Understanding Geology: Deformation and Metamorphism in Physical Geology - Prof. David McCo, Study notes of Geology

Download Understanding Geology: Deformation and Metamorphism in Physical Geology - Prof. David McCo and more Study notes Geology in PDF only on Docsity! 1 Physical Geology Deformation and Metamorphism Today’’’’s Learning Objectives •• Explain how and why rocks behave differently at shallow and deep levels in the crust. •• Sketch and label the three major types of faults. •• Define the terms, strike-slip fault, normal fault, reverse fault, hanging wall, footwall, foliation, anticline, syncline. •• Describe the conditions under which metamorphism would occur and name four metamorphic rocks. •• Explain how metamorphism differs with plate tectonic setting. 08.01.b How Rocks Respond to Stress Displacement –– rocks moved (faults) Strain –– changes in size, shape (metamorphism) Rotation –– rocks tilted (folds) Small amount of stress: block remains essentially unchanged 08.01.c Consider the structural behavior of rocks at shallow versus deep conditions Temperature and pressure increase with depth At shallow depths (low T,P), most rocks break (brittle deformation) Rocks flow in deep conditions (ductile deformation) 08.01.c Consider how minerals respond at shallow versus deep conditions Deep: minerals may recrystallize, new minerals grow Shallow: minerals show little change in composition Temperature and pressure increase with depth 08.02.c Shallow levels: rocks break Compression ________ Deeper levels: rocks flow Shear Observe three kinds of stress and resulting structures. _________ folds Joints, fractures faults Folds, shear zones stretching 2 08.04.a Describing Faults Strike-slip fault –– movement on fault parallel to strike __________ –– fault movement parallel to dip Strike –– horizontal line on an inclined surface Dip –– inclination or slope of surface (measured from horizontal) Hanging wall –– above fault Footwall –– below fault 08.04.b Reverse fault or thrust fault –– hanging wall moves up (compression) Normal fault –– hanging wall moves down (tension) Fault Movement Which letter is in the hanging wall of the labeled fault? 0% 0% A. A B. B A B fault 10 What type of fault is illustrated in this image? 0% 0% 0% 0% A. Normal fault, hanging wall moved up B. Reverse fault, hanging wall moved up C. Normal fault hanging wall moved down D. Reverse fault, hanging wall moved down 10 0% 0% If this is a normal fault, Professor McConnell is standing on the ___________? A. Hanging wall B. Footwall 10 08.04.c Strike-Slip Faults Rocks move horizontally –– define movement by looking across fault for offset features Left lateral Right lateral