Pa Leo Current Analysis PDF

8/2/2019 Pa Leo Current Analysis PDF

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Paleocurrent Analysis

By: Jason Choquette


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OverviewWhy is paleocurrent analysis important?

Fabric and why its useful

Internal and external structures

How they are related to each other

Liner structures; types and uses

Practial study of paleocurrents in westernMaine and some implications


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DefinitionPaleocurrent- The study of ancient flow

Paleocurrent indicators- oriented

sedimentary structures interpreted to have

been deposited by ancient flows


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Paleocurrent Indicators IncludeCross-beds

clast imbrication/fabric

tool marks

groove casts and molds

ripple crest orientation


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Paleocurrent Analysis.Provides direct information about the orientation

of the sedimentary systems.Yields information about the flow directions ofrivers, longshore currents, sediment gravity flows,

and paleowindsProvides direction of initial dip or paleoslope

Yields clues to the provenance of sediment supply

Aids in determining geologic setting to which itwas placed

Provides info on paleogeography


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Three Maine flow IndicatorsFabric

External structures

Internal structures


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FabricsRefers to the spatial orientation of material

in which they where deposited.Includes various material types ranging in size

from large cobbles to micro-fabricsFossils

Encompasses other fields lithologies such as

carbonate rocks and volcanic deposits

Imbricated bedding


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Uses of fabric analysis

Largely used to infer current directions in

sand and gravels.

Reconstruct glacial motion

Primarily used if there is no other flow

indicators or to support other data.


9/34www2.umt.edu/.../hendrix/g432/g432_L12.htm
http://www2.umt.edu/GEOLOGY/faculty/hendrix/g432/g432_L12.htmhttp://www2.umt.edu/GEOLOGY/faculty/hendrix/g432/g432_L12.htm


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Compton Robert R. Geology in the Field, 1985 p.52
http://www2.umt.edu/GEOLOGY/faculty/hendrix/g432/g432_L12.htm


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Internal and External Structurese.g cross bedding and ripple marks

Used in unison to map large areas

Both are found in many geologic

environmentsFluvial

Littoral

Marine

Aeolian
http://www2.umt.edu/GEOLOGY/faculty/hendrix/g432/g432_L12.htmhttp://www2.umt.edu/GEOLOGY/faculty/hendrix/g432/g432_L12.htmhttp://www2.umt.edu/GEOLOGY/faculty/hendrix/g432/g432_L12.htmhttp://www2.umt.edu/GEOLOGY/faculty/hendrix/g432/g432_L12.htmhttp://www2.umt.edu/GEOLOGY/faculty/hendrix/g432/g432_L12.htmhttp://www2.umt.edu/GEOLOGY/faculty/hendrix/g432/g432_L12.htmhttp://www2.umt.edu/GEOLOGY/faculty/hendrix/g432/g432_L12.htmhttp://www2.umt.edu/GEOLOGY/faculty/hendrix/g432/g432_L12.htmhttp://www2.umt.edu/GEOLOGY/faculty/hendrix/g432/g432_L12.htm


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Some Internal Structures


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www2.umt.edu/.../hendrix/g432/g432_L12.htm


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Some External Structures


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www2.umt.edu/.../hendrix/g432/g432_L12.htm


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http://www.ualberta.ca/~jwaldron/images/sedCD1024/05.jpg


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http://www.depauw.edu/acad/geosciences/tcope/SedStruct/HiRes/LinguloidRipples.jpg


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http://www.coloradocollege.edu/dept/GY/pmyrow/Web%20Photos/Solemarks2.jpg


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https://reader009.{domain}/reader009/html5/0504/5aeb441227c9c/5aeb4


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http://www.studiozoic.com/adventures/2004/pct/wa/IMG_4153.jpg


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Paleocurrent Analysis in PracticeCombining internal and external structures

to develop a

Detailed map

Paleoslope

Tectonic history
http://www2.umt.edu/GEOLOGY/faculty/hendrix/g432/g432_L12.htmhttp://www2.umt.edu/GEOLOGY/faculty/hendrix/g432/g432_L12.htmhttp://www2.umt.edu/GEOLOGY/faculty/hendrix/g432/g432_L12.htmhttp://www2.umt.edu/GEOLOGY/faculty/hendrix/g432/g432_L12.htmhttp://www2.umt.edu/GEOLOGY/faculty/hendrix/g432/g432_L12.htmhttp://www2.umt.edu/GEOLOGY/faculty/hendrix/g432/g432_L12.htm


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Potter, 1977


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Bradley;Hanson, 2002 p.442


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ReferencesLunguloid ripples jpeg from;

http://www.depauw.edu/acad/geosciences/tcope/SedStruct/HiRes/LinguloidRi

pples.jpgRipple marks

http://www.studiozoic.com/adventures/2004/pct/wa/IMG_4153.jpg

Bradley Dwight C., Hanson Lindley S., Paleocurrent analysis of a deformed

Devonian foreland basin in the Northern Appalachians, Maine, USA.Sedimentary Geology, 148 (2002) p.425- 447

Potter Paul E., Pettijohn Francis J., Paleocurrents and Basin Analysis, second

edition. Springer-Verlag, Berlin Hiedelberg New York, 1977

Lewis D.W. Practical Sedimentology, University of Canterbury NZ. 1984.

Compton Robert R., Geology in the Field. 1985 p. 52, 162-175

Class handout thingy
http://www2.umt.edu/GEOLOGY/faculty/hendrix/g432/g432_L12.htmhttp://www2.umt.edu/GEOLOGY/faculty/hendrix/g432/g432_L12.htmhttp://www.depauw.edu/acad/geosciences/tcope/SedStruct/HiRes/LinguloidRipples.jpghttp://www.depauw.edu/acad/geosciences/tcope/SedStruct/HiRes/LinguloidRipples.jpghttp://www.studiozoic.com/adventures/2004/pct/wa/IMG_4153.jpghttp://www.studiozoic.com/adventures/2004/pct/wa/IMG_4153.jpghttp://www.depauw.edu/acad/geosciences/tcope/SedStruct/HiRes/LinguloidRipples.jpghttp://www.depauw.edu/acad/geosciences/tcope/SedStruct/HiRes/LinguloidRipples.jpg

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