Sedimentary Geology
Geos 240 – Chapter 8
Depositional Environments
Part 5
Shallow Carbonates & Evaporites
Dr. Tark Hamilton
Readings from Sediments & Basins: (8:1-67)
 Camosun College


Bahamas Platform & Fringing Reefs
.
La Habana
Transgression & Optimal Carbonate Factory
Continental Shelf Eastern Nicaragua
Florida Keys: Shallow Back Reef – Lagoon –
Mangrove Swamps
20 km
The Great Barrier Reef: Cretaceous
through Recent! Queensland OZ
Lateral Progradation Bahamas Bank
Reflection Seismic Section & Interpretation
Cross
Section of
Redwater
Reef, Dev.
NW of
Edmonton
flexed later
Devonian Reef, Gyrfalcon Bluff, Banks Is
Devonian Crinoid Reef, Princess Royal Is
Fossiliferous Producing Dev Kee Scarp Reef Norman Wells
Devonian Coral Reef, Norman Wells NWT
Dev. Reef: Dolomite/Stromotoporoid Norman Wells
Ordovician Bioherm, Niagara Falls
Devonian Reef: Dolomitized Stromotoporoid
Cairns Formation, Grassi Lakes Reef, Canmore
Devonian Reef: Dolomitized Stromotoporoid
Cairns Formation, Grassi Lakes Reef, Canmore
Devonian Reef: Dolomitized Stromotoporoid
Cairns Formation, Grassi Lakes Reef, Canmore
Proterozoic Stromatolites, Dismal Lakes NWT
Silurian Stromatolites, Somerset Island NWT
Supertenuous
Drape
Tidal Scour
Algal Mound
Buildup
Sabkha
Depositional
Model,
Persian Gulf
Arid Tidal
Coast
Ancient Tidal
Limestone Facies
Mississippian Lisburne Limestone Tidal Crossbeds Diagenetic Chert
Ordovician Intraclast Dolomite Breccia, Somerset Is. NWT
Silurian Ripples & Flasers Dolomites, Somerset Is. NWT
The New Conservative Ordovician Burrow Mottled Limestone Ottawa
Ordovician Tyndall Stone, Burrow Mottled Dolomite, Red River Fm Manitoba
Ripups & Scours Silurian Dolomites, Somerset Is. NWT
Transgressive Phase
Rising System Tract
Seds can come from
Out of plane
Regressive Phase
Falling System Tract
C-Ord. Cow Head Turbidites, NF
C-Ord. Cow Head Debris Flow, NF
C-Ord. Cow Head Deformed Clast
Exhumed Carboniferous Facies Transition
Sverdrup Basin, Ellesmere Island
Sverdrup Basin Rim
Bioclastic Debrites
Anhydrite, Shale, Detrital Carbonates
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: Carb’s + Anhydrite
Evaporated Cratonic/Epicontinental Seas:
Devonian of Alberta, Sask., Michigan &
Zechstein Perm/Penn of North Sea Basin
Often alternate climatically with humid clastics
Usiglio’s Experiment: Evaporation of Sea
Water & Sequence of Salts
s.g. = 1.035
Calcite
Anhydrite
Halite
Bitterns
Development of Evaporite Basin
Development of Evaporite Basin
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
Textures in Resedimented Evaporites, Italy
Messinian (~5Ma) Mediterranean Basin
Evaporite Minerals
 Carbonates:
 Mineral
Formula
 Calcite
CaCO3
 Dolomite
CaMg (CO3 )2
 Siderite
FeCO3
 Natrite
Na2CO3 & Natron•6(H2O)
 Trona
Na3(CO3)(HCO3)•2(H2O)
 (Green River, WY; Lake Magadi, Kenya)
Carbonate Minerals
Trona
Natrite
Sandstone with Cubic Halite Casts
Jurassic, Utah
Evaporite Minerals
 Chlorides:
 Mineral
 Halite
 Sylvite
 Carnallite
Formula
NaCl
KCl
KMgCl3 · 6H2O
Chloride Minerals
Sylvite
Halite
Hopper
Crystals
Carnallite
Halite
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?
Evaporite Minerals
 Sulphates:
 Mineral
Formula
 Anhydrite
CaSO4
CaSO4· 2H2O
K2Mg2(SO4)3
K2Ca2Mg(SO4)4 · 2H2O
MgSO4· H2O
KMg(SO4)Cl · 3H2O
 Gypsum
 Langbeinite
 Polyhalite
 Kieserite
 Kainite
Interbedded Gypsum & Calcsiltite,
Silurian Somerset Island
?
Solutional Collapse
Interbedded Anhydrite & Shale Ellesmere Island
Sulphate Minerals
Polyhalite
Langbeinite
Kieserite
Kainite
Evaporite Minerals
 Nitrates:
 Mineral
Formula
 Niter
KNO3
NaNO3· 2H2O
Ca(NO3)2 · 4H2O
Ba(NO3)2
Cu2(NO3)(OH)3
 Nitratine
 Nitrocalcite
 Nitrobarite
 Gerhardtite
Nitrate Minerals
Nitratine
Niter
Nitrobarite
Nitrocalcite
Gerhardtite
Borax Mines
Death Valley CA
Evaporite Minerals
 Borates:
 Mineral
 Boracite
Formula
Mg3[ClB7O13 ]
 Borax
Na2[B4O7]2 · 10H2O
 Colemanite
Ca[B3O4(OH)3] · 3H2O
 HydroBoracite CaMg [B3O4(OH)3]2 · 3H2O
 Larderellite
(NH4 )B5O6(OH)4
 Tincalconite
Na2[B4O7] · 5H2O
 Ulexite
NaCa[B5O6(OH)6]· 5H2O
Boracite
Borate Minerals
Colemanite
Hydroboracite
Borax
Larderellite
Tincalconite
Ulexite
Salar de Atacama, Antofagasta Chile
The End: Chapter 8 Part 5!