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Rick Brinkman wrote:I don't see what the problem is guys. Seems logical to me.
Earthquake happens causing a new crack in the ceiling. Water starts flowing down the new crack forming a line of stalagmites on the floor. You date the stalagmites - telling you approximately when the ceiling crack formed.
If a bunch of ceiling cracks happened at the same time, especially in multiple caves, you probably have an earthquake event.
Personally, I think it's a pretty cool idea.
John Lovaas wrote:It looks like they are correlating the young formations with weather records, and the older formations using U-T dating.
John Lovaas wrote:I can appreciate the correlation between the speleothem dates and the other seismic dating methods- but without the other dates(sand blows, etc.), I think it would be tricky to point at a speleothem's age and go, "there was a seismic event at date X".
John Lovaas wrote:I suppose most all limestone caves have some kind of tectonic origin
ggpab wrote:Bruce Railsback provides a great atlas on speleothem imagery at http://www.gly.uga.edu/speleoatlas/SAindex1.html Some of the images do a great job at showing just how subtle the laminations are - http://www.gly.uga.edu/speleoatlas/SAimage0227.html
John Lovaas wrote:It looks like they are correlating the young formations with weather records, and the older formations using U-T dating.
Besides, counting to 200 is not that big a deal.
John Lovaas wrote:I can appreciate the correlation between the speleothem dates and the other seismic dating methods- but without the other dates(sand blows, etc.), I think it would be tricky to point at a speleothem's age and go, "there was a seismic event at date X".
Actually it is the reverse. The U/Th dates from the speleothems are most likely WAY more accurate and precise than any date generated for the sand blows, etc. The U/Th dates are the gold standard.
John Lovaas wrote:I suppose most all limestone caves have some kind of tectonic origin
You get nice fracturing from all sorts of non-tectonic processes, such as isostatic rebound and flexing of whole regions when glaciers melt which is happening throughout the great lakes basin right now, you get shrinkage when carbonate become more dense as they mature (think of mud cracks here), you can get pressure cracking when additional sediments are loaded on top of one part of a region and not another (think of the sediments of the Mississippi river delta causing regional stress patterns), etc etc. So yes, there is of course some reason why the fracturing happens, but no it does not need to be related to plate tectonics.
John Lovaas wrote:When folks are counting laminations, how do they determine what time period each lamination represents? If each lamination represents 1 "deposition period", how is the length of that period defined? If I'm off topic here, I apologize- I guess I'm still looking for an "Idiot's Guide to Paleochronology".
John Lovaas wrote:In a guitar class I took this summer, the instructor had us count to 5 while maintaining a beat. It was really hard ;-) 200 would be impossible for me! ;-)
John Lovaas wrote:I was just curious if it would be sufficient to have A) faults in the neighborhood of a cave, and B) dates from formations in the cave, and from A and B determine when there was seismic activity associated with the faults. Wouldn't it be good to have dates from "C"?
John Lovaas wrote:In my head, I had isostatic rebound as a kind of tectonic activity, so I'm not using the term correctly. I don't know squat about geology- I never even managed to take a class in college.
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