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Final

GLG207H1 Final: GLG207-ESS222 Exam Study Notes


Department
Earth Sciences
Course Code
ESS102H1
Professor
James Mungall
Study Guide
Final

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ESS222 Exam Study Notes
Sedimentary
Sedimentary Rocks
- particles - clastic sediments
- solutions - chemical sediments
- biogenic material - carbonates, cherts
- cover 65% of land, ~90% of ocean floor
Common Sedimentary Rocks
- sandstone ~25%
- mudrock ~65%
- carbonate ~10%
- others <5%
- conglomerate, chert, evaporite, ironstone, phosphorite
- clastic = fragmental, produced by breaking of rock
- detrital = fragmental, but also transported from source
- breakdown of aluminosilicates (look at reactions)
- breakdown of mafic phases (look at reactions)
- oxidation of Fe2+
- most Fe is Fe2+ in minerals
- during weathering Fe2+ is soluble
- when it meets air it is oxidized to insoluble Fe3+
Soil Formation
- Cold, arid climates
- mechanical breakdown
- poor soils
- humid, warm climates
- weathering to clay
- soil production
- tropical, wet climates
- near complete dissolution
- duricrust production (calcrete, ferricrete)
Sediment Transport and Deposition
- derived from upland areas
- largest clasts move shortest distances
- gravel in high energy environments
- sand in moderate energy
- mid in quiet places
- carbonates where there is no clastic sediment
Mudrocks in Brief
- mud is easily transported

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- will only settle in still water
- mudrocks deposited in large basins
- oceans, lakes, flood plains
- accumulations easily >2km thick
- very large lateral extents
Sandstones in Brief
- sand carried only in rapid currents
- rolling, saltation, suspension
- deposited wherever current slows
- rivers, beaches, marine sandbars, turbidites
Carbonate Rocks (Limestone, Dolomite)
- largely biogenic
- skeletons of macroorganisms (shellfish) or plankton
- some direct inorganic precipitation
- carbonate produced only in the photic zone
- preserved only above the carbonate compensation depth (ccd)
- shallow water sediments
- deposited in clear warm water
Depositional Basins
- sources and traps defined by plate tectonics
- most preserved sediments are marine because oceans:
- are deep
- cover greater area
- exposed continental surface is easily eroded
- largest accumulations at continental margins
Sedimentary Basins
- deep oceans
- arc-trench systems
- continental collisions (flysch, mollasse)
- passive margins
- intracontinental basins
- epicontinental seas
Oceanic Basins

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- deep oceans
- dredged samples
- ancient deposits accreted to continents
- pelagic sediment
- wind blown dust
- planktonic ooze
- distal tips of turbidite fans
Arc-Trench System Basins
Trench
- place where oceanic crust disappears
- deepest basins on earth
- adjacent to volcanic highlands
- rapid turbidite sedimentation onto pelagic sediments
- rapidly tectonized, metamorphosed
- generation of melange complexes
- preserved or exposed by collision or compression
Forearc, Intra-Arc Basins
- sandstones rich in volcanic, plutonic rock and mineral fragments
- shelf, delta, turbidite fans
- preserved or exposed by collision, or by compression of forearc area during subduction
Retroarc (Backarc) Basin
- transitional from arc to continental shelf
- turbidites, volcaniclastic fan from arc
- sands, muds, carbonates from continental margin
- complex stratigraphy
- preserved by arc-continent collision
Continental Collision Basins
- marine basins fed by orogens = flysch
- pinched between continents, eg. Mediterranean
- off to the sides, eg. Bay of Bengal
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