2. Overview
Why is paleocurrent analysis important?
Fabric and why it’s useful
Internal and external structures
How they are related to each other
Liner structures; types and uses
Practial study of paleocurrents in western
Maine and some implications
3. Definition
Paleocurrent- The study of ancient flow
Paleocurrent indicators- oriented
sedimentary structures interpreted to have
been deposited by ancient flows
5. Paleocurrent Analysis….
Provides direct information about the orientation
of the sedimentary systems.
Yields information about the flow directions of
rivers, longshore currents, sediment gravity flows,
and paleowinds
Provides direction of initial dip or paleoslope
Yields clues to the provenance of sediment supply
Aids in determining geologic setting to which it
was placed
Provides info on paleogeography
6. Three Maine flow Indicators
Fabric
External structures
Internal structures
7. Fabrics
Refers to the spatial orientation of material
in which they where deposited.
Includes various material types ranging in size
from large cobbles to micro-fabrics
Fossils
Encompasses other fields lithologies such as
carbonate rocks and volcanic deposits
Imbricated bedding
8. 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.
12. Internal and External Structures
e.g cross bedding and ripple marks
Used in unison to map large areas
Both are found in many geologic
environments
Fluvial
Littoral
Marine
Aeolian
34. References
Lunguloid ripples jpeg from;
http://www.depauw.edu/acad/geosciences/tcope/SedStruct/HiRes/LinguloidRi
pples.jpg
Ripple 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…