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Author Topic: WORLD GOLD DEPOSIT MAPS  (Read 75750 times)

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Offline overtheedge

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Re: WORLD GOLD DEPOSIT MAPS
« Reply #10 on: December 19, 2012, 08:20:20 PM »
If you folks are really serious about this craft, I would suggest taking a college course in Physical Geology. Best college course I ever took.

Typically when two tectonic plates have a head on collision, one plate gets crammed under the other plate (subducted). Between the friction and the heat that still exists at depth, the subducted plate partially melts. Rocks, being a bit brittle, get cracked in this collision and the partially melted minerals get squeezed upward into cooler rock just like toothpaste out of a tube.

The interesting part is the subducted plate drags a lot of salt water with it and so this melted material has a higher water content and when it hits different minerals as it gets squeezed upward, a witches brew of chemical reactions take place.

These collisions took place several times over the history of starship earth. Some melted stuff reached the surface as volcanic eruptions, but a lot more was way down deep when it finally refroze.

Bring on several millions of years of erosion and an occasional ice age and the deep deposits finally see the light of day.

For areas that have gotten pretty leveled out by continental glaciers, the larger gold that gets exposed no longer has river courses flowing fast enough to spread the larger gold very far. An example of this is the Canadian shield where Precambrian deposits are exposed.

Hope this brief explanation helps.
eric

Offline ebuyc

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Re: WORLD GOLD DEPOSIT MAPS
« Reply #11 on: December 19, 2012, 09:35:26 PM »
If you folks are really serious about this craft, I would suggest taking a college course in Physical Geology. Best college course I ever took.

Typically when two tectonic plates have a head on collision, one plate gets crammed under the other plate (subducted). Between the friction and the heat that still exists at depth, the subducted plate partially melts. Rocks, being a bit brittle, get cracked in this collision and the partially melted minerals get squeezed upward into cooler rock just like toothpaste out of a tube.

The interesting part is the subducted plate drags a lot of salt water with it and so this melted material has a higher water content and when it hits different minerals as it gets squeezed upward, a witches brew of chemical reactions take place.

These collisions took place several times over the history of starship earth. Some melted stuff reached the surface as volcanic eruptions, but a lot more was way down deep when it finally refroze.

Bring on several millions of years of erosion and an occasional ice age and the deep deposits finally see the light of day.

For areas that have gotten pretty leveled out by continental glaciers, the larger gold that gets exposed no longer has river courses flowing fast enough to spread the larger gold very far. An example of this is the Canadian shield where Precambrian deposits are exposed.

Hope this brief explanation helps.
eric

Yes very helpful.
The plate tectonic squishing is what made the motherlode gold in California. The folding and squeezing created pressures that concentrated huge deposits of gold.
Now in Idaho and Montana the gold was formed more from mineral precipitation like in Yellowstone way back when that concentrated gold but in smaller thinner deposits.
The difference is the pressures were more from the core underneath instead of folding plates.
There is some further concentrating from pressures after the fact due to tectonic shifts and upheavals. That is why the Silver Valley is high in lead, silver (galena), zinc and many more metallic sulfides.
But they have found some big nuggets in the area too. The bigger gold was probably formed more from extreme pressures and chemical reactions like what you mention.
Of course that is how I understand it and I am not presuming to be as educated in this matter kind sir ;) So please feel free to correct me if I am wrong.

Quote
When the road was rebuilt over the dredge spoils in 1997 - 1998, many nuggets were found. Two smaller ones (2+ ounces) found in 1998, are displayed at the CRYSTAL GOLD MINE. More than likely, the finders used metal detectors. (The sellers won't say.) A 7-ounce nugget was found in 1998 by road crews cleaning out a culvert.
Source: murray-idaho.com

I was just gonna color the map a little to make the marked zones pop a little better. I am not going back to school ever, 50K on my education is my limit. I can teach myself faster if I really want to know something. I like ordering books and ebooks ;)

And I especially like reading posts from educated, factual, experienced and to the point person! Thanks again.
I am sure others may find themselves compelled to take some cool geo classes.

My 2 bits...
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Offline Former Guest

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Re: WORLD GOLD DEPOSIT MAPS
« Reply #12 on: December 20, 2012, 09:54:52 AM »
A friend from my hometown gave me all the physical geology books from N,A,I.T.  Its a 2 year course there i have grade 10 slept through grade 9. But with my memory ask my wife numbers come easy to remember for me and have a photo memory this helps here and school was a wast of time for me. Was working full time at 15 years old in the 1070ies school was nothing. Growing up on a farm i got to build many things there. Use many tools and fix things, this is very helpful now. I do study these books and yes the lingo is hard to undesstand subduction zones, mountain building and many things to learn from them. I strongly recommend them to anyone some great reading and explains thing alot better than hersay from ppl. The glossary at the back of text book explains all lingo you cannot understand. Used book stores are great to find these books, or can buy new ones from students that are done with theres for there class. I found these very helpful understanding things you do not understand. Some where its in there start at the first page and go from there some is very booring but plug through it lots to learn from them cheers Ray

Offline Tommyknocker

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Re: WORLD GOLD DEPOSIT MAPS
« Reply #13 on: February 04, 2013, 08:17:32 PM »
Great maps!!! Can you tell me/us the difference between a gold deposit and a gold occurrence?I know what a deposit is but not the difference in regards to this data? Thanks...Tom
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Offline shotgunner78

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Re: WORLD GOLD DEPOSIT MAPS
« Reply #14 on: June 16, 2015, 05:28:40 PM »
nice..thanks

Offline 911Met

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Re: WORLD GOLD DEPOSIT MAPS
« Reply #15 on: September 18, 2015, 04:42:05 AM »
I don't know why am so surprised there'd be placer gold just east of Montreal Quebec Place Gold Deposits -Map | 911M