Introducing the Gyro Separator Corbus 7000!

Magazine

Ask The Experts

Ask The Experts - Can a detonation help determine the size and location of basalt?

Q: There is an outcrop of greenstone basalt in granite I saw at an elevation of 4,300 feet. Next to it is a chlorite schist outcrop and a mafic ore outcrop. Along the east-west fault for about 100 yards is a green porphyry and at approximately 2,000 feet is a clay-sandstone upthrust that when deteriorated turns green. Along this fault, greenstone basalt debris can be found including a large basaltic boulder over the sandstone.

If the basalt originates at sea floor does that mean it rose at least 4,300 feet and could extend vertically intact that distance above sea level? The next question would be if a detonation in the basalt could send sensory detectable signals to give its size and location as done with petroleum exploration? Thank you for your time.
   Joe

A: While a lot of greenstone metamorphosed basalt was originally formed on the ocean floor, any basalt, no matter where it was originally formed, if it is subject to the right types of heat and pressure, will end up as the same greenstone metamorphosed basalt. Your observation that the forces of the earth’s plates moving around has pushed up mountain ranges is certainly true. The plates moving past each other also scrape off material from one plate onto another. The Pacific Plate has been pushing stuff onto the North American continent for a long time. That’s how rocks formed deep in the Pacific Ocean ended up on the tops of mountains in central Nevada.

One other thing to note is that the effect of weathering on the surface of the ground can change the appearance of many types of rocks. Greenstone metamorphosed basalt will weather to other appearances.

Seismic exploration using a small detonation blast to determine the depth and types of bedrock down in the ground has been used for decades in the petroleum industry, but is only now coming into common use in metals exploration. You are correct that this technique can be used to determine the location of faults and contact of different types of rock. It has the advantage that seismic exploration can often see deeper than other geophysical techniques.

© ICMJ's Prospecting and Mining Journal, CMJ Inc.
Next Article »« Previous Article

Add a Comment

Additional articles that might interest you...

Ask The Experts—How do you amend a placer claim?


Q: How do you amend a placer claim?

Ask The Experts: Sulfides and fluxes


The concentrate is just the heaviest of the heavy minerals but some sulfides are sneaking in there also with the gold...

Ask the Experts


Q: Would a mining company be interested in this area for just the magnetite?

Ask the Experts: Tantalite in an African nation -- is it worth pursuing?


Q: Tantalite in an African nation -- is it worth pursuing?

Ask the Experts


Q: Can you please tell me about diamond fluorescense?

Ask The Experts - How to sell gold specimens


Ask The Experts - Is this a significant cobalt find?


Subscription Required:
The Bawl Mill   • Legislative and Regulatory Update   • Ask The Experts - LR 2000, ArcGIS, and other mapping applications   • Ask The Experts - Advice for a new prospector in Placerville, California?   • Placer Gold Deposits of Utah   • Proven Strategies for Detecting Gold   • Gold Prospecting for Better or Worse: Lesson Learned   • Resurrecting An Old Hard Rock Mine   • Time to Come Home   • Gold Indicators—What to Look for in the Goldfields   • The Rest of the Story—Detecting With Ray Mills   • Gold and Mining Stocks Will Rebound—But When?   • Melman on Gold & Silver   • Mining Stock Quotes and Mineral & Metal Prices

Free:
On the fence about subscribing? Want to check out a 3D sample issue?   • PLP Update

Advertisements

Garrett Electronics - trusted by real miners & prospectors!
Precious Metals Recovery plants and equipment
Fighting to keep public lands open to the public
Specializing in the processing of precious metal ores!
Watch prospecting shows on your computer right now
Free Online Sample Issue