Log in

View Full Version : Question



simkiss2001
02-25-2013, 12:59 PM
What is seismic refraction and how can that help with drilling holes
?

geowizard
02-25-2013, 02:15 PM
simkiss,

Seismic refraction is used to measure the depth to bedrock using sound waves. It can provide an image of the bedrock that shows where channels are located. Channels in the bedrock collected most of the placer gold. That image of where the channel is will tell you where to drill.

I am developing deep reading metal detectors this winter to do the same job. Look at www.arctic-geophysics.com .

- Geowizard

chickenminer
02-25-2013, 02:25 PM
Just another survey tool to map subsurface strata.
The key factor in GeeWiz's response is it helps to tell WHERE to drill.

simkiss2001
02-25-2013, 02:45 PM
sweet i am looking to get that done to my claim instead of digging blind .

geowizard
02-25-2013, 03:22 PM
Keep in mind - you still need to drill with seismic. It only shows where the channel is - not the gold.

Metal detection obviously is different. That's why I recommend the methods outlined at www.arctic-geophysics.com. Their systems are ground contact. Probes are driven into the ground and connected to a computer.

The newer, improved method is electromagnetic which uses coils like a metal detector - but on a larger scale. There are websites that show how electromagnetic exploration is done. We used EM at Ophir this summer visit www.ophir-alaska.com for photos. I was able to define the location of a mineralized monzonite dike that crosses the road and goes into the nugget patch.

- Geowizard

simkiss2001
02-25-2013, 04:26 PM
yeah i have been talking to a company that does the Seismic refraction then they will drill the deepest channels and tell me just about how much per yard or something . so what do you guys charge to do this ?

geowizard
02-25-2013, 06:14 PM
Ron,

I run it on my claims and haven't tried to sell the service. I plan on providing more details in March on this type of exploration system. I am doing testing in AZ (near the Ray mine) and if you are interested, I can take you out on the tests and you can see how it works!

- Geowizard

simkiss2001
02-26-2013, 01:19 PM
that would be pretty cool .

geowizard
02-26-2013, 02:46 PM
This is a metal detector and it responds primarily to large conductors at shallow depth. The advantage is that it will provide a reading of conductive zones having blacksand concentrations. This is excellent for finding paleochannel deposits in meandering creeks and rivers as in Alaska. Also good for buried veins with copper and silver mineralization i.e. Arizona Ray mine peripheral veins.

- Geowizard

Bill Bohan
03-03-2013, 04:51 PM
You use seismic reflection not refraction. And you would need to find velocity/rates through lithologies/soils such as topsoil, muck, frozen muck , thawed gravel, and frozen gravel
Your gravel to bedrock interface might be masked if frozen gravel and bedrock have the same seismic velocities.
Seismic profiling will be pricey and finding an an interpreter will be even pricier.

Keep it simple simon

geowizard
03-04-2013, 05:57 AM
Seismology is based on the Law... :)

It's called "Snells Law". The relationship sin theta1/sin theta2 = velocity1/velocity2 is commonly referred to as Snells Law and is fundamental in deriving other expressions to utilize the reflection and refraction of seismic waves in deducing subsurface relationships.

From: Exploring the Shallow Subsurface, H. Burger, Anne F. Sheehan, and Craig H. Jones (c) 2006

So, it's both reflection and refraction!

Seismologists study the different velocities of all of the possible alluvial conditions including consolidation of the layers of silt, gravel and can estimate very closely the travel times through those layers.

You can finf the above reference on ebay and amazon. It includes a CD with examples of different possible multi layer earth models and you can plug in your own numbers to see what the results are.

Winter months offer an opportunity to find books and read them!

- Geowizard