The Lithosphere Flashcards
Define mineral
a solid, naturally occurring inorganic substance, with a definite physical and chemical structure
Define resource
a stock or supply of materials
What is sedimentary rock?
rock that has formed through the deposition and solidification of sediment
What is igneous rock?
rock that is formed through the cooling and solidification of magma or lava
What is metamorphic rock?
starts as one type of rock, over time due to heat and pressure changes into a new type of rock
Examples of sedimentary rock
sandstone
limestone
chalk
clay
Examples of igneous rock
basalt
granite
obsidian
Examples of metamorphic rock
marble
slate
soapstone
How do igneous and metamorphic rocks become sedimentary?
weathering and erosion
deposition
How do sedimentary and metamorphic rocks become igneous?
melt
subduction
How do sedimentary and igneous rocks become metamorphic?
heat and pressure
Sedimentary rocks and processes: proterozoic marine sediments
iron ions present in oceans
iron ions react with O2 to form iron oxides
iron oxides form deposits on ocean floor
Sedimentary rocks and processes: alluvial deposits
rivers with high energy and velocity carry lots of sediment
as energy and velocity decrease, sediments drop out of solution and are deposited based on mass and density
Sedimentary rocks and processes: secondary enrichment
metal ore (e.g. copper) exposed to oxygen and water at surface
metal oxidises and goes into solution
water percolates downwards until it reaches water table
metal reduces and precipitates out of solution
copper is concentrated just below water table
Sedimentary rocks and processes: evaporites
water contains salts
water evaporates
salt precipitates on land
Sedimentary rocks and processes: biological deposits
over time, remains of living organisms lithify
What is coal formed from?
terrestrial vegetation
What is oil formed from?
microscopic marine organisms
What is limestone and chalk formed from?
remains of shells of marine organisms
How are granite batholiths formed?
large volume of magma moves up through the earth’s crust
cools and solidifies to form granite
Explain hydrothermal deposition
hot magma rises through lithosphere
water in surrounding rocks is heater
metals and minerals go into solution
hot water moves away from magma, fracturing the rock
water cools
metals and minerals precipitate out of solution
Explain how slate is formed
shale undergoes heat and pressure
Explain how marble is formed
limestone undergoes heat and pressure
Define reserve
deposits of natural resources that can be extracted and exploited profitably with current technology
Define stock
all material in lithosphere (reserve and resource)
Define resource
all the material we can extract from earth’s surface
Why might reserves increase or decrease?
changes in market value
changes in costs
changes in demand
changes in technology and availability
What is an inferred reserve?
presence of a mineral can be predicted from knowledge of geological structures
amount cannot be estimatedWH
What is a probable reserve?
sufficient information about the deposit is known so further exploration is justified
What is a proven reserve?
sufficient exploration to accurately estimate the amount of the mineral that can be economically extracted
What does Lasky’s principle state?
as the purity of a mineral decreases, the amount of the mineral present increases exponentially
What is the cut off ore grade?
the grade of material that has been set as the minimum grade that can be extracted to make a profit
Survey techniques: IR spectroscopy
earth’s surface emits IR
different materials emit IR at different wavelengths
Survey techniques: gravimetry
measures gravitational pull
higher reading = higher density of materials
Survey techniques: magnetometry
detects rocks that are magnetic
cobalt, nickel, iron
Survey techniques: seismic surveys
produce artificial seismic waves
reflected by different layers of rocks
estimate depth and location of deposit
Survey techniques: resistivity
electric current passed between two probes
low resistivity = metals present
Survey techniques: trial drilling
physically collects a sample of rock
confirms presence
Survey techniques: chemical analysis
send trial drilled sample to lab
determines purity of ore
Factors that affect the viability of mining: location to infrastructure
closer = cheaper
Factors that affect the viability of mining: depth
higher = easier
surface mining = cheaper
Factors that affect the viability of mining: purity
Lasky’s principle
must meet cut off ore grade
Factors that affect the viability of mining: hydrology
below water table = mine floods = high cost
Factors that affect the viability of mining: chemical form
pure ores = lower processing cost
determines economic viability
Factors that affect the viability of mining: availability of technologies
determines depth we can dig
development = increase in reserve
Factors that affect the viability of mining: transport costs
higher cost = lower viability
Factors that affect the viability of mining: market economics
stable value = higher mine viability
Environmental impacts of mineral exploitation and reduction methods: exploration
disturbs wildlife
assess organisms present before surveying
Environmental impacts of mineral exploitation and reduction methods: habitat loss
reduced biodiversity
local extinction
habitat fragmentation
recreates habitat elsewhere
trap and relocation organisms
Environmental impacts of mineral exploitation and reduction methods: loss of amenity
reduced biodiversity
return land to original use after mining
Environmental impacts of mineral exploitation and reduction methods: air pollution
dust
CO2 released by fossil fuel combustion for energy
carbon capture and storage
water sprays around mines
Environmental impacts of mineral exploitation and reduction methods: noise pollution
migration
changes interactions between organisms
timing restrictions
acoustic barriers
Environmental impacts of mineral exploitation and reduction methods: increased turbidity
pollutes water
sedimentation tanks
Environmental impacts of mineral exploitation and reduction methods: toxic leachate
toxic to living organisms
divert and treat
neutralise using limestone
Environmental impacts of mineral exploitation and reduction methods: spoil disposal
contains toxic leachate
return spoil to the ground
improve spoil heap
Environmental impacts of mineral exploitation and reduction methods: transport nuisance
noise and dust pollution
time restrictions
restricted routes and access
Environmental impacts of mineral exploitation and reduction methods: flooding
restrict and divert abstracted water
Environmental impacts of mineral exploitation and reduction methods: subsidence
collapse of the ground
return spoils to the ground
use void for carbon capture and storage
Mine site restoration: The Eden Project
reclaimed china clay pit
all water used is sanitised rain water
energy comes from wind turbines in cornwall
How can we extend the time that existing reserves can be exploited?
place restrictions on the amount of materials we extract
improve technology
recycling existing materials
Improved exploitation of low grade deposits: bioleaching
bacteria are mixed with low grade ore - carries out chemical reactions
metal ore goes into solution - produces a leachate
leachate is collected
Improved exploitation of low grade deposits: phytomining
mining metals using plants
plants concentrate metals in their tissues
Improved exploitation of low grade deposits: iron displacement
iron displaced oxidised metal
Improved exploitation of low grade deposits: leachate collection
metal ions removed from leachate via electrolysis
Improved exploitation of low grade deposits: polymer adsorption
positively charged uranium adsorbs to polymer strands
What is a deep sea polymetallic nodule?
mineral concretions on the sea bottom formed from concentric layers of iron and manganese hydroxides around a core
How can we extract polymetallic nodules?
vacuums dredge large swaths from seafloor
hydraulic pumps and hose systems bring nodules to surface
Environmental impacts of deep sea mining
increased turbidity
habitat loss
compaction of sea floor
disrupts aquatic life
Advantages of recycling
saves energy
saves money
creates jobs
reduces landfill waste
protects ecosystems
Disadvantages of recycling
can cause pollution
high initial costs
complex sorting and processing
takes up large amounts of space to store
What is meant by the term cradle to cradle design?
all materials remain in a continuous cycle of use
