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Author Topic: Advice welcome on this structure?  (Read 481 times)

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Offline EMC

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Advice welcome on this structure?
« on: December 02, 2017, 04:36:25 AM »
Hello,

I have been researching an area I would like to prospect.
I noticed a series of faults on the geo map all parallel with each other three of them, I then confirmed these faults detailed on the geo map correspond exactly with the favorable bearing of the gold associated faults for the area. Following that I then found some information of a 30 gram nugget being found in the river.. What's interesting is the location noted for the nugget falls directly into my corridor depicted by the three faults on the geo map.

So to be clear I have three lines on a map following the bearing of the faults. Where the river cuts through this corridor, we have nuggets being found. When looking at the area trying to get a feel for the lie of the land I noticed this vertical looking structure. The rocks detailed in the image almost are in perfect situation compared to the faults on the geo map.

Is it possible what we see in the image is associated with the faults?
And can I detect right along and up and over the mountains following that compass bearing.
 Following the bearing of the corridor and faults up over the hills there is many eluvial fans on steep slopes many of which in theory should be eroding out material from these structures.

Can anyone please offer some advice?
thanks


Offline EMC

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Re: Advice welcome on this structure?
« Reply #1 on: December 02, 2017, 04:48:02 AM »
Am i completely mistaken assuming this is how the fault could provide gold into the streams and rivers. This drawing does not represent the geology and landscape but it shows how the faults and nug are associated.

Offline EMC

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Re: Advice welcome on this structure?
« Reply #2 on: December 02, 2017, 04:58:52 AM »
The green shaded box shows the active river area to prospect. And the blue shaded box in theory represents area for detecting?? The pink arrow would be looking up the hill at the vertical structure I included in my first post.

My main question;

Is it a good idea to prospect up and over the mountains with a detector considerng nuggets are being found in that green shaded area..

Also is it possible for a feature like we see in the first post to be responsible or part of the process related to gold..

Many thanks in advance.


Offline EMC

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Re: Advice welcome on this structure?
« Reply #3 on: December 02, 2017, 05:02:27 AM »
Or given we know 30 gram was found in the river best stick to prospecting bedrock in likely areas.
This is the first scenario I have come across I can really make a correlation between faults, the visible geology and gold found. And I am just trying to work out how to tackle prospecting the hills. 

Offline EMC

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Re: Advice welcome on this structure?
« Reply #4 on: December 03, 2017, 07:23:20 AM »
Hi EMC. Was the area a glaciated valley or were there no glaciers through the area?

I've also been trying to figure out how the fault could have affected the gold deposits in my area as the fault line is very close and north of my claim.

Is the gold you are finding or others have found very rough and crystalline looking with quartz attached to it?  Like it hasn't traveled far to get to where it is or is it very smooth and worn looking like it has traveled a far distance?
 
Not sure if you can find out geologically if your area went through different periods of mountainous uplifting but if it did that can affect how rivers traveled through the valleys at different time periods. For example where I am mining there are examples in different valleys where the rivers actually flowed in complete different directions than how the current ones do. Not just opposite but also across the current ones. Which proves that the valleys drainages flows were at different elevations and directions previous to how they are now.

I've been contemplating over this past season to try to get some loose talus ore from my fault zone area and some of the gold on my claim radiometric dated to see if they are from the same fault and/or time period or not. If so i could try to pin point more specific areas to explore on my claim for higher gold concentrations. As I have three distinctly different types of gold on my claim I am interpreting that they come from three different sources. Some of the gold is very rough with Lot's of quartz, some is very smooth and traveled far, and some is a very orange with black color with higher amounts of oxidizing minerals in it which do not look like some of the other gold found in different areas on my claim.
The gold you are finding can maybe give you some clues as to where it came from too.

Thank you very much for your response,

So I understand there is no glaciers up stream in the hills. However the area as a whole was involved with glaciers. The 30 gram was a specimen in milky quartz's the actual quartz rock was quite rounded..

"the gold from the area seems to have originated from a vein in NW direction"

Following that bearing there is old mines and a 1.2 kilo specimen supposedly found.

