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39 Cards in this Set
- Front
- Back
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Subduction zones |
Areas where plates overlap and trenches are created
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Spreading zones |
Areas where plates separate and ridges are created |
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Rocks |
Aggregates of minerals |
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Igneous Rocks |
Develop from cooling and solidifying of magma material
Crystallizes at depth - intrusive/plutonic Crystallizes on surface - extrusive/volcanic Hypabyssal - between extrusive and intrusive |
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Metamorphic Rocks |
Pre-existing rocks are re-crystallized by high pressures and temperatures due to burial |
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Sedimentary Rocks |
Pre-existing rocks are eroded and resulting material is transported (by air, more often by water), deposited, buried, and compacted (lithified) |
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Rock Cycle |
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Approximately 95% of Earth's crust is made up of ______________. However, 75% of the surficial rocks are _____________. |
Igneous, sedimentary |
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Magma |
Originates from partial melting of rocks due to various combinations of increased temperature, decreased pressure, or change in chemical composition |
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Aphanitic |
Fine grained texture (small crystals).
Extrusive: large crystals do not have time to grow because of the sudden nature of the events that form aphanitic rocks |
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Phaneritic |
Coarse grained texture
Intrusive: large crystals have time to grow under Earth's surface |
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Porphyritic |
Texture observed in rocks that have at least two minerals with different grain sizes |
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Phenocrysts & Matrix or groundmass |
Large grains in porphyritic rocks = phenocrysts
Finer grains = matrix or groundmass
Formed by two stages of magma cooling: one at depth where phenocrysts form and second on or near surface where matrix crystallize |
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Felsic |
High silica, potassium, sodium. Low calcium, magnesium and iron
FEL = feldspar; SIC = silica
Light colours, low density
Granites, rhyolites |
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Mafic |
Low silica, potassium, sodium. High calcium, magnesium and iron
MA = magnesium; FIC = iron
Dark-coloured, higher density
Gabbros, basalts |
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Intermediate |
Between felsic and mafic
Diorites, andesites |
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Ultramafic |
Very high iron and magnesium content.
Peridotite |
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Most common minerals in igneous rocks are of the ________ class. |
Silicate: 1) Quartz 2) Feldspars (k- & plag) 3) Micas 4) Amphiboles 5) Pyroxenes 6) Olivine Acronym: Queens Feel Mad And Pissy Often |
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Bowen's Reaction Series |
When igneous rocks crystallize, certain minerals develop in the melt before others. These minerals chemically interact with the remaining melt.
Continuous and discontinuous reactions occur simultaneously between minerals and melt |
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Discontinuous Reaction Series |
Minerals which develop vary over a range of temperatures. Early formed minerals interact with the melt to form new ones
Each step represents a very distinct change with creation of a new mineral, so the change is not a smooth continuous flow
Olivine -> Pyroxene -> Amphibole -> Biotite Olive Pits Are Bitter |
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Continuous Reaction Series |
Formed minerals react with the melt and form an isomorphic mineral
Smooth, continuous reaction taking place
Example: plagioclase feldspars change from being Ca-rich at high temperatures to being Na-rich at low temperatures |
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Discontinuous Continuous
Olivine Plagioclase (Ca-rich) | | Pyroxene | | | Amphibole | | | Biotite Plagioclase (Na-rich) |_____________________________| | Orthoclase | Muscovite (white mica) | Quartz
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Crystallization temperature: high (1400 C) at top; low (800 C) at bottom
Mafic at top, intermediate at merge, felsic at bottom |
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___________ is the most common plagioclase in gabbros (mafic igneous rocks) and _________ is the most common plagioclase in granites (felsic igneous rocks) |
Anorthite (CaAlSi2O8) - Ca-rich, mafic Albite (NaAlSi3O8) - Na-rich, felsic |
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Hydrothermal fluids |
Dissolve, transport, precipitate elements and compounds
Integral part of most igneous and metamorphic processes and commonly associated with ore deposits |
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Dehydration |
Release of water which is trapped in a rock but not chemically bound in a mineral (origin of hydrothermal fluids) |
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Devolitization |
When a hydrous mineral breaks down, releasing its water (origin of hydrothermal fluids) |
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Decarbonation |
When a carbonate mineral containing H and O is heated and breaks down (origin of hydrothermal fluids) |
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QAP diagram |
System of naming igneous rocks based on whether rock is intrusive or extrusive and the percentage of mineral present relative to each other |
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Igneous minerals |
Quartz, feldspars (K-feldspar and plagioclase [Na - Ca]), micas, olivines, pyroxenes, amphiboles, feldspathoids, zeolites, |
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Porphyry copper-gold deposits |
Porphyritic = large crystals in a groundmass of fine crystals
Porphyry deposits are most important source of copper and molybdenum. Also major sources of Au, Ag, Sn, Re, W, Pt, Pd, Se
Bulk tonnage, relatively low grade deposits (typically 0.5 - 2% Cu, 0.2 - 1 g/t Au, 0.02 - 0.06% Mo)
Formed as a result of ocean-continental plate collisions. Pacific rim hosts majority of world's porphyry Cu deposits |
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Porphry Cu deposits in Canada |
Majority in BC |
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Monzonites |
An intrusive igneous rock composed of approximately equal amounts of plagioclase and alkali feldspar, > 5% quartz
Host porphyry copper-gold deposits |
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Alteration zone |
Periphery of the ore deposit, rocks are broken and altered by escaping fluids from injected igneous rock. Frequently silicified |
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Alkalic Porphyry Deposits |
Hosted in rocks that are saturated in alkali-bearing feldspars
1:1 Au/Cu ratios |
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Calc-alkalic Porphyry Deposits |
Hosted in slightly more Fe-rich rocks and are undersaturated in Alkali feldspars
Cu and and significant concentrations of Mo |
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Hypogene mineralization |
Primary mineralization in an ore deposit as these ore minerals were deposited during formation of the deposit by hydrothermal processes |
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Supergene mineralization |
Secondary processes occurring after initial deposition may form a supergene blanket that overlies the primary mineralization
Often cheaply extractable using acid and biological leach methods, whereas primary Cu ores must be extracted using more expensive processes |
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Sub-types of porphyry Cu deposits (4) |
Cu
Cu-Mo
Cu-Au
Cu-Mo-Au |
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Volcanogenic Massive Sulphide Ore Deposits (VMS) |
Major sources of Zn, Cu, Pb, Ag, Au
Precipitate from hydrothermal fluids on or below the sea floor. Ore minerals: pyrrhotite, chalcopyrite, sphalerite, galena
Significant sources of Co, Sn, Se, Mn, Cd, Bi, Te, Ga, Ge
27% of Canada's Cu production, 49% Zn, 3% Au, 40% Ag, 20% Pb, |
