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Good!  You don't know.  

 

We can agree that you believe there is less than a 1% success in your method of mathematical prospecting.

 

You're all about crunching numbers to pursue your goals, right?

 

How are your results?  What can you teach others?

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Chris and Rod, you guys are spot on.

 

Charles, I enjoy your posts and hope you update some of your other threads soon.

 

***To those who come across this thread in the years to come***  The Airborne Geophysical Surveys the State of Alaska contracts out and then provides to us for free are a great resource.  But beware, when viewing the pretty colors and interesting shapes, locating a viable deposit takes a lot more work.  The surveys are but one small tool in a very big tool chest and should never be the primary source of information when deciding to fund an exploration project, stake claims or worse, buy claims from someone else.

 

Case in point, Donlin is a 39,000,000 (million) ounce AU deposit constrained to a relatively small area.  Within the deposit anomalous AU is in the overburden, quartz veins and sulfides.  A few years ago the State of Alaska contracted out an Airborne Geophysical Survey of the region.  Later they published all the maps that were a product of the survey.  The state also wrote and published an Interpretation report that contained detailed EM Anomaly maps.

 

Question?, "Shouldn't such a large and varied AU deposit stand out like a "Smoking Gun" in at least some of the various maps?"...lets take a look and see.

 

When viewing the various survey maps one could easily come to the conclusion that the area of the Donlin Ultimate Pit is unremarkable...no "Smoking Gun". 

 

Attached are some of the maps referenced, you be the judge.

 

I have overlaid the outline of the Donlin Ultimate pit in each map.  In some maps the pit is outlined in red, in other maps the pit is outlined in black.

 

Tad

 

Ref; Alaska State Geophysical website and Novagold report

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Not quite the response I expected so let me clarify.

 

The beginning of this thread was great, discussing the research approach, availability of data, other methods/tools, opinions...etc.  Somewhere around entry 18-22 we went astray. 

 

Overly touting and defending a specific research method and applying a layman's interpretation above others is well within all of our rights to free speech.  But with any group of semi- intelligent/experienced folks we have to expect someone will have a different opinion and will want to share it.

 

Chris has posted a couple entries in this thread that I believe enables many to envision the totality of the endeavor.  My entry concerning Donlin was not meant to be a dagger into Geo's professional opinion but merely an attempt of identifying an unexpected result (anomaly) from the specifically touted Geophysical method.

 

I am still hoping someone addresses Donlin.  We should remember that more knowledge leads us to more "whys", such as "Why didn't it work?".

 

I hope this thread continues.  I think there is still much to discuss and I know there are others on here that want to learn more.

 

Tad 

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I am always willing to learn more, but we have had a bit of confusion on this thread.

 

The take-away from that is; "Geophysics didn't fail."

 

So that we can all be talking about the same thing, please define what you mean by "Success" and "failure" in the context of geophysical exploration.

If "Success" and "failure" mean totally different things to the folks who are discussing the matter, it can lead to a lot of confusion. So Geo, tell us what you mean by "Success" and "failure" in geophysics.

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Geo...Welcome!

 

OK I had to sleep on what you stated above about Donlin.  In all your math you end up with a one ppm AU figure and state that the AEM survey would not detect that amount of AU but an IP survey would.

 

I thought AEM and IP surveys could not detect gold?

 

I went back and reread chapters 7 and 9 of the NovaGold report on Donlin.  The AU deposit is in dikes and sills with a smaller amount distributed in the surrounding sedentary rock. Some drill intercepts of the dikes, sills and stock works assay as high as 19g/t but the average is around 4g/t.

 

I want to believe that AEMs and other forms of remote sensing will put us on the gold or put an "X" on a map but the more I read case studies, such as Donlin, the reality is it takes a combined approach where additional methods mentioned by other posters on this thread are employed and carry more weight. (no pun intended)

 

Your thoughts....

 

 

T

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I think using the Donlin project as an example in this thread is a good idea. 

 

As far as I can tell, none of us has a vested financially interest in the project. Also based on the publicly available NovaGold report, the deposit is possibly open to an unknown extent north and east of the current claims and leases.  Just maybe we could collectively refine a prospecting method to identifying interesting areas just outside of the Donlin project. Not for our own personal profit mind you, but for the benefit of those who will visit this forum in the future as they seek to understand what it takes to prospect in a modern educated manner.

 

I for one would like to step back slightly from focusing the current debate solely on the role that AEMs play when looking for "buried treasure" (valuable-viable deposit) and take a closer look at some of the other clues mentioned by Chris. 

 

For a couple years I have used the Geochemical dbase the State of Alaska maintains as a research reference and was curious if others here do as well and if they find it usefull.  I am curious what others think about the dbase and if there are limitations in the data provided.

 

I really like the way you can download portions (or all) of the dbase as a Goggle Earth file and save it for future use.  Does anyone else do this, or does anyone want to know how to do it?

 

T

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Excellent explanation in post 65, I had read about Magnetite Suppression before but did not understand the extent it would effect the measurements.

 

Thanks for the info on the "Exploration Models..."  Had not seen that before so I am going to follow-up on some of the projects listed, interesting stuff!!

 

Concerning the GeoChem dbase and assay results.  I have seen a couple where the AU PPM were over 500.  Seems like they were concentrate samples that had been screened to 80 mesh prior to the two methods used.  Due to the screening I would think the "nugget effect" is avoided.  What are your thoughts when you see results like that?

 

Looking forward to your "X" marks the spot info.

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