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Fault Lines, How To Find Them?


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We all talk about gold and fault lines BUT how do you go about finding these fault lines exactly? 

They are not shown on Topo maps that I know of. What maps should I be looking to acquire?

What do they look like in person? Sharply uplifted rock areas I am guessing?

-Tom

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I use geological maps to show fault lines, but as a total layman, my geo knowledge is only self taught. A fault line can run along a mountain range, along a flat, a valley etc, I don`t think there is any general topo feature that is characteristic of all fault lines. But quartz is a good indicator in the country I prospect.

Whilst prospecting for new patches I georeference geological maps into Oziexplorer (mapping software) on the PC, transfer these over to a Android smart phone Oziexplorer application. Then using the phones inbuilt GPS allowing me to see exactly where I am in relation to fault lines shown on the map on the phones screen, as I prospect. Makes it much easier then using paper maps, fault lines are most important to me.

To get started grab a geo map of your area that also shows past and existing mines, and check the relationship of these mines with the fault lines. I really don`t know if my approach is correct geology wise, but it works and has for many years.

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Get a good geologic map of your area.

In the field look for changes in rock type, color changes can be reddish or bleached white, look for vein material, breccias, or shattered rock, also springs and seeps are good indicators, oxidation in some cases

Depending on conditions they can form a topographic high if silicified and resistant to erosion, or a low if dominated by crushed rock that is easily eroded.

Here's a couple from Nevada, where all the geology is easily observed.

third photo is silicified  rock in the hanging wall of Comstock fault zone Virginia City

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Where do I even get a geologic map of an area in USA? We don't have any mountains in Illinois and Indiana, only glacial moraines pretty much.

Of course there was the gigantic earthquake back in 1820 something that changed the course of the Illinois river, the New Madrid earthquake as it was called.

The only metals mines were for zinc/galena in extreme NW corner of Illinois, coal mines central parts of both states, sand dunes around Lake Michigan.

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https://mrdata.usgs.gov/geology/state/

Click your state of interest, then if you have Google Earth just download the KMZ and open it up. Or use their web browser link, but GE is way more handy and it also has high res aerial imagery which honestly is much more useful for finding smaller, unmapped faults which are more like what we are after as small scale prospectors.

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Quote

third photo is silicified  rock in the hanging wall of Comstock fault zone Virginia City

The footwall of the Comstock fault in that photo is in the background on a hill that shows a road coming in from the right. The scarp to the left of the end of the road is where a mining company (Houston Oil and Minerals) was mining in the Gold Hill Pit and caused a landslide which slid down along the Comstock fault in the 1980s. 
Consider how wide the Comstock fault zone is if the silicified rock in the foreground is in the hanging wall area (but is not the actual hanging wall) and the footwall is in the background hundreds of yards away.

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Chris,

My info comes from an exploration guide written by Charles Clifton and Larry Buchanan in 1982 (photo 15). Clifton's caption reads "Resistant ledge, hanging wall, Comstock lode, Virginia City,Nevada."

Don't think he was implying it was the hanging wall, but in the hanging wall.

Either way I've never been in a room with more than one geologist (me included) that interpreted things the same way. lol

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I second JasonG.  My preference is to open up .kmz files in google earth.  Certain Garmin GPS will allow you to import images from google earth. this is my preference.   Identifying the faults even when you are right where the map tells you, is still somewhat difficult to me as well.  It would be nice to see a crack or obvious fault like the San Andreas, but i have never found them this way.  I am looking for contact zones of different minerals or dikes created by minerals being forced up through these faults. 

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