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long time and can be reactivated on numerous occasions. This results in individual lenses that are a
hundred meters thick and extend hundred meters along strike. The reactivation also causes the
deposits to be zoned around the black smoker pipe, with a predictable distribution of sulphides.
The massive accumulations of sulphides show up very well in geophysical surveys because they are
both denser and more conductive than the surrounding rock, making VMS deposits a relatively easy
geophysical exploration targets.
The shape of the deposits makes VMS ideal for cheap open-pit mining methods because a large amount
of ore can be removed without having to remove very much waste rock. This is a much cheaper mining
method than when ore is hosted in narrow veins, resulting in a much higher ratio of waste to ore
removal..
VMS deposits often occur in clusters within a particularly small area (~10 km ) all related to the same
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event, since the metal-rich fluids may escape to the surface through many vents. The discovery of one
large VMS deposit may well mean that there are other targets nearby.
Almost any age of terrain can potentially host a VMS deposit. The oldest VMS style deposits are some 3.4
billion years old while the youngest are being deposited today in oceans including the Red Sea and the
western Pacific Ocean. There are ~800 VMS deposits known worldwide with about 350 of those in
Canada. Worldwide there is much exploration for VMS-style deposits, particularly in the remote
Canadian arctic.

Important Deposits
Flin Flon,Manitoba, Canada.

Kidd Mine in Timmins, Ontario, Canada.

The Flin Flon Greenstone Belt are ancient
Precambrian rocks which host the biggest
concentration of VMS deposits in Canada. The
ore bodies are predominantly zinc-copper
with significant gold and silver. Ore bodies
range in size from 100,000 tonnes to 60 million
tonnes.
One of the largest producers is Hudbay
Minerals Inc. that was founded in 1927 to mine
the region. Their 777 Mine produces zinc, copper, gold and silver.

They are currently developing a new project at Snow Lake some 215km north of Flin Flon. In 2012 their
production figures included:
• 39,587 tonnes copper
• 80,866 tonnes zinc
• 101,059 ounces of silver and gold.
Kidd Mine, Timmins, Ontario, Canada
The mine is hosted in the Abitibi greenstone belt which is around 2.8 – 2.6 billion years old Kidd Mine is
operated by Xstrata and is one of the world’s deepest base metal mines. Opened as an open pit mine in
the 1960’s it’s currently mining at 2800m below ground. The main commodities are copper and zinc.

Gravity Surveys

Gravity Surveys – the basics
Gravity surveys measure minute variations in gravity. Gravity at every point on the surface of the earth
varies slightly depending on:
• distance from the equator;

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