4.2 Mineral And Ore Prospecting

Question 1

What techniques are used for locating mineral and ore deposits?

Answer 1

1. Magnetic surveys
2. Geological mapping
3. Gravity surveys
4. Soil analysis
5. River water analysis

Question 2

Explain geological mapping

Answer 2

Often the first stage of prospecting
Gathers basic geological information
Discover if further, expensive surveys will potentially find something valuable

Question 3

Explain magnetic anomalies

Answer 3

Measured with magnetometer
Can use in the air, on land or at sea
Iron is magnetic adds to magnetic field creating positive anomaly
Mafic Gabbro dyke contains iron giving positive magnetic anomaly
Granite silicic contains less iron than mafic rocks so weak positive magnetic anomaly
Between faults, less iron in sediment than surroundings mafic basalt - causes negative anomaly

Question 4

Explain ground penetrating radar (GPR)

Answer 4

Sends electromagnetic waves into the ground
The waves then bounce back and are detected
The 2 way travel time of the waves and their amplitude are measured and recorded to interpret features underground

Question 5

What is the impact of gravity

Answer 5

All mass has a gravitational field, determined by density
Ore deposits are v dense if metallic
This causes stronger gravitational field in that location
Drilling is the only way to confirm 100% location of an ore body
Bore holes drilled to find exact extent and size of ore reserve

Question 6

Explain geochemical studies

Answer 6

Rocks at surface are weathered and eroded
Same happens to ore bodies
Sampling soil, river sediments and river water to measure concentration of metals and precious minerals
These can help locate the ore
On an ore map the larger the circle, the higher the concentration of ore

Question 7

What do we learn from soil about the rocks underneath?

Answer 7

Soil is organic matter and broken up rocks

So composition could indicate the type of rocks below

Question 8

What is the most appropriate method of prospecting/extracting concealed iron ore

Answer 8

Magnetic surveys and surface mining

Question 9

Best method of prospecting/extracting limestone

Answer 9

Geological mapping and quarrying

Question 10

Best method of prospecting/extracting oil

Answer 10

Seismic surveys and boreholes