TA2910 01 - Introduction to Sedimentology

8/10/2019 TA2910 01 - Introduction to Sedimentology

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Challenge the future

DelftUniversity ofTechnology

M.E. Donselaar

Sedimentology lectures

TA2910


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Sedimentology lectures

Duration: 14 hours

Examination BSc: written

Date and location:

Thursday 2 February 2012, 14:00-17:00 h Room (?)


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Book

A textbook is used as additional, compulsory information tothe lectures

Title: Sedimentology and StratigraphySecond EditionAuthor: Gary Nichols

ISBN: 978-1-4051-3592-4

Publisher: Wiley-Blackwell


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Sedimentology exam

Book Sedimentology and Stratigraphy

PowerPoint files

Your lecture notes

N.B.: tentamencijfer voor dit vak staat los van cijfer voorpracticum Sedimentologie I (TA2911)


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Access to PowerPoint files

Log in on: http://blackboard.tudelft.nl

Enroll

Course name TA2910 Sedimentologie (2011-2012 Q2)
http://blackboard.tudelft.nl/http://blackboard.tudelft.nl/


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Lecture contents

General part:

- Sedimentology in education & research TA

- Definitions and concepts

- Analysis methods

Sedimentary environments:

- Fluvial, aeolian, lacustrine, coasts, shelf, deep

marine sands


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Sedimentology inthe teaching program

TA3820 Petroleum Geology

TA3942 Geology fieldwork Vesc

AES1800 Exploration GeologyAES1810 Production Geology

AES1820 Reservoir Development

AES1902 Reservoir geology Fieldwork Huesca

AES2006 Graduation thesis


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Definitions and concepts

What is sedimentology?

Sedimentary environment

Sedimentary facies

Sequences Cyclicity

Facies analysis


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Sedimentary facies

Sequences Cyclicity

Facies analysis


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Sedimentology: Definition

Part of the Geology concerned with the study of sedimentsand sedimentary rocks

Physical processes of transport and sedimentation

Composition of the sediments

Analysis of the diagenetic processes

Construction of predictive models


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Sedimentation synergy of:

Sediment supply

Changes caused by chemical, biological and physicalprocesses

Accommodation space


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Accommodation space

The space in a sedimentary basin

where sediment accumulation can take place


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Accommodation space - 1

Posamentier et al.(1988)


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Accommodation space - 2

Posamentier et al.(1988)


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Sedimentary facies

Sequences Cyclicity

Facies analysis


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Erosional

Non-depositional

Depositional

sed. envir.input output


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Sedimentary environments

Continental: fluvial (braided, meandering)

lacustrine

aeolian

Coastal: deltaslinear (clastic, carbonate)

Marine: shelf

deep marine sands

pelagic


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Sub-environments:Example barrier island


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Sedimentary facies

Sequences Cyclicity

Facies analysis


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Sedimentary facies

Each sedimentary environment has its own set of sedimentarycharacteristics.

In combination, the set of facies characteristics defines thesedimentary environment

Geometry

Lithology

Sedimentary structures

Palaeo-flow patterns Fossil contents


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Sedimentary facies

Sequences Cyclicity

Facies analysis


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Sequence

Vertical succession of sedimentary facies


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Sequence - example

Bioturbated mudstone with marine

trace fossil assemblage

Thin, very fine-grained, parallel

laminated sandstone beds alternatingwith bioturbated mudstone

Thick, non-bioturbated medium-grained, cross-bedded sandstone

beds

15 m


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Sequences:Walthers Law of Facies (1894)

Facies occurring in vertical contact with each other must be

the product of spatially neighbouring environments and

that facies occurring in a sequence conformably above one

another were formed in laterally adjacent environments

W lth L 1 S ti ll


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Walthers Law 1: Spatiallyneighbouring environments


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Walthers Law 2: Change in geologicaltime

