Download INTRODUCTION TO DEFORMATION IN ROCKS

INTRODUCTION TO
DEFORMATION IN ROCKS
Malay Mukul
CSIR Centre for Mathematical
Modelling and Computer Simulation
BANGALORE 560 037
PROCESS-RESPONSE MODEL
RESPONSE MODEL
Empirical Model
(Predictive)
Geometric Model
(Observational)
Statistical Model
(Regression Analysis)
Conceptual Model
(Inferential)
PROCESS MODEL
Computer Simulations
Mathematical Model
Statistical Comparison
(Observations vs Predictions)
DEFORMATIONAL SETTING
DEFORMING SYSTEM
SPECIFICATIONS
Initial Position
Position
Final Position
ONE STATE
CHANGE OF STATE
(TWO STATE)
Initial Position
T1
T3
T0
Initial Position
Final Position
T2
Final Position (T4)
SEQUENCE OF STATES
DATED PATH (FULL HISTORY)
DEFORMATION HISTORY
•
GPS Maximum: 9 years (1993-2002)
GTS & Seismology (1800s – 2002)
Geophysical data
•
Paleoseismology (100s to 1000s years)
Sediments
Neotectonics: 1, 000-150, 000 years
Sediments in uplifted terraces
•
•
Geology: 150, 000 years to Billions of years
Rocks
QUATERNARY DEFORMATION
T3
T2
T1
QUATERNARY DEFORMATION
T4
T3
SCALES OF DEFORMATION
•
PLATE SCALE: Typically 1000s of km
Plate Motions and Stresses
•
WEDGE SCALE: Typically 100s of km
Critical Wedge Models
•
THRUST SHEET SCALE: Typically 10s of km
Slip and Propagation Rates of Thrust Faults
•
FAULT ZONE DEFORMATION: < 1 km
Frictional and Plastic Microscopic
grain-size reduction mechanisms
PLATE SCALE DEFORMATION
WEDGE SCALE DEFORMATION
•
PLATE SCALE: Typically 1000s of km
Plate Motions and Stresses
•
WEDGE SCALE: Typically 100s of km
Critical Wedge Models
•
THRUST SHEET SCALE: Typically 10s of km
Slip and Propagation Rates of Thrust Faults
•
FAULT ZONE DEFORMATION: < 1 km
Frictional and Plastic Microscopic
grain-size reduction mechanisms
WEDGE SCALE DEFORMATION
Mukul, 2000
SCALES OF DEFORMATION
•
PLATE SCALE: Typically 1000s of km
Plate Motions and Stresses
•
WEDGE SCALE: Typically 100s of km
Critical Wedge Models
•
THRUST SHEET SCALE: Typically 10s of km
Slip and Propagation Rates of Thrust Faults
•
FAULT ZONE DEFORMATION: < 1 km
Frictional and Plastic Microscopic
grain-size reduction mechanisms
SHEET SCALE DEFORMATION
FAULT ZONE SCALE
DEFORMATION
•
PLATE SCALE: Typically 1000s of km
Plate Motions and Stresses
•
WEDGE SCALE: Typically 100s of km
Critical Wedge Models
•
THRUST SHEET SCALE: Typically 10s of km
Slip and Propagation Rates of Thrust Faults
•
FAULT ZONE DEFORMATION: < 1 km
Frictional and Plastic Microscopic
grain-size reduction mechanisms
IMPORTANCE OF SCALE
•
PLATE SCALE: Typically 1000s of km
Can regards the deformed body as a continuum
and look at its response to stress
Can regard the plate to be elastic
•
WEDGE SCALE: Typically 100s of km
Continuum but not completely elastic
•
THRUST SHEET SCALE: Typically 10s of km
Continuum but not completely elastic
•
FAULT ZONE DEFORMATION: < 1 km
Not Continuum, Metallurgical Approach
STUDY OF ROCK DEFORMATION
•
Continuum Mechanics Approach
Deformed Body is regarded to be continuous
Look at response to stress
•
Metallurgical Approach
Deformation studied at atomic scales using
Atomic Scale Flow Laws and Deformation
Mechanisms
•
Effects seen under Petrological Microscope
DEFORMATION IN ROCKS
[STRESS] =
{MATERIAL PROPERTIES}* [STRAIN]
STRESS - Cause of Deformation
STRAIN - Effect
MATERIAL PROPERTIES –
Controlling Factor: Continuum
Grain Scale
Atomic Scale
Scale