of fun. B) Shoot, I didn't ask for these pretty-colored fonts, but long as I got 'em...[color=#009900] -------------------- My Grandpa goes to Mars every day and all I get are these lousy T-shirts!
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Feb 15 2006, 05:24 PM
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#207
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Member Group: Members Posts: 153 Joined: 8-February 04 From: Phoenix, AZ USA Member No.: 9 |
From the mouths of our beloved PIs, neb, "olivine-rich basaltic sands" seem to be the story for this here basin. To the uninitiated (like me) this would seem to present one of them quandaries, since water is deemed necessary to mobilise the sulfates, but also is deemed auntie-thetical to the persistance of olivine. I'm guessin' that the occasional splash[color=#33CCFF] of water might spread sulfates, while leaving the olivine still intact (though maybe it would take the edges off, if you know what I mean. I would dearly like to confirm the sulfates analytically, though. Patience is a virtue, I guess, though not a whole lot of fun. Shoot, I didn't ask for these pretty-colored fonts, but long as I got 'em...[color=#009900] The MI's of the "float" block from the upper unit sure make it look like a tightly cemented sandstone. The grains are darker than the cement, and fairly well rounded. The sorting (range of grain sizes) looks to be moderate to well sorted (anyone help me out here with a scale for the MI's to get an idea of grain sizes?). These features, plus the very nice low-angle inclined cross lamination already seen, seem to confirm an eolian interpretation. However, the MI's of lower interbedded units are much different. There are several different grain types, the sorting is much poorer, and some of the larger grains look angular. There is also some indication of some fining-upward grain size trends in these thinner beds, too. I'll stick with my sediment gravity flow interpretation of these beds, for now, but there is more to be done here, too. I guess that the composition of the cement is still the big unknown to us outside JPL looking in. Hopefully this will be forthcoming, but there are still a few things we can say about it: In both units imaged by the MI, the grains do not look like they were compacted much before cementation. There is something called "minus cement porosity" that is measure of how much space there was between grains before the sandstone got lithified. You can get a rough idea of this by looking at how many grain-to-grain contacts you can see. In both the upper and lower units, there seem to be more than a few "floating" grains completely surrounded by the cement, suggesting that there was a lot of pore space between grains when the cement was precipitated. This makes me lean towards an aqueous-mediated cementation event under shallow subsurface conditions (i.e. groundwater) rather than burial diagenesis, pressure solution, or welding of tuff particles in a pyroclastic flow. -------------------- Tim Demko
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