"Could the Meridiani Spherules be Surficial?" |
"Could the Meridiani Spherules be Surficial?" |
Jul 10 2007, 04:37 PM
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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 10 2007, 11:21 PM
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Junior Member Group: Members Posts: 42 Joined: 2-July 07 Member No.: 2646 |
MarsIsImportant, If the spherules are superficial, that is, not really a part of the Meridiani layered deposits then neither theory needs to explain their distributions or their relationships with the bedding.
Doug, You never give an inch, do you, even for the sake of friendly debate? I do not need to prove that accretion is taking place at Meridiani, but only to raise doubts that it might be. I think it is reasonable to think that rock coatings might have formed at Meridiani based, yes, in part on the appearance of pre and post brushed surfaces. The little bits of bright material left behind at the base of those spherules encourage me because if they were unconsolidated dust they might have been removed by violent air currents close to the spinning brush. Here is the abstract for a talk in which several MER scientists discussed fracture fills and rock coatings at Meridiani, not as processes from an ancient warm-wet Mars but as something that could have happened under conditions more like those found today. http://www.aas.org/publications/baas/v37n3/dps2005/424.htm Did you get a chance to read that Kraft and Greely paper? They seem quite willing to accept that rock coatings formed at the Pathfinder site. The rinds like Lemon Rind were thought by the MER team to be added to the top of the Meridiani strata after all other deposition was complete. They haven't said that the rinds are recent, but I maintain that they might be. The rinds sometimes wrap the corners of eroded blocks and occur in the ejecta of not-so-ancient Beagle Crater. My point is that erosion may not be the only process recently affecting the "rock" at Meridiani, which we should remember is barely rock at all. Spherules are embedded in "rock" allright but that is not proof that they formed or were deposited deep within the layered strata. This gets me to the MI evidence of the relationship between the spherules and the layers but I'll leave that for the next post. |
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