It  appears the gold is coming from the NW in the corridor.

In the actual river its not impossible to find stuff up a cm clean gold well traveled in the cracks.

Offline EMC

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Re: Advice welcome on this structure?
« Reply #5 on: December 03, 2017, 07:34:16 AM »
The fact the 30 gram specimen is very rounded quartz that indicates the quartz has traveled fair. Maybe further than the proposed source area it would seem. Or did it get bounced around that valley for a few hundred/thousands/million years. Or was it moved around by a glacier.

In terms of prospecting the area do I focus on looking for outcrops following the bearing up over the mountain and or sampling the material fans collecting at the tops of valley. I suppose once I get on the hill side I will know more. If I start seeing similar quartz rounded loose on the mountain side I could be getting closer.
I will go to town on researching the old records if any exist try and locate some of the old mines and placer workings.

Offline EMC

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Re: Advice welcome on this structure?
« Reply #6 on: December 03, 2017, 07:46:10 AM »
I have a small rock crusher for sampling likely quartz also a low end VLF detector plus a Falcon MD20 neither of which will give me any chance of detecting a specimen more than a few inches under the ground at best. I was contemplating a second hand gpx. However not sure I appreciate the learning curve required.

Its a difficult one, i cant wash pans on the hill side, didn't plan on packing material out of there, my current detecting set up wont cut it.

I said to my buddy the first specimen we find out the river we cash in for gpx.. (but we may never find it..)

Ultimately further down the line some trip to Aus and maybe Alaska is on the cards. So the sooner we get some practice in on a gpx the better.

What do you think?

I found some great info on this forum regarding prospecting pocket gold.

I have maybe another 6 weeks of research time available before head out there for 2-3 month.

Can anyone recommend a suitable PI machine other than minelab.

 cant wait.  <-yahoo_>
 

Offline poncho

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Re: Advice welcome on this structure?
« Reply #7 on: December 03, 2017, 05:20:51 PM »
Good info Blue Clay
ONWARDS AND UPWARDS

Offline EMC

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Re: Advice welcome on this structure?
« Reply #8 on: December 04, 2017, 04:06:05 AM »
EMC are you trying to find the hard rock location where the gold originates from in order to hard rock mine it or claim it to hold, or are you more interested in trying to find more concentrated areas of placer gold?

Myself I am placer mining so I am first most interested in finding the best concentrations and pay layers of placer gold. But its always in the back of my head trying to get a grasp on where the gold is originating from. For me it's more realistic and important to concentrate on trying to figure out the placer layers in my valley before trying to track down more of an idea where it is coming from. But the hard rock part of it always intrigues me a lot.

Some of the things that helped me get a better grasp of my area are old mining and geologist reports of the area. Some of which talk about how and when the glaciers moved through the area and in which directions, when the mountains uplifted, how to identify which gravel, glacier till, and clay layers are from which time periods, how to identify tertiary channels under those sediment layers, etc, and what types of false and true bedrock there is in the area.
If you can get an idea of how those kinds of things affected your area then they may point you in certain directions in your search.

If you are finding finer gold in the creek then under low water conditions, walk the creek and look for the largest boulders you can and preferably on inside bends and even better if they are on the inside "exiting" bend of the river.
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Dig under those largest boulders. If you find fine gold in cracks on the river in other locations, you will most likely find bigger gold in the boulder areas on inside bends. Walking the river can also help you identify older dried up channels that used to travel across the valley in different directions than the current creek. Look for a change in rock type and color.
And try to match up different geology to different time periods. If most of the specimens you've heard about have high amounts of quartz attached then ya I agree look for loose quartz talus trending in certain directions and drainage's.

If it's concentrated placer gold you are looking for then in the valley between the mountains and in current and old drainage paths look for gully depressions. Deep V depressions. All types, shapes of gullies can be great gold traps from past river and glacier travels through the area. Some times Topo maps can identify decent sized depressions well but some of them are less drastic and not as easy to spot. Not sure if any companies have done Lidar imaging in your area before but that's something to look into in your prospecting. Lidar imaging will show you the contours/lay of the land with the trees/vegetation stripped off of the image. It's one of my most valued prospecting tools.

