glg310 structural geology - arizona state...

GLG310 Structural Geology

Announcements

• Reminder: Application exercise on

Tuesday, Sept. 17 in class

• How do videos look and work?

• Homework questions?

12 September 2013 GLG310 Structural Geology

Strain and deformation

• Stretch (strain) ellipse

• Rotation of lines in deformation

• Pure and simple shear

• Progressive deformation

• Deformation by change of volume



Moving from 1 to 2 to 3

dimensional deformation • E and s as we have

defined them in the last two lectures are 1 dimensional (measured along lf).

• In a deformed material; however, we can define the minimum and maximum stretches and they will be perpendicular

Smin=lfmin/l0

Smax=lfmax/l0

l0

l0

lfmax

lfmin


Principal stretches

Sphere Ellipsoid

In 3D, S1 is max,

S3 is min, and S2 is

intermediate

Cube Prism


Deformed

trilobites

do exist!

Draw the

stretch

ellipse for

each

Angular shear

“Coaxial deformation”:

Lines parallel to principle

axes do not rotate

“Pure Shear”

12 September 2013

“Non-Coaxial deformation”:

Principle axes are constant

but lines rotate with

progressive deformation

“Simple Shear”

Progressive deformation

Cloos’ strain study


Measured stretch ratios in rocks from

around the world

“Flattening”

More common

“C

on

stri

ctio

n”

-Suppe, 1985

Deformation by loss of

material

-dissolution

-”styolites”

http://www.earth.lsa.umich.edu/~vd

pluijm/animations/stylolite.mov

http://www.geol.umd.edu/~jmerck/geol100/images/15/stylolite.jpg

http://www.earth.lsa.umich.edu/~vdpluijm/animations/stylolite.mov

http://www.earth.lsa.umich.edu/~vdpluijm/animations/stylolite.mov


Stylolite: Wave-like or tooth-like, serrated, interlocking surfaces most

commonly seen in carbonate and quartz-rich rocks that contain

concentrated insoluble residue such as clay minerals and iron oxides.

Stylolites are thought to form by pressure solution, a dissolution

process that reduces pore space under pressure during diagenesis.

Schlumberger Oilfield Glossary

http://www.glossary.oilfield.slb.com/Display.cfm?Term=stylolite




http://www.asaa.com.au/publicati

ons/magazines/DS16_DrDripston

eStylolites.pdf

http://www.asaa.com.au/publications/magazines/DS16_DrDripstoneStylolites.pdf




Pro

gre

ssiv

e s

train

His

tory o

f re

gio

nal

def

orm

ati

on

in

sou

ther

n A

rizo

na

Stretching and

Shortening

working together

in partnership

-Pollard and Fletcher,

Fundamentals of Structural

Geology, 2005

glg310 structural geology - arizona state...

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