ERTH 2001: Resources

1
ERTH 2001 Resources reference thse notes (CVS
Craig Vaughan Skinner, Resources of the Earth)

• What are resources?
• Resources vs reserves vs ores
• Factors affecting price
• Origin of resources
• Examples
• - petroleum
• - gold

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ERTH 2001 Resources
What are resources?
naturally occurring, non-living, useful
materials renewable vs nonrenewable   most
nonrenewable resources are mineral resources     
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ERTH 2001 Resources
What are resources?
naturally occurring, non-living, useful
materials renewable vs nonrenewable   most
nonrenewable resources are mineral resources     
historical discovery/use of mineral resources
4
ERTH 2001 Resources
What are resources?
naturally occurring, non-living, useful
materials renewable vs nonrenewable   most
nonrenewable resources are mineral
resources    mineral resource .... a
concentration of naturally occurring solid,
liquid, or gaseous material in or on the Earths
crust, in such form and amount that economic
extraction of a commodity from the concentration
is currently or potentially feasible (CVS,
Ch. 1, p.20)  
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ERTH 2001 Resources
What are resources?
mineral resources can be classified according
to   abundance geochemically abundant vs
geochemically scarce use e.g., Fe-alloys, base
metals, precious metals, industrial
materials knowledge identified (demonstrated,
inferred) undiscovered (hypothetical,
speculative)   economics economic, marginally
economic, sub-economic availability available,
unavailable (e.g., technology, ownership) any or
all of these factors could determine whether or
not ..... "economic extraction of a commodity
from the concentration is currently or
potentially feasible"
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ERTH 2001 Resources
Resources vs Reserves vs Ores
Resources .... naturally occurring (useful)
materials .... in such form and amount that
economic extraction of a commodity ..... is
currently or potentially feasible
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ERTH 2001 Resources
Resources vs Reserves vs Ores
Resources .... naturally occurring (useful)
materials .... in such form and amount that
economic extraction of a commodity ..... is
currently or potentially feasible Reserves  ...
"that part of the resource that can be
economically and legally extracted at a given
time (generally meaning today)  
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ERTH 2001 Resources
Resources vs Reserves vs Ores
Resources .... naturally occurring (useful)
materials .... in such form and amount that
economic extraction of a commodity ..... is
currently or potentially feasible Reserves  ...
"that part of the resource that can be
economically and legally extracted at a given
time (generally meaning today)   Ores ...
metal-bearing reserves these terms have
specific meanings in the geological and resource
communities - please try to use them precisely!
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ERTH 2001 Resources
What are resources?
mineral resources can be classified according
to   abundance geochemically abundant vs
geochemically scarce use e.g., Fe-alloys, base
metals, precious metals, industrial
materials knowledge identified (demonstrated,
inferred) undiscovered (hypothetical,
speculative)   economics economic, marginally
economic, sub-economic availability available,
unavailable (e.g., technology, ownership) any or
all of these factors could determine whether or
not ..... "economic extraction ..... is currently
or potentially feasible" i.e. resource vs
reserve
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ERTH 2001 Resources
Resources vs Reserves vs Ores
available vs measured vs indicated vs inferred
reserves
everything else is a resource
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ERTH 2001 Resources
Resources vs Reserves vs Ores
Factors affecting the economic viability of a
specific deposit market price cost of
exploration and development cost of
extraction concentration (grade) accessibility
(e.g., mining, transport) processing (e.g.,
technology, transport) environmental
concerns legal concerns political stability
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ERTH 2001 Resources
Resources vs Reserves vs Ores
available vs measured vs indicated vs inferred
reserves
everything else is a resource
Nova Scotia - where do our offshore petroleum
"resources" fit? how about
gold?
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ERTH 2001 Resources
Nova Scotia - where do our offshore petroleum
"resources" fit? how about
gold?
Finally some positive news about the offshore....
Let the gas dollars flow Headline,
Chronicle-Herald, Friday, 26 Oct 07
700-million Deep Panuke to start production in
2010
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ERTH 2001 Resources
Nova Scotia - where do our offshore petroleum
"resources" fit? how about
gold?
Deep Panuke goes aheadFri. Oct 26 - 447 AM FOR
OBSERVERS of Nova Scotias offshore, it sometimes
seemed that the provinces second offshore
natural gas project would never get off the
drawing board. But that changed yesterday. Early
Thursday morning, EnCana Corporation announced
its board of directors had approved the
700-million Deep Panuke gas project. Deep
Panuke, located near Sable Island, is slated to
start production in three years and is expected
to deliver natural gas to energy-hungry markets
in the U.S. northeast. It is expected to
generate 400 million in royalties for the
provincial treasury over the 13-year lifespan of
the project.
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ERTH 2001 Resources
Resources vs Reserves vs Ores
Factors affecting the economic viability of a
specific deposit
Crude Oil Prices 1972-2001 (CVS Ch. 3)
40
where?
effect of Sept 11 attacks?
what happened in late 1973?
0
effects of political (in)stability and global
economics
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ERTH 2001 Resources
Crude Oil Prices 1978-2007
last week 85.00 29 Oct 07 93.20 31 Oct
07 90.60
11 Sept 2001
http//www.eia.doe.gov/oil_gas/petroleum/info_glan
ce/petroleum.html
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ERTH 2001 Resources
Gold Prices 1971-2007
15 Oct 2007 US 756 31 Oct 2007 US 785
1980
1991
1995
1993
1984
1975
1999
11 Sep 01
1977
http//goldprice.org/gold-price-history.html
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ERTH 2001 Resources
Origin of Resources
Elements Used
Source Atmosphere
Source Earth (minerals and brines)
Source Organisms
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ERTH 2001 Resources
Origin of Resources
