Outdoor (out of cave) flowstone.

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Postby bcrowell » Apr 8, 2007 5:57 pm

Half a thread hijack, but I have a question(s) for Teresa, about the Mg concentration remaining constant.

Was the water saturated with respect to dolomite too, or just calcite?
and, although you can't easily test this and it's probably just a guess, was the constant Mg concentration a function of slower precipitation kinetics for dolomite when compared to calcite?
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Postby mgmills » Apr 8, 2007 6:25 pm

mabercrombie wrote:I think its called travertine when it is outside. I know where that stream is and its pretty amazing.


Marty - for another good example you and the Chattanooga guys need to check out the formations on the rock wall (by the last row of gas pumps) at the "Scot Market" in Kimball TN next time you are in the area.
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Postby barcelonacvr » Apr 8, 2007 7:08 pm

Evan wrote:Very interesting Teresa, thank you that did help! Marl is a new one to me. Very interesting! Thanks a google!




A lot of the lakes near me to the North are "mined" or should I say scooped for Marl....think slurry.Interesting stuff indeed.
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Postby mabercrombie » Apr 8, 2007 7:30 pm

I will take a look at the Scot market the next time im up there.
Im Marty Abercrombie
and I approve this message
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Postby Teresa » Apr 9, 2007 10:24 am

bcrowell wrote:Half a thread hijack, but I have a question(s) for Teresa, about the Mg concentration remaining constant.

Was the water saturated with respect to dolomite too, or just calcite?
and, although you can't easily test this and it's probably just a guess, was the constant Mg concentration a function of slower precipitation kinetics for dolomite when compared to calcite?


The water came out of the ground undersaturated with respect to aragonite, and only minisculely 0.03 saturated with respect to calcite. Dolomite was saturated to the tune of 0.14.

By the end of the stream run, aragonite saturation had increased to 0.7 (max 0.73), calcite saturation had increased to 0.83 (max 0.88) and dolomite to 2.08 (max 2.12). All the maxes were at the next to last sampling station. I would have expected the saturation indices to continue to decrease, but we ran out of stream (tributary to a river). The max saturations were also where the stream was the steepest and the most tufa was being laid down.

My supposition re Mg followed the findings of Dr. Robert Folk, who has some work to the effect that a higher ratio of Mg to Ca than existed in this stream would have to be present in order for dolomite deposition to occur--hence dolomitization occurring in certain Mg rich ocean basins, and through the infusion of seawater through limestone, which does not typically occur in freshwater basins.

What's interesting is the next valley over has a surface stream with aragonite saturation of 0.39, and calcite saturation of 0.53, but this stream is not depositing tufa.
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Postby Squirrel Girl » Apr 9, 2007 11:51 am

I got to thinking, somewhere at home I have a picture of Agua el Hierve in Oaxaca, Mexico. But it's a slide, undigitized, probably. So I googled it, and here's a nice shot.
(besides, there's a guy mooning at the top of my shot :whistle: )

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Postby Jonathan » Apr 10, 2007 3:51 pm

someone said havasu falls...

i've been there a few times, back in the day... i remember mooney falls (the one below havasu falls) to have more "flowstone"/travertine. its a pretty crazy sight to see.

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