Lecture 9 Depositional Environments

8/2/2019 Lecture 9 Depositional Environments

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Primary-syn sedimentation (e.g. bedforms)

econd r - ost sediment tion e

bioturbation)


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Flute casts


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Groove casts


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Eolian deflation surface, Mars (just kidding, its Argentina)


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Mucracks, Salinas Grande, northern Argentina


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Mudcracks in Jurassic strata southern Utah


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Flame structures, Paleocene, Pt. Lobos, CA


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Miocene gas escape structures, Sta. Rosalia, Baja


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Cretaceous marine deposits, dinosaur track or gutter casts? NW


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Biogenic structures: Stromatolites


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-Continental (alluvial, fluvial, eolian,transitional)-Marine


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I. Depositional System= consists of associated sedimentaryenvironments

Facies= a group or related items

Lithofacies= a group or related rocks of a particular

lithology

Facies Model= a general summary of a particular

distribution of facies in many modern and ancientexamples.


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II. Alluvial Fan

characterized by:Radial geometry oca on nex o e moun a n ronGravity flows (debris flows) in the proximal part

Channels gets smaller downstream

The process by which alluvial fan deposit great amount of


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Salt Creek fan, California

uv a rom a n o was aga ns vs. uv a a n r ver


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Side-valley alluvial fan, St. Elias Mtns., Yukon Territory


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, -

SSW. Note dendritic pattern across fan surface. Roadencircling fan provides scale.


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Walther's Law = sedimentary environments foundadjacent to each other at one time will be found in

major unconformities (i.e. time missing) exists


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Lecture 9 Depositional Environments

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