October- 24 2001 The Axial Plane Folds -Layers are bent, but not broken Fig.10.1
1 GLGY 201 Chapter 10 Folds, Faults and Rock Deformation October 24, 2001 October 24, 2001 The Axial Plane Folds - Layers are bent, but not broken Fig. 10.1
Faults- Layers are broken Fault has moved this much These layers were originally together Strike and dip The orientation of structures in the field DIP Go to"courses" page and look at"Strike and Dip Review
2 Faults - Layers are broken These layers were originally together Fault has moved this much Strike and Dip - The orientation of structures in the Field STRIKE DIP Go to ìcoursesî page and look at ìStrike and Dip Reviewî
STRIKE- The direction of the line formed by the intersection of a horizontal plane with a bedding or fault plane Fig. 10 DIP-The angle formed by the intersection of a bedding or fault plane and the horizontal plane. The angle is measured in a vertical plane perpendicular to the strike. The symbol used to display strike and dip on a map is the following 5 Dip angle The strike and dipl symbols on this map can be used to construct this Cross section Fig.10.5
3 STRIKE - The direction of the line formed by the intersection of a horizontal plane with a bedding or fault plane. DIP - The angle formed by the intersection of a bedding or fault plane and the horizontal plane. The angle is measured in a vertical plane perpendicular to the strike. Fig. 10.4 Fig. 10.5 The symbol used to display strike and dip on a map is the following: S 45 trike Dip angle The strike and dip symbols on this map can be used to construct this Cross Section
Chapter 10: Rock Deformation or what you always wanted to know about folds, faults, and joints Stress= the force applied to a plane divided by the area of the plane lithostatic compressive tensile shear forces directed forces directed stress that stress applied toward one away from acts parallel equally another one another to a plane Rock Deformation The change in volume or shape of an object that results from stress(Force/Area)is called strain The response of rocks to stress can be divided into elastic response: rock returns to original shape ductile or plastic response: permanent deformation without fracture occurs above the elastic limit brittle response: fracturing of a rock with little deformation prior to its rupture
4 Chapter 10: Rock Deformation or what you always wanted to know about folds, faults, and joints Stress = the force applied to a plane divided by the area of the plane. stress applied equally lithostatic forces directed toward one another compressive forces directed away from one another tensile stress that acts parallel to a plane shear Rock Deformation The change in volume or shape of an object that results from stress (Force/Area) is called strain. The response of rocks to stress can be divided into - elastic response: rock returns to original shape - ductile or plastic response: permanent deformation without fracture; occurs above the elastic limit - brittle response: fracturing of a rock with little deformation prior to its rupture
STRAIN This bar, length L Is shortened by compressive stress(o,) To length La The strain(change in shape) is Strain (G =(L1-L2 ·100% Deformed at Deformed at Undeformed Shallow Deep Sample Crustal Crustal Conditions Conditions Fig.10.7
5 STRAIN L1 Is shortened by compressive stress (σ1 ): This bar, length L1: L2 σ1 σ1 To length L2 The strain (change in shape) is: Strain (σ1 ) = (L1 ) (L1-L2) ï100% Undeformed Sample Fig. 10.7 Deformed at Shallow Crustal Conditions Deformed at Deep Crustal Conditions