Sedimentary Geology Geos 240 – Chapter 8 Depositional Environments Part 1 Introduction, Fluvial & Coastal Dr. Tark Hamilton Dr. Tark Hamilton Readings.

Sedimentary Sedimentary GeologyGeology

Geos 240 – Chapter Geos 240 – Chapter 88

Depositional Depositional EnvironmentsEnvironments

Part 1Part 1Introduction, Fluvial & Introduction, Fluvial &

CoastalCoastal Dr. Tark HamiltonDr. Tark Hamilton

Readings from Sediments & Basins: (8:1-Readings from Sediments & Basins: (8:1-67)67)

Camosun CollegeCamosun College

Great Barrier Back Reef, Great Barrier Back Reef, QueenslandQueensland

Branching Corals & Carbonate Sand

Depositional EnvironmentsDepositional Environments

The Peace River, Ft. St. John, NE B.C.

Four

3

1

2

4

DecreasingGradient:1>2>3>4

Gravel-Sand-Silt-Clay

Sandy Braided River ModelSandy Braided River ModelBased on South Based on South SaskatchewanSaskatchewan

Flow & AggradationLateral Aggradation

Bars Persist for decades

Anastomosed River ModelAnastomosed River ModelBased on Cumberland Based on Cumberland

Marshes,Marshes,East Central Saskatchewan-East Central Saskatchewan-

ManitobaManitoba

Flow Direction, C

hannel Sands

Crevasse Splay Deposit

Stable Vegetated Marsh

Cutbank, Upwards Fining, Cutbank, Upwards Fining, CenozoicCenozoic

Narrow Sand Body, Permian Anastomosed Narrow Sand Body, Permian Anastomosed River, NMRiver, NM

Point Bar Sand with Point Bar Sand with Lateral AccretionLateral Accretion & & Mud FillMud Fill

Cutbank, Arid Fluvial Sys. Cutbank, Arid Fluvial Sys. AZAZ

Cutbank, Arid Fluvial Sys. Cutbank, Arid Fluvial Sys. AZAZ

Cutbank, Carboniferous Channel Sand, KYCutbank, Carboniferous Channel Sand, KY

Collapsed & Rotated BlockOf Sandstone that fell

Into the Channel

Cutbank, Sand on Sand, Cutbank, Sand on Sand, Jurassic AZJurassic AZ

Box Canyon Cut into Basal Triassic Box Canyon Cut into Basal Triassic Unconformity AZUnconformity AZ

Box Canyon Cut into Basal Triassic Box Canyon Cut into Basal Triassic Unconformity AZUnconformity AZ

Caliche Paleosol, Triassic Redbeds, SpainCaliche Paleosol, Triassic Redbeds, Spain

Caliche Paleosol, Triassic Redbeds, SpainCaliche Paleosol, Triassic Redbeds, Spain

Interbedded Floodplain Siltstones & Musdtones Interbedded Floodplain Siltstones & Musdtones w/Channelw/Channel

Thin Floodplain Muds over Sheet Sand, Devonian, Thin Floodplain Muds over Sheet Sand, Devonian, Arctic CanadaArctic Canada

UpwardsFining

Modern Ergs: Eolian DesertsModern Ergs: Eolian DesertsTropic of Cancer & Capricorn ~25°N & S Tropic of Cancer & Capricorn ~25°N & S (Why Here?)(Why Here?)

Continental Interiors & Rainshadows Continental Interiors & Rainshadows (Find 2)(Find 2)

Facies Model for an Erg Facies Model for an Erg (Desert)(Desert)

Cyclic Stratigraphy of DunesCyclic Stratigraphy of Dunes

Climate, Sea Level, WT Change

MBS: Deflation, Lags, Ventifacts, Desert Varnish, Blow Outs, Downlap

Stream (WT) Cutting Dunes, Stream (WT) Cutting Dunes, ColoradoColorado

Interdune Pond: Mudcracks Interdune Pond: Mudcracks w/Silt, Gobiw/Silt, Gobi

Slumped Bed on Face of Dune, Navajo Sandstone, ArizonaSlumped Bed on Face of Dune, Navajo Sandstone, Arizona

The Barchan Dune that ate the Truck, GobiThe Barchan Dune that ate the Truck, Gobi

Deflation Surface Ventifacts w/Desert Varnish GobiDeflation Surface Ventifacts w/Desert Varnish Gobi

Deflation Surface Comet Marks: Sand in Lee, GobiDeflation Surface Comet Marks: Sand in Lee, Gobi

The Ventifact: Wind Faceted The Ventifact: Wind Faceted StoneStone

Deflation Surface w/Ventifacts, Triassic SpainDeflation Surface w/Ventifacts, Triassic Spain

Deflation Surface w/Ventifacts, Permian ScotlandDeflation Surface w/Ventifacts, Permian Scotland

Lacustrine DepositsLacustrine Deposits

Lacustrine Oil Shales Green River Fm, Eocene WYLacustrine Oil Shales Green River Fm, Eocene WY

Varved Glacio-lacustrine Clay/Silt, Pleistocene, ONVarved Glacio-lacustrine Clay/Silt, Pleistocene, ON

Dropstone(see notes)

Hypothetical Coastal Depositional System FaciesHypothetical Coastal Depositional System Facies

South Carolina Barrier Islands Spit Bars, Tide FlatsSouth Carolina Barrier Islands Spit Bars, Tide Flats

South Carolina Barrier Islands EstuarySouth Carolina Barrier Islands Estuary

Galveston Island & Matagordia Bay, TexasGalveston Island & Matagordia Bay, Texas

What are the green curves?

What is this feature?

Dune & Beach, South Padre Island (Galveston, Texas)Dune & Beach, South Padre Island (Galveston, Texas)

Turbulent Dispersion of Turbulent Dispersion of Shelf MudsShelf Muds

after Hurricane Ida MODIS after Hurricane Ida MODIS 10/10/0910/10/09

Sh

elf

Ida’

sP

ath

See Notes

The End of Part 1!The End of Part 1!