Sedimentary Geology Geos 240

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Sedimentary GeologyGeos 240 Chapter
8Depositional EnvironmentsPart 5Shallow
Carbonates Evaporites

• Dr. Tark Hamilton
• Readings from Sediments Basins (81-67)
• Camosun College

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Bahamas Platform Fringing Reefs
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La Habana
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Transgression Optimal Carbonate Factory
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Continental Shelf Eastern Nicaragua
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Florida Keys Shallow Back Reef Lagoon
Mangrove Swamps
20 km
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The Great Barrier Reef Cretaceous through
Recent! Queensland OZ
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Lateral Progradation Bahamas Bank
Reflection Seismic Section Interpretation
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Cross Section of Redwater Reef, Dev.NW of
Edmontonflexed later
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Devonian Reef, Gyrfalcon Bluff, Banks Is
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Devonian Crinoid Reef, Princess Royal Is
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Fossiliferous Producing Dev Kee Scarp Reef Norman
Wells
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Devonian Coral Reef, Norman Wells NWT
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Dev. Reef Dolomite/Stromotoporoid Norman Wells
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Ordovician Bioherm, Niagara Falls
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Devonian Reef Dolomitized StromotoporoidCairns
Formation, Grassi Lakes Reef, Canmore
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Devonian Reef Dolomitized StromotoporoidCairns
Formation, Grassi Lakes Reef, Canmore
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Devonian Reef Dolomitized StromotoporoidCairns
Formation, Grassi Lakes Reef, Canmore
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Proterozoic Stromatolites, Dismal Lakes NWT
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Silurian Stromatolites, Somerset Island NWT
Supertenuous Drape
Tidal Scour
Algal Mound Buildup
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Sabkha DepositionalModel, Persian GulfArid Tidal
Coast
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Ancient Tidal Limestone Facies
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Mississippian Lisburne Limestone Tidal Crossbeds
Diagenetic Chert
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Ordovician Intraclast Dolomite Breccia, Somerset
Is. NWT
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Silurian Ripples Flasers Dolomites, Somerset
Is. NWT
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The New Conservative Ordovician Burrow Mottled
Limestone Ottawa
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Ordovician Tyndall Stone, Burrow Mottled
Dolomite, Red River Fm Manitoba
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Ripups Scours Silurian Dolomites, Somerset Is.
NWT
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Transgressive Phase Rising System Tract
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Seds can come from Out of plane
Regressive Phase Falling System Tract
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C-Ord. Cow Head Turbidites, NF
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C-Ord. Cow Head Debris Flow, NF
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C-Ord. Cow Head Deformed Clast
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Exhumed Carboniferous Facies TransitionSverdrup
Basin, Ellesmere Island
Sverdrup Basin Rim
Bioclastic Debrites
Anhydrite, Shale, Detrital Carbonates
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Evaporites Evaporite Basins

• Geographically Enclosed Water Bodies
• Tropics /- 30 Latitude, descending dry air
• Sabkhas, Playas, Salinas, Salt Lakes
• Incipient Rift Basins Triassic Margins of
  Atlantic
• Restricted Back Reef Basins Carbs Anhydrite
• Evaporated Cratonic/Epicontinental Seas Devonian
  of Alberta, Sask., Michigan Zechstein Perm/Penn
  of North Sea Basin
• Often alternate climatically with humid clastics

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Usiglios Experiment Evaporation of Sea Water
Sequence of Salts
s.g. 1.035
Calcite
Anhydrite
Halite
Bitterns
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Development of Evaporite Basin
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Development of Evaporite Basin
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Evaporite Minerals

• Dominant Evaporite Minerals include Carbonates,
  Chlorides, Sulphates, Borates Nitrates
• Marine systems dominantly produce Carbonates,
  Chlorides Sulphates
• Arid Terrestrial Systems produce unusual
  diagenetic minerals in pore spaces and beds of
  Borates Nitrates additional to the Carbonates,
  Chlorides Sulphates.
• Additional to the unusual Continental anion
  Chemistry, salts of metals form some unusual
  brine minerals, Cu, Ni, Zn, Pb, Ag and even
  (NH4) !
• Salts precipitate in inverse order depending on
  their solubility. (solubility in strong/odd
  brines is empirical)
• Salts in vadose zone porosity are important in
  soils

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Textures in Resedimented Evaporites,
ItalyMessinian (5Ma) Mediterranean Basin
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Evaporite Minerals

• Carbonates
• Mineral Formula
• Calcite CaCO3
• Dolomite CaMg (CO3 )2
• Siderite FeCO3
• Natrite Na2CO3 Natron6(H2O)
• Trona Na3(CO3)(HCO3)2(H2O)
• (Green River, WY Lake Magadi, Kenya)

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Carbonate Minerals
Trona
Natrite
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Sandstone with Cubic Halite CastsJurassic, Utah
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Evaporite Minerals

• Chlorides
• Mineral Formula
• Halite NaCl
• Sylvite KCl
• Carnallite KMgCl3 ? 6H2O

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Chloride Minerals
Sylvite
Halite Hopper Crystals
Carnallite
Halite
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Cyclic Crossbedded Devonian Halite, Goderich ON
In what kind of Basin would Cyclic Halite beds
form?
In what sort of flow regime would Halite X-beds
form?
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Evaporite Minerals

• Sulphates
• Mineral Formula
• Anhydrite CaSO4
• Gypsum CaSO4? 2H2O
• Langbeinite K2Mg2(SO4)3
• Polyhalite K2Ca2Mg(SO4)4 ? 2H2O
• Kieserite MgSO4? H2O
• Kainite KMg(SO4)Cl ? 3H2O

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Interbedded Gypsum Calcsiltite,Silurian
Somerset Island
?
Solutional Collapse
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Interbedded Anhydrite Shale Ellesmere Island
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Sulphate Minerals
Polyhalite
Langbeinite
Kieserite
Kainite
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Evaporite Minerals

• Nitrates
• Mineral Formula
• Niter KNO3
• Nitratine NaNO3? 2H2O
• Nitrocalcite Ca(NO3)2 ? 4H2O
• Nitrobarite Ba(NO3)2
• Gerhardtite Cu2(NO3)(OH)3

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Nitrate Minerals
Niter
Nitratine
Nitrobarite
Gerhardtite
Nitrocalcite
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Borax MinesDeath Valley CA
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Evaporite Minerals

• Borates
• Mineral Formula
• Boracite Mg3ClB7O13
• Borax Na2B4O72 ? 10H2O
• Colemanite CaB3O4(OH)3 ? 3H2O
• HydroBoracite CaMg B3O4(OH)32 ? 3H2O
• Larderellite (NH4 )B5O6(OH)4
• Tincalconite Na2B4O7 ? 5H2O
• Ulexite NaCaB5O6(OH)6? 5H2O

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Borate Minerals
Boracite
Colemanite
Hydroboracite
Borax
Larderellite
Ulexite
Tincalconite
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Salar de Atacama, Antofagasta Chile
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The End Chapter 8 Part 5!