Ch 4: Sedimentary Structures

TYPES OF BEDDING

bounding surfaces

discontinuous bedding

planar bedding

bedding

graded-bedding

normal graded bedding(fining up)

reverse graded bedding(fining down)

cross-beds

Ripples

ripples

cross-beddingripple video

EOLIAN (WIND) DEPOSITION

Wind

Former position Future position

DepositionErosion

A dune moves forward slowly as sand erodes and is deposited.

eolian cross-bed formation

cross-beds

eolian cross-bedding

eolian

IRREGULAR STRATIGRAPHY

FLAME STRUCTURES

http://www.dept.edu.waseda.ac.jp/earth/top/cover_ph/2004/flame.jpg

BALL AND PILLOW STRUCTURES

DISH AND PILLAR STRUCTURES

http://course1.winona.edu/csumma/images/sedstrx2/dishce.jpg

SOFT SEDIMENT DEFORMATION

http://www.tulane.edu/~eens/geol/fieldtrip2002/Soft_Sediment_Deformation_in_Mono_Lake_beds.jpg

SOFT SEDIMENT DEFORMATION

EROSIONAL STRUCTURES

Erosional Structures

GROOVE CASTS

http://commons.wikimedia.org/wiki/File:Groove_casts.JPG

FLUTE CASTS (CRETACEOUS)

LOAD CASTS

http://course1.winona.edu/csumma/images/sedstrx2/load.jpg

BIOGENIC STRUCTURES

Bioturbation structures

stromatolites

44

MISC STRUCTURES

mud cracks

PARTING LINEATION

http://www4.uwm.edu/course/geosci697/structures/partinglineationpage.html

PALEOCURRENTS

PALEOCURRENTSN (0)

S (180)

W (90)E (270)

N (0)

S (180)

W (90)E (270)

Total  Data  :  43

paleocurrent data e.g.

STRIKE/DIP

similar to Fig. 15.7

imbricated clasts

Unimodal

Unimodal

Bimodal

stratigraphic section

depositional environment

depositional environments

DepositionalenvironmentsDepositional Environments

3. depositional environments