Salt of the Earth (on salt domes and beds)

I would like to get some of the geologists that come here to EvC to educate me on Salt Domes and Salt Glaciers.Where are they found?How big are they?I'm sure that I will have other questions as we go along, but we can start there.Just for my benefit, can we start with Spindletop?Edited by jar, : add to sub-title

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Aslan is not a Tame Lion

Any of our geologists out there?

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Aslan is not a Tame Lion

No geologists home?

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Aslan is not a Tame Lion

It would seem to me as a non-geologist, that there must be slightly more there, so please excuse me if I seem dull or uninformed.First, to get the conditions you describe, it would appear that the water would have to be pretty much enclosed, not flowing, to allow the evaporation to lay down the layer of salt.Is that correct?Second, since we are precipitating salt out of the water, the salt layer would seem to be less than whatever the depth of the water was originally.Is that correct?So based on those two factors, it would seem that several things are needed:

• we need an enclosed body of water, a lake or inland sea.
• we need any outflow from the lake to be less than or equal to any inflow.
• the trapped water must stay relatively undisturbed long enough for the water to evaporate.
  

Is that correct?

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Aslan is not a Tame Lion

But will those show as layers? Okay, that is certainly clearer, evaporation greater than inputs. That was kinda what I was trying (not to effectively) to ask. Okay. But large open bodies such as an ocean or flowing water like a river won't lay down salt beds.Is that correct?So the next question is if it is laid down in layers, what is the likelihood of there being deposits on top of a salt layer?

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Aslan is not a Tame Lion

Okay, so far. Thanks for keeping it simple enough for this old mind.Now I once visited Detroit. Under the city is an old salt mine. The salt bed is hundreds and hundreds of feet thick. The salt bed actually covers something like 170,000 square miles, underlying parts of Michigan, Ontario, Ohio, Pennsylvania, New York and West Virginia.So according to you, the way the salt bed was created was that it was an enclosed body of water where the water evaporated leaving salt.I found a few pictures from there showing the some of the salt: So correct me if I am wrong.Sticking just to the one salt bed, the one lying under Michigan, Ontario, Ohio, Pennsylvania, New York and West Virginia, it appears that what we see is a fairly long series of some enclosed area, inland sea, being flooded, then evaporating, drying up and depositing the salt, only to be inundated again and repeating the process over and over.It does appear to be individual layers as well and that there seems to be repetitions of materials.Is that a reasonable summary?

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Aslan is not a Tame Lion

Great. That makes me feel better.Now again it seems this is a pretty large area, 170,000 square miles, so it would take a while to evaporate all the water of that large an area. Is that a reasonable assumption?Edited by jar, : fix subtitle

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Aslan is not a Tame Lion

Because it is the surface area. The area of deposition would I imagine correspond fairly closely to the surface area. As to volume, we have only an indirect way to estimate that, the depth would I imagine be something greater than the thickness of a given layer of salt.I wonder if it would be possible to work backwards from that to some initial "MINIMUM" depth? There must be some limit to how super saturated water at one atmosphere pressure could be? Could that then give us an estimate of the minimum amount of water that had to be present?

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Aslan is not a Tame Lion

I'm afraid that such calculations are outside my knowledge or ability, but I hope some of our geologists will be able to step up.

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Aslan is not a Tame Lion

Thank you.I found some more pictures from the Detroit area where you can get an idea of the size of the layers at this site since they include people in the pictures. There appear to be hundreds of layers, maybe more, and that they vary between just a few inches and a foot or more thick.So it looks like we are going through many repeating cycles of flooding and then evaporation. Is that reasonable?

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Aslan is not a Tame Lion

Okay, so far check and see if have this right.We have an inland sea that covers about 170,000 square miles, then waiting while all the water evaporates only to have it repeat many, many hundreds of times?So one more question.It seems that the Detroit Salt Mine is now buried under over a thousand feet stuff. That seems like a lot of material.What can you good folk tell me about how that happened?

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Aslan is not a Tame Lion

Is this it?The little gridded dots appear to be pretty classic oil or gas (likely gas) wells. Is that what they are?

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Aslan is not a Tame Lion

Speaking of Road Trip, I need to get up that way one day soon.Okay, if that is the location, then it seems that it was a pretty regular source of water right up to around the turn of the century. Some info here.

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Aslan is not a Tame Lion

Back to Motor City.Not only is the salt buried under over a thousand feet of overburden, it appears that there are actually several beds, each separated by layers of rock. Look herefrom this site.It would seem from those images that what happened is that at times the inland sea disappeared completely so that earth built up over the salt, only at a later date for the process to repeat, not just once but several times.Is that a reasonable explanation?

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Aslan is not a Tame Lion

Well the layers seem to be hundreds of feet thick.What would that mean?

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Aslan is not a Tame Lion