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In the Sierra Nevada mountain range, we have the hard rock mining and the placer.

An ancient river, the Jura, is given credit for much of the placer deposits.

What is the theory of the origin of gold in Arizona?

Were there also ancient rivers that deposited the placers?

In other words, what's up stream?

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Ah, but what are the origins?

Since Az. is quite a ways from major plate boundries,

Are there the ancient rivers and glacier deposition?

Or, is it there because it's there?

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The Colorado River follows a Rift. The southern parts of Cal and AZ are loaded with Gold.

The Reo Grande River Valley is a Rift.

Remember Today and Yesterday are two different Animals.

Edited by homefire
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Most of the gold lodes in Arizona are epithermal veins that filled existing fractures, and adjacent, softer, contact zones.

This is especially true where intrusive granite batholiths have been pushed up. At least, that's what I remember from class

eons ago.

Ben

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Acullay any place 200 miles west of there. The gold band follows the Col River. Here I was thinking we covered this in the other post. "were does gold come From"

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So, there were large gold bearing ancient rivers, any identifying names of these rivers?

I have a map that shows the "theororized" route of some ancient river flows in Calif and Nev.

I may be expanding my hunts to Az next year, that is as retirement allows.

(in the Winter, I cant handle the Az. summer heat.)

I'd kinda like to see what y'all are up to, in person.

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It is now- wasn't before.

YOu read through this very detailed thread?

http://www.nuggetshooter.ipbhost.com/index.php?showtopic=28084&page=10&hl=%2Bgold+%2Bcome+%2Bfrom#entry254737

Since Az. is quite a ways from major plate boundries,

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  • 2 weeks later...

One more question,....

Where does the Chinle formation lie in relation to the Gold bearing gravel strata?

From what I saw some 20 yrs ago, the Chin-Lee would be above the Gold bearing strata.

OR,..... is the Chinle only prominent on the Kaibob Plateau?

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CAn't answer your 1st?. HOwever, there's some refereences below that may help.

Chinle Formation ( according to WIKI) is found in NV, AZ , NM , UT,CO and similar formations occur in TX, OK, KS as the DOCKUM GRoup.

http://pubs.usgs.gov/bul/1308/report.pdf

"Geology and Placer-Gold Deposits of the Jicarilla Mountains, Lincoln County, New Mexico By KENNETH SEGERSTROM and GEORGE E. RYBERG GEOLOGICAL SURVEY BULLETIN 1308 A description of the geologic framework, extent, and grade of placer deposits of the area"

--------------------------------------

and

http://www.icmj.com/article-notloggedin.php?id=1301

"

Gold in the Chinle Formation - May 2004 (Vol. 73, No. 9)
Gold in the Chinle Formation
by Edgar B. Heylmun, PhD

TOC-gold-in-the-chinle-formation.jpgThe Chinle Formation, of Triassic age, underlies about 100,000 square miles in Arizona, Colorado, Nevada, New Mexico, and Utah. It adds to the scenic grandeur of the great Colorado Plateau province, noted for its high cliffs and deep canyons....

................................

https://books.google.com/books?id=JFvwAAAAMAAJ&pg=PA164&lpg=PA164&dq=Chinle+formation++Gold+bearing+gravel&source=bl&ots=aIrPDF8qyq&sig=kELxczvG-L6P8Ze7_xd-FMkF4I0&hl=en&sa=X&ved=0CC8Q6AEwAmoVChMIw6ax15aLxgIVgr6ACh3zQQBi#v=onepage&q=Chinle%20formation%20%20Gold%20bearing%20gravel&f=false

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Thank you for asking the question/starting the topic.

I learned something too, and greatly enjoy finding, reading through these old digitized references online.

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  • 4 weeks later...

Steel Pan Its not necessarily all about where it came from, but the glacial flooding that ground away the hillsides here (Az) too. a lot up in Nv. and Ca. JMO but I could show you some crazy stuff on ancient placers. AzNuggetBob

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That's one thing I was thinking about was the glacial deposits.

You can find just about anything in glacial moranes. (sp?)

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Steel Pan
Here is a rough version and eventually more complete and detailed version as I get time I've been working on for "where does gold come from " thread and may still need some editing. I thought Id share it here too.
Its based on what I've read and personally seen out in the field and jmo. I'm always open to new opinions.

On the subject of glacial flooding.

