"Could the Meridiani Spherules be Surficial?" |
"Could the Meridiani Spherules be Surficial?" |
Jul 10 2007, 04:37 PM
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#1
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Junior Member Group: Members Posts: 42 Joined: 2-July 07 Member No.: 2646 |
I have been reading the response to the reponse to impact-surge linked by Dr Burt in post 170. The MER team objects to the impact-spherule explanation because " The spherules are dispersed nearly uniformly across all strata." I agree that is a valid criticism. It is very much like Dr. Burt's criticism of the MER team's hypothesis, that spherule distributions are not consistent with any conceivable ground-water movement regime that should have controled the development of concretions. I agree strongly with this point of Dr. Burt's as well. Neither theory does a good job of explaining the distribution of the spherules. Also, neither theory does a good job of explaining why the spherules do not apparently disturb the bedding.
There may be a solution in a possibilty that I now raise with some trepidation. I think that there is a chance that the spherules are superficial, and not an integral part of the Meridiani strata at all. This probably sounds crazy to many readers, but before rejecting it outright remember that science is at kind of an impasse on this and could use a new idea. If the spherules are superficial this would explain a number of puzzling observations. The layering at Homeplate and Meridiani is most simply explained by impact-surge. It is elegantly and inescapably explained by impact-surge. The impact-surge authors have also tried to explain the Meridiani spherules as part an impact event. If doubts are raised that the spherules are integral to the deposit, this would not in any way be inconsistent with the impact-surge origin of the layered structure. On the contrary, an objection to impact surge would be removed. I intend to start another thread under Opportunity to discuss this question. The first posting should be mine and should be an organized outline of how it might be possible that the spherules have been mis-interpreted as part of the Meridiani layered deposit. I am working on it. If anyone wants to start in on me with the obvious objections, do it here for now. Maybe Dr. Burt would like to respond. No matter what the details of spherule formation in an impact or spherule deposition in the impact sediments, the very uniform distributions that we see are troublingly unlikely. Random distributions are possible from explosive dispersal but less likely than some kind of clustering because of the rapidly changing conditions in the surge cloud. The more-uniform-than-random distributions of spherules on rock characterised by MER-team analysis cannot be explained by impact surge. |
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Jul 24 2007, 02:39 PM
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Junior Member Group: Members Posts: 42 Joined: 2-July 07 Member No.: 2646 |
tglotch, Thanks for that information about the hematite at Gusev (your post 49). I guess that it doesn’t have any obvious implications for the origin of the spherules at Meridiani.
I am seeking a low-temperature formation mechanism that could operate under recent Mars conditions because for me an “exotic” process would be one that requires a warm Mars. It is still an extraordinary claim that Mars once had a climate that would allow liquid surface water or near-surface groundwater. The MERs have added no evidence of persistent surface water. They have discovered overwhelming evidence of water-catalysed chemistry, but no structural evidence of beaches, lake-bottoms, channels or water-tables that put the chemical activity in an Earth-like context. Those are very likely impact sediments at Meridiani. We have seen far too much evidence of water chemistry for it's origins to lie mostly in a brief warm period early in Mars history. In the Columbia Hills the evidence of aqueous chemistry is complex and mystifying, so much so, that it is now being explained as water interacting with volcanism, but again there are no clear signs of bulk liquid water. Volcanically heated waters must be fairly rare but I think that much of Mars surface will turn out to be as chemically complex as the Hills. Water chemistry has been happening there in slow Martian ways over the whole history of the planet. |
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Jul 24 2007, 04:21 PM
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#3
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Founder Group: Chairman Posts: 14434 Joined: 8-February 04 Member No.: 1 |
....in your opinion.
It's time to bring this thread to a close. |
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