Your tools are very similar to mine while walking the land. I use a Whites GMT and a MD20 and a kit with pan, pick, small pry bar, and shovel and hand made rock crusher at camp. The MD20 can be very effective at doing quick scans of loose talus chunks.  https://www.youtube.com/watch?v=skeOEpcVjXo    If the specimen has decent amount of gold in it you may be surprised how a detector can pick it up even fairly deep down. But yes, I agree, a minelab GPX would also be my next choice when I upgrade. Not sure how well they are though in highly mineralized areas from ground balancing and focusing in on just gold targets while cancelling out the hot rocks.
If or when you do buy a Minelab make sure you look on the internet how to identify Minelab fakes. Apparently there a lot of them out there made in China fakes that look very, very real. You can also call the company with the serial number to confirm if it's authentic. Be really careful buying used or new. I've read even some online stores have been closed for selling the fakes.

Keep us posted on your prospecting and take some pictures on your trips. Those kinds of posts on the forum are very cool to see and are a breath of fresh air for us to check out.

Hi Blue clay,

I am happy your happy to read such posts..

Thank you very much for your explanation. Plenty of food for thought.
Thanks also for your advice regarding purchasing a minelab, I had read caution must be exercised when doing so.

The main objective was to find coarse gold. Be it from the active river or mountain side.
At this point I am investigating all options. So placer and hard rock is in my scope of research.
We are not hard rock miners, have zero experience doing so. But I am greatly interested in broadening our horizons out of the active rivers onto the mountain sides. For me it seems more realistic for something special to have been missed between the source areas and the active rivers.
After noticing a potential correlation between the gold being found and the faults then the history of the mines and the large specimens. I figured it might pay to go in search specimens on the hillside.

(so I understand)
Largely most of the placer gold is associated with paleo-placers.
 Apparently favorable terrain is Paleozoic carbonate and clastic host rocks.
I have read the area has intrusion-related deposits and orogenic deposits.
 
Also i have read that the deposits were created over a short period between 305 and 290 Ma, during the latter stages of collisional tectonics.Intrusion deposits Au-Cu skarns are associated with quartz monzodiorite/monzogranite dating from 297-294 Ma.

Some of the orogenic deposits consist of sheeted quartz-arsenopyrite vein structures.

The area as whole is defined by 4 different individual gold belts..

I am breaking down the geological terminology and learning day by day.
But I struggle to make the connections between the above and what we see in the field. And use the above to my advantage.

I will happily send you all info I have Blue clay on the area in PM if you would be interested in having a look?

For sure I will post some updates as I go with some photos.

Offline EMC

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Re: Advice welcome on this structure?
« Reply #9 on: December 04, 2017, 04:34:39 AM »
I suppose I am doing things the wrong way round a bit. And as you say maybe better trying to understand the placers first. Then study the terrain once we have some knowledge in the field on this spot. The main reason I was looking into this is because the river itself no doubt has been hammered. Its quite a small river and the "hills" are maximum 900m high.  I think exposing bedrock in favourable spots could be the fastest route to some coarse gold.
But it was playing on my mind what may await discovery in difficult access areas on the hill sides.  sunday prospectors I doubt will be scouring the hills with a machete. The vegatation is very dense. So it really is the unkown up in the gullies and gulch. The initial plan was to try and trace some coarse gold up some of the feeder streams for confirmation on the path its taking., then look for relevant gullies and gulch upstream.

A different area Last year I prospected 6km from a 6m wide river all the way up to the top of the mountain. 6 km run from the delta to the top.  300m from the summit the gold just disappears out the pan. At 350m down the stream from the summit you have very angular quartz gold specimens and steep bedrock banks coming down from the mountains with multiple outcrops visible. W e searched and searched for over a week in an area 300m2 but could find no veins showing mineralization. If we buy a gpx I will certainly go back there and spend some time hacking my way through.

We was finding water worn gold with the angular specimens, clean gold, gold-manganese i think.