There have been about five major and many smaller separate glacial periods according to recent science and geologists. varying in lengths of age and size. some ice core sampling has already shown that the ice still in existence today is not from the earliest ice ages. we have a good present day example of glaciers and what they can do in many places including Alaska. and with all the suspected major complete melts and minor melts you have wonder are we in the end of a major melt period? there is also a lot geologic evidence of glacial period flooding. what cause the ice to melt so fast. what caused the catastrophic flooding. I think the grand canyon is a great example of it in more recent times. why, because it shows more signs fast erosion and under cutting by massive flooding, creating cliffs in its history rather than slow gradual erosion resulting in more gental slopes. and more recent uplifting of the Rockies and Sierras etc. has directed it toward the grand canyon, death valley and the gulf of Baja. many new rivers and valleys in Az. have been created by the lifting of the Bradshaws and in some cases diverted and covered by pyroclastic flows from volcanic activity in the area.

I think there where huge northern water filled basins blocked by glacial ice the size of the great lakes until they burst releasing huge catastrophic walls of water. (some even pre-dating some current intrusive mountain ranges we have today) I don't think its the result of a single event. if these basins were large depressions in sedimentary material. once they filled from melting ice they could have undercut the hills containing them from immense surface pressure of the lake creating the flooding. or they may have started as trapped ancient inland oceans and may have been caused flooding triggered by major earth quakes, or asteroid strikes. In my opinion,Many of these huge ancient placers were laid down by glacial flooding, possibly caused by Volcanic eruptions through a glacial Ice cap. I would think that if a large asteroid struck one of the earths major oceans the resulting vaporization and shock waves generated through the earths crust could also have triggered huge floods and volcanic eruptions in the area of the impact as well. many of the signs of these early floods have since been dissolved by general weathering and smaller flooding events into present day drainage's but if you keep a sharp eye out learn what to look for you can still find remnants of the more recent ones on some mountain ridges. I think much of the smaller gold nuggets gathered in the larger floods carried from the upper end of the floods and from the lower drainage's was ground into powder by immense ablation and deposited into large sedimentary alluvial fans or the ocean at the bottom end of these lower main drainage's and the larger gold in the minor higher elevation tribs of the time remained near by their bedrock sources.

That reminds me of an ancient placer I found high up on a hillside in N.E. Nev. the old timers had found it too. the placer cobbles where as round and smooth as goose eggs. almost all cemented in and were primarily quartz,chert, and flint with smaller hematite nuggets as well. no doubt an ancient channel. most of those types of rock weren't even common in that area. The old timers had sunk a shaft along the bedrock in the bottom. the channel only appeared to be about 10' wide. as I hunted into the shaft the nuggets I was finding started out smooth at the portal. The biggest nugget I found in the bottom of the shaft cemented into the caliche was around 3/4 oz. toward the main face.

This is were it got strange or so it seemed at first. after going back to camp and cleaning up the 3/4 oz. nugget it was semi-course. quartz/gold. I'm thinking no way? that nugget should be a smooth slug? and then it dawned on me. there must be a quartz vein in the bottom of the ancient channel bleeding out gold near by. I went back into the tunnel, the main face was caved in with placer gravel. there was a few small drifts but no sign of a quartz vein anywhere in the bottom. It looked like the old timers just gave up. so I went back out and looked at the tailing pile, no sizable broken bedrock. all alluvial cobble. old ancient placer.
another one of those old finds I want to look at again this fall.
AzNuggetBob

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Consider too, Pangea and Gondwana Land.

Kinda like getting down to the basics.

The progression of geologic activity fascinates the 'ell outa me. :reading:

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Many locations here in the Motherlode produce nice smooth river worn Nuggets. Then you can find a very coarse nugget with quartz still attached. Does that mean there can be a local source in addition to the placer? Maybe but most likely is during the last major flood that moved the placer that quartz nugget got smashed and released the rough gold only to settle along with the smoother gold.

I have always felt our river canyons were carved out in a short period of time by numerous catastrophic floods.

Edited by El Dorado
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El D
You could be right,
Now you got me thinking. :89::brows: that 3/4oz speci could have come from a crushed goose egg cobble rather than a vein. I'll tell ya I'd rather be raking down that tailing/throw out pile than digging in that shaft. that stuff is like cement. I had a hard time digging them nuggets out a few inches deep in the floor of the shaft. I didnt see any signs of drill holes or blasting. didnt find any cap frags. last time very little trash but a lot of hot rocks with a VLF and a PI mono. Im taking a PI DD coil this time. I've seen some large smooth goose egg size gold quartz species found before, dont remember where they were found, old placers in Cal. I think. but maybe the old timers lost one or two out into the pile off of their drywashers there?. :) Thanks
AzNuggetBob

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There(were) great amounts of coal being mined, up to 2005 in Black MEsa , by the Navajo.

http://www.sourcewatch.org/index.php/Arizona_and_coal. Closed the plant and now tribe gets pollution credits

http://www.sourcewatch.org/index.php/Black_Mesa_coal_mine

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