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Lecture 9

Lecture 9

Environmental Science
Course Code
Nick Eyles

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20th March 2009
1. Resources vs. reserves
2. d}v]]vP}(v[u]vo}µ
3. Greenstone belts on the Canadian shield: VMS deposits (volcanogenic massive sulphides):
copper, silver
4. Sudbury meteorite crater: nickel
5. Oil, gas, coal, tar sands & evaporates in sedimentary basins
6. Diamonds and hot spots
7. Placer gold in glacial sediments
Resources vs. reserves
- Resources: subeconomic, discovered or undiscovered (known/unknown)
- Reserves: economic, discovered
o Reserves are economically shrinking
o A lot is non-recoverable because it cannot be reached
- Difference between resources/reserves is the cost of the commodity
- Mining
o Chert mining 11,000 years ago in Ontario (oldest)
o William Logan produced the first geology map of Canada
Claimed that there was no coal
Greenstone belts on the Canadian shield
- Pillow basalt - formed under the ocean but end up in the middle of Canadian shield
o Land masses grow (accretion) from protocontinents like Japan into larger continents
- Greenstone belts record waves when they were rising from the ocean
o Most mineral rich rocks in Canada
- Mid ocean ridges: modern analogs for greenstone belt
o Water leeches out the metals that are in the basalt
o Radiate deposits close to the ocean floor
o Minerals accumulate
Volcanogenic massive sulphides
1. Seawater enters ocean floor rocks through cracks
2. Seawater loses oxygen and potassium
3. Water is heated and loses calcium, sulphate and magnesium
4. Hot water picks up sodium, potassium and calcium
5. Water reaches 350C and boil, leaching iron, zinc, sulphur and copper from the surrounding mafic
6. Hot mineral-]ZÁ]}}v(o}}vuP^olu}l_ÁZZÇuÁ]Z
cold oxygen-rich seawater
a. Dissolved metals and sulphur combine to form thick massive sulphide metal deposits
7. /v^ÁZ]u}lU_uo}]o}ÁZ(o}}oZ]vPZÇ}Zuo(oµ]]Z
in the white mineral anhydrite (calcium sulphate)
- Acid mine draining
o Major environmental problem of VMS
o Water going down through rocks and into nearby rivers, draining minerals out of the
- Sudbury basin
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