Metal Detecting in an A-Star?

[Geowizard]

Jim,

The State has maps and surveys. Very useful to the prospector!

- Geowizard

[Micropedes1]

If you plan on printing more than a few maps from the Alaska surveys, you should use the HPGL format option that is available. It has higher quality and maybe better resolution. At one time I was printing them in segments using a vinyl plotter and building a very large composite map on an office wall. (Me and the gold mining research got evicted from the spare bedroom by the wife). Since then, I have converted everything to digital files which are then projected onto an 8-foot screen. High resolution satellite imagery looks fantastic when at that scale.

[Geowizard]

Great Idea!

i recently picked up TWO large format HP photo quality (55" format) plotters!
$1200 for a set of ink cartridges...



- Geowizard

[Micropedes1]

OK, EM survey loaded into computer. Printed maps at the standby. Flight lines made by helicopter-towed DIGHEM shows EM anomalies, seems like everywhere. Most are magnetite. Or surfical base metal combinations that may/may not mask precious metal signals. Even those that I KNOW to be precious metal conductors also show high concentrations of iron. It seems impossible to separate or differentiate conductor identities that are in close proximity.

What I am saying is that just because a survey anamoly indicates a high magnetic signature on your stacked channel profile does not mean that you should ignore it completely. One that I checked had marketable quantities of REE’s, many of which are magnetic like ferrous compounds.

[Micropedes1]

I am a chemist by training. I know how to analyze mineral samples using atomic absorption spectroscopy. So, I take mineral samples while in the field over a summer’s prospecting, catalog them, and spend the winter trying to figure out what was there. Inasmuch as I am scratching around in the surface strata while sampling, I am only concerned with the 56K EM data (high frequency = shallow strata).

So, when I discover an interesting EM anamoly that meets my search criteria for magnetic intensity and reflected signal strength (among other things), I only need to record the fiducial location (latitude and longitude). Then while prospecting in warmer weather, I move along the survey flight line using my trusty portable GPS until I am in the correct location. Its almost like a big sign that says “Dig Here”! Only its not quite that easy.

Those flight lines are often on parallel courses with ¼ mile spacing. The anamoly that you are seeking is likely not exactly on the flight line made by the helicopter. It can lie on either side of the flight line, displaced by as much as 600 feet. Now you’re prospecting!! Sometimes there is enough mineral staining to be a dead-giveaway as to location. Dikes and sills tend to dip in a certain direction as dictated by the crustal folding, especially in highly faulted zones, so that only a small portion is exposed. If you are sure that your EM signal came from an outcrop, take a couple of chip samples and move on. Otherwise, you might end up with 50 of them cataloged all the way across both sides of the flight line. Pack them out for later analysis to determine the best location of the anamoly strike. (gives you some place to check and dig deeper next year)

[Micropedes1]

All of that digging and sampling can be a real challenge when you are dangling from the end of a rope on a high-angle talus slope with a rock hammer for a digging tool. Mountain goat country!!!

[Geowizard]

The surveys page;


This is the page that lists all of the Surveys. Next, we will set up and come back to select and download a survey.

- Geowizard

[Geowizard]

Software;

Here's a link to a Viewer:

You need to view data files...

This software will allow the user to establish a project and create a project. With a project loaded, it is possible to view a graphical presentation. The graphic presentation will show anomalies.

- Geowizard

[Geowizard]

After downloading and installing, you are ready to go back to the surveys.

Next, we will select a survey.

- Geowizard

[Geowizard]

Jim,

What area do YOU want to prospect?

- Geowizard