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Lecture 1

Earth Sciences 1022A/B Lecture Notes - Lecture 1: Talc, Nonconformist, Thrust Fault


Department
Earth Sciences
Course Code
EARTHSCI 1022A/B
Professor
Stephen R Hicock
Lecture
1

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Metals extracted from ore minerals:
• Pyrite – an ore mineral of iron
• Chalcopyrite – an ore mineral of copper (wire)
• Galena – an ore mineral of lead (car batteries)
• Sphalerite – an ore mineral of zinc
• Magnetite – an ore mineral of iron (steel)
Igneous Rocks – rock that has solidified from mainly molten material (magma)
Orthoclase, plagioclase, olivine, pyroxenes, amphiboles, quartz, and mica constitute over 95% of
all igneous rocks (they crystallize according to Bowen’s Reaction Series)
Parent Magma Composition:
Felsic – magmas rich in SILICON and ALUMINUM, produce more quartz, orthoclase and Na-
plagioclase minerals – tend to produce light coloured rocks (granite and rhyolite)
Intermediate – magma composition between felsic and mafic (diorite and andesite)
Mafic – magmas rich in IRON, MAGNESIUM, and CALCIUM produce more olivine, pyroxene,
amphibole, Ca-plagioclase, and tend to produce darker rocks (gabbro and basalt)
Ultramafic – magma produces only
ferromagnesian (Mg, Fe-rich) minerals like pyroxene and olivine (dunite, peridotite, pyroxenite)
Textures of Igneous Rocks:
Phaneritic – interlocking crystals of about equal size that are plainly visible to the unaided eye
Aphantic – interlocking crystals are too small to see without a microscope (rocks appear
structureless)
Porphyritic - >10% of the rock volume comprises large crystals (phenocrysts) surrounded by a
matrix of smaller crystals (groundmass) which may be phaneritic or aphantic
Glassy – non crystalline (amorphous) structure like glass – formed from rapid cooling
Pyroclastic (fragmental) – broken, angular volcanic fragments which may be fused (welded)
together
Origin of Igneous Rocks:
• Intrusive (plutonic) – magma crystallizes slowly, deep below ground surface (rocks tend to be phaneritic)
• Extrusive (volcanic) – magma is extruded onto the ground surface where it becomes lava (rocks tend to
be
glassy or aphantic)
• Hypabyssal – magma forms intrusions at shallow depths (rocks tend to be porphyritic)
Sedimentary Rock – particles of other preexisting rock material from erosion, transportation, deposition,
compaction, cementation etc.
• Hold lots of fossils, oils, gas and coal
• Valuable as construction material/ornamental facing stone Composition:
1. Quartz
2. Carbonate – calcite/dolomite
3. Clay (weathered feldspar)
4. Rock fragments
5. Evaporates – halite/gypsum
6. Decayed plant material (forms coal)
Textures of Sedimentary Rocks:
• Clastic – rock composed of the individual particles that were transported and deposited mechanically
(flowing water, wind, gravity, glacial ice)
o Coarse Grain (conglomerate, breccia)
o Medium Grain (sandstone, arkose)
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