Serveys And Sampling Flashcards
What are the 5 types of geophysical surveys
Magnetic
Gravity
Electromagnetic
Radiometric
Seismic
How do magnetic surveys work
Scans the magnetic field of an area to pick up on magnetic ores and rock types eg iron gold and nickel as well as oil and gas exploration.
can be done over a large radius
How do radiometric surveys work
Measure the gamma rays emitted when unstable elements within rocks breakdown
Eg uranium and thorium
How do gravity surveys work?
Gravity meter detects changes on earths gravitational field which correlates to changes in the density of material in the earth.
Eg gold oils and gas
How do seismic methods work
Measures the time taken for sound waves to reflect off underground rock formations to determine rock units present.
Eg oil and gas
How do electromagnetic induction surveys work
Measures the electrical conductivity of a subsurface.
Helps locate underground caves nickel copper oils and gas
What are the two types of sampling used in mineral exploration
Stream sediment sampling
Geochemical soil sampling
How does geochemical soil sampling work
A shallow hole is dug and about 200g of sieved material is collected from 10-15cm bellow the surface. Various samples are taken over a vast grid, with follow up sampling occurring on a smaller scale.
Used for gold exploration in the goldfields
Samples are submitted for gold and arsenic analysis (arsenic is often found with gold)
Used for gold and other base metals
How does stream sediment sampling work
1.5-5kg samples of sediment are collected from the main stream just upstream of branching points. Minerals like copper adhesive to clay particles so samples are seived before sent for analysis.
Useful in filly terrain
what are 4 geophysical survey methods
magnetic - magnetic
gravity - density
radiometric - radioactive elements
electromagnetic - conductivity
