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Author Topic: Sources of pumice in local argillite?  (Read 1263 times)

Offline OokieWonderslug

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Sources of pumice in local argillite?
« on: 02/08/2014 02:44:14 »
For a long time I had though that the source of the tuff rock here in the Union County area of NC  was due to the volcano became Morrow Mtn. And that still may be the case. But after moving to Stanly County I have had the chance to look more closely. The magma erupted through the argilite layer. It was already there before Morrow Mtn ever existed. The argillite is part of the breccia  made by the magma that became Morrow Mtn.

When I put the argillite in a tumbler and tumbled it I found little salt crystal sized bits of pumice. It is very evident that those grains of pumice did not come from Morrow Mtn. There is no apparent evidence of any other volcanoes in NC that I can find.

So where did the pumice come from? I have been told that any volcanoes have eroded away while softer rock is still here. That makes no sense. There should be an outcrop of basalt somewhere other than Stanly Co area and other than basalt found in those cracks made when Africa pulled away from north America. I have even searched Africa for evidence of a volcano and there is nothing there but sand.

Where did the pumice come from? Is there any way to match the chemical composition to it's parent? There is a missing extinct volcano in nc somewhere. I want to find it. Or at least learn the source of this material.


 

Offline Bass

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Re: Sources of pumice in local argillite?
« Reply #1 on: 05/08/2014 04:05:27 »
OW- Is the pumice that you find in the argillite basalt, or is it lighter colored?  Most pumice and ash is from more silicic volcanoes and can be carried great distances by volcanic eruptions, winds, mudflows and rivers.  There are as layers that can be traced hundreds of miles to more recent volcanoes. The volcano you are looking for may be near or far, may be metamorphosed or may have been rifted away from America in the Triassic. If the particles are in argillites (I assume part of the slate belt), then it is likely that the volcano was eroded and that the volcanic roots (plutonic rocks) may be all that is left.
 

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Re: Sources of pumice in local argillite?
« Reply #1 on: 05/08/2014 04:05:27 »

 

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