Problem   many potentially valuable materials
are present in trace amounts only difficult
or impossible to extract from their host
rocks/minerals   Requires  chemical and/or
mechanical processes, operating in or on the
Earth, that are capable of concentrating
materials based on their chemical or physical
properties source of material of interest energy
(e.g., internal heat, solar heat) to drive these
processes
20
ERTH 2001 Resources
Origin of Resources
Natural concentration mechanisms magmatism metamo
rphism hydrothermal processes sedimentary
processes biological processes weathering evaporat
ion i.e., most geological processes have the
potential to concentrate some resource(s) in some
way(s) (overview in CVS Ch. 2)
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ERTH 2001 Resources
Origin of Resources
Geochemical Cycles natural processing, cycling,
and refining of chemical constituents (e.g.,
carbon, water...)   Rock Cycle transformation of
rock matter into various forms by geological
processes these and other kinds of geological
processes have the potential to concentrate
sparse materials into viable deposits
22
Among the most important chemical properties
leading to fractionation and/or concentration of
elements in nature is the "compatibility" of a
given element in a given geochemical system
ERTH 2001 Resources
Origin of Resources
Properties of materials that can lead to their
concentration in nature    Physical density,
hardness, strength, magnetism ........ Chemical
solubility, ionic potential, geochemical
affinity, stability, (in)compatibility
..........   
Among the most important chemical properties
leading to fractionation and/or concentration of
elements in nature is the "compatibility" of a
given element in a given geochemical system
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ERTH 2001 Resources
Origin of Resources
Chemical compatibility compatible elements
that are readily incorporated into rock-forming
minerals minor and trace elements that resemble
major elements in size, ionic charge, electronic
structure incompatible elements not readily
incorporated into rock-forming minerals minor
and trace elements that differ from major
elements in size, ionic charge, electronic
structure these elements are concentrated in
fluids and melts relative to co-existing solid
phases tend to be mobile when solid rock
interacts with fluid or magma
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ERTH 2001 Resources
Origin of Resources
Natural concentration mechanisms magmatism metamo
rphism hydrothermal processes sedimentary
processes biological processes weathering evaporat
ion a few examples ...... (overview in CVS Ch. 2)
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ERTH 2001 Resources
Origin of Resources
Magmatic crystallisation and fractionation
fractionation compatible elements crystals (e.g.,
Mg, Fe, Ni, Co) incompatible elements magma (e.g.
, Na, K, Rb, Li)
final liquid crystallises at top incompatible
elements concentrated
early crystals settle to bottom compatible
elements concentrated
specific elements concentrated depends on -
composition of magma - types of minerals
crystallising
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ERTH 2001 Resources
Origin of Resources
Magmatic crystallisation and fractionation
Sudbury Igneous Complex - world's largest single
Ni deposit - fractionated basic magma - melting
induced by meteorite impact (astrobleme)
zonation related to magmatic fractionation
Ni concentrated in norite (opx plag - rich
zone) lab sample OM-10 is a norite
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ERTH 2001 Resources
Origin of Resources
Magmatic fluids
fluids released from crystallising pluton - can
form pegmatite or vein deposits or - react with
country rock to form skarn deposits
skarn
skarn
skarn
skarn
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ERTH 2001 Resources
black smokers
Origin of Resources
Hydrothermal metamorphism
requires heat fluid source of metals
deep sea floor (spreading centres)
seawater circulates through fractured oceanic
crust heat supplied by underlying
magma associated with seafloor spreading hot
fluid strips metals from basaltic rocks hot
water emerges at seafloor vents metals
precipitate because of changes in T, pH,
salinity creates massive sulphide deposits (Cu,
Zn, Fe, Pb sulphide minerals)
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ERTH 2001 Resources
Origin of Resources
Hydrothermal metamorphism
requires heat fluid source of metals
continental crust
greisen - mica-rich alteration zone
associated with hydrothermal deposits (flaky)
water derived from crystallising magma or
subsurface water in pore spaces, cracks heat
supplied by underlying magma or geothermal heat
(increasing T with depth) hot water circulates
through host rocks strips metals and other
soluble materials hot water works its way towards
the surface metals precipitate in cracks
(veins) or wall rocks because of changes in T,
pH, salinity creates hydrothermal vein
deposits (Au, Cu, Mo, and many, many others.....)
Nesse Ch. 19
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ERTH 2001 Resources
Origin of Resources
Sedimentary transport
placer deposits - minerals concentrated
because of specific gravity (e.g., gold) or
durability (e.g., diamond)
continental margins - thick accumulations of
sedimentary rocks - both modern and ancient
margins host important deposits of
petroleum and other resources
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ERTH 2001 Resources
gossan - oxidised cap formed by weathering of
underlying mineral deposit (rusty)
Origin of Resources
Weathering
in regions with humid climates, intense leaching
of soil and other surficial deposits can
remnove soluble components, leaving residual
material enriched in insoluble components (e.g.,
Al, Fe, Ni) (laterite deposits)
in arid regions, groundwater circulation and
changes in the water table can lead to subsurface
("supergene") enrichment in metals (e.g., Cu,
Pb, Zn)
Nesse, Ch. 19
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ERTH 2001 Resources
Resources .... naturally occurring (useful)
materials .... in such form and amount that
economic extraction of a commodity ..... is
currently or potentially feasible Reserves  ...
"that part of the resource that can be
economically and legally extracted at a given
time (generally meaning today) Ores ...
metal-bearing reserves these terms have
specific meanings in the geological and resource
communities - please try to use them precisely!
Grade of deposit amount of valuable material
relative to total amount of
ore waste rock that must be mined to
extract it (expressed as , or
g/tonne, etc. depending on type of material)