Sea level fall: Coastline

expands seaward

W lth L 3 R lti f i


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Walthers Law 3: Resulting faciessuccession

barrier beach complex

shoreface


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Sedimentary facies

Sequences Cyclicity

Facies analysis


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Cyclic sequence: definition

A repeating vertical succession of sedimentary facies


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Cyclic sequence: Example

Active

Channel

sequence

Active

Channel

sequence

Active

Channel

sequence

Cycle 1

Cycle 2

Cycle 3

Cycle 4


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Cyclicity

Auto-cyclicity:

Rhythmic repetition of facies caused by a repetition ofsedimentary processes within the depositional environment(e.g., position switching of delta or river)

Allo-cyclicity:

Rhythmic repetition of facies caused by external factors(e.g., tectonics, climate)


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Sedimentary facies

Sequences Cyclicity

Facies analysis


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Facies analysis

Observation Interpretation Prediction

Observation: facies analysis

Interpretation: reconstruction of depositionalenvironment

Prediction: spatial distribution


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Methods of facies analysis

Geometry

Lithology


Palaeo-current distribution Fossils

Cores

Wireline logs


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Geometry

Topography during deposition

Post-depositional development

N.B.: geometry alone does not define the depositionalenvironment


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Geometry

Selley (1985)

lens lens

shoestring wedge

fan wedge

sheet


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Geometry

Lithology



Cores

Wireline logs


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Lithology

Composition of the sediment

Limestone:

Lithology linked to depositional environmentClassification based on fossil contents

Sandstone:

Lithology reflection of transport processes

Analysis of grain size, sequences, mineralogy


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Geometry

Lithology



Cores

Wireline logs


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Most sedimentary deposits are the result of transport ofsediment particles

Transport of particles by gravity, flow of water, wind, ice, ordense mixtures of sediment and water

Interaction of sediment particles with transporting mediaresults in formation of bedforms

Bedforms may be preserved as sedimentary structures


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Pre-depositional:

Structures form by erosional processes in earlystages of deposition

Examples: channel erosion, sole marks

Syn-depositional:

Formed during deposition : indicative of energy

Example: ripples

Post-depositional:

Deformation after deposition

Pre-depositional structures: Channel


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Pre depositional structures: Channelerosion

3.5 m22 m


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Channel erosion

Size and shape of the erosion are measure for river size andflow energy

Flow direction can be measured from orientation of theerosional scour


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Pre-depositional structures: Sole marks

Sole marks form when theupper part of a clay bed isscoured by a water currentor object, and the scour is

subsequently filled with sand When filled, the original

depression forms a ridgebelow the sand bed surface(= cast, afgietselin Dutch)


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Types of sole marks

Groove marks

Flute marks

Bounce marks

More on this: http://course1.winona.edu/csumma/FieldTrips/Sedimentary

Structures/sole_marks/Default.htm
http://course1.winona.edu/csumma/FieldTrips/SedimentaryStructures/sole_marks/Default.htmhttp://course1.winona.edu/csumma/FieldTrips/SedimentaryStructures/sole_marks/Default.htmhttp://course1.winona.edu/csumma/FieldTrips/SedimentaryStructures/sole_marks/Default.htmhttp://course1.winona.edu/csumma/FieldTrips/SedimentaryStructures/sole_marks/Default.htm


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Flute marks

Eddies formed by turbulent flow scour in muddy surface

Irregular depressions with a "pointy upstream end, and amore gentle, flared downstream end that merges into the bedsurface

Crescent marks: crescent-shaped depression by flow aroundan object resting on the muddy surface

Shape is used to determine palaeoflow direction


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Flute marksCross-section

Top view

flow

Reineck & Singh (1975)


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Crescent marks

flow

Horizontal flow eddy around object


Downstream: vortexcauses flow

deceleration anddeposition

Upstream end ofobstacle: flow excavates

semi-circular depression


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Crescent marks

Downstream: vortexcauses flow

deceleration anddeposition

Upstream end ofobstacle: flow excavatessemi-circular depression

flow


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Bounce marks

Forms when a tool bounces across a muddy substrate andcreates a small depression that is later filled with coarsersediment

Gives indication of palaeoflow orientation



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Types of sole marks

Crescent marks

Flute marks Groove marks


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Syn-depositional structures

Structures formed by moving sediment

Wind, water are transporting agents

Sediment transported in suspension or along surface

Surface transport depends on:

Grain size

Flow strength

Transported as:

No bed forms

Ripples (height up to 4 cm)

Dunes (height > 4 cm)


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Sedimentary structures: Planar cross


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bedding

Bed forms and sed. structures:


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Sinuous-crested ripples


Sinuous crested ripple

Trough cross-bedding

Bed forms and sed. structures:


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Isolated linguoid ripples


Linguoid ripples

Trough cross-bedding


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Sedimentary structures: trough cross


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bedding

Sedimentary structures: trough cross


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bedding


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Post-depositional structure: waterb k l


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escape breaks up layer

M h d f f i l i


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Geometry

Lithology


Palaeo-current distribution

Fossils

Cores

Wireline logs


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P l t di t ib ti 2


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Palaeo-current distribution - 2

foreset laminae

brink point

Dip direction =palaeo-current


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M th d f f i l i


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Geometry

Lithology


Palaeo-current distribution

Fossils

Cores

Wireline logs

F il t t 1


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Fossil contents - 1

Is fossil in-situor transported?

Was living environment of the fossil same as that of recentdescendants? (Do actualisticprinciples apply?)

F il t t 2


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Fossil contents - 2

(Micro) body fossils: skeletons, shells or plant remains

Trace fossils: imprints of plants or animals (e.g., burrows,crawling traces)

Bod fossils


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Body fossils

Corals

Spirifer-shells


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Trace fossils 1


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Trace fossils - 1

Helminthoides

Trace fossils 2


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Trace fossils - 2

Scolicia


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Geometry

Lithology


palaeo-current distribution

Fossils

Cores

Wireline logs

Core analysis


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Core analysis

Limitations: core is narrow (10 cm diameter)

Geometry: correlation?

Vertical grain size sequences


Fossil contents

Core: example


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Core: example

Njord Field, Haltenbanken area

Tilje Fm (M. Jura)

Inshore tidal deposits

Rhythmic alternation of thin

sandstone (light colours) andclaystone (dark) layers



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Geometry

Lithology


palaeo-current distribution

Fossils

Cores

Wireline logs

Wireline logs


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Wireline logs

Interpretation lithology/structures from wireline logs

- Gamma-ray log

- Sonic log

- Dipmeter log

- Formation Micro-Imager (FMI) log

Gamma-ray logs - 1


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Gamma-ray logs - 1

Natural radio-activity in U,Th, K

High in clay, low in sand

Beware!:

Mica

Glauconite

Zircon

low readings if caved-in


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Gamma-ray logs2


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y g

Base of sand interval: sharp

decrease in gamma-ray readings:

sand on top of clay

Top of sand interval: gradualfining-upward grain-size

succession produces gradually

increasing gamma-ray readings

Selley (1985)

Gamma-ray logs3


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y g

Base of sand interval withclaystone pebbles produces

gradual decrease of gamma-ray

readings

Top of sand interval: gradual

fining-upward grain-size

succession produces gradually

increasing gamma-ray readingsSelley (1985)

Gamma-ray logs - 4


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Gamma ray logs 4

FMS and FMI tools


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FMS and FMI tools

Formation Micro-Scanner (FMS)

and Micro-Imager (FMI) tool

High resolution (5 mm) resistivity

measurement of borehole wall

Used for visualization and

interpretation of fractures and

sedimentary structures

Borehole Image log: principle


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Borehole Image log: principle

Schlumberger Well Service (1992)


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FMI log:

Sine-wave is roll-out

of an inclined plane

cut by a cylinder

Example of FMI log interpretation


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Example of FMI log interpretation

Compulsory reading


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Compulsory reading

Chapter 4 Processes of Transport and SedimentaryStructures

Chapter 11.7 Trace fossils

TA2910 01 - Introduction to Sedimentology

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