Geology 209(02)-Fall 2001 There will be a brief review of chapters 7-11 at the Lecture 17: November 8 end of this lecture Chapter ll There will be no lecture on Rock Deformation Tuesday, November 13, 2001 (Reading Days) Note: Second Midterm exam Recap of last lecture( Chapter In November 15, 2001@9: 30 AM(60 min) Different types of stress: in ST 140 50 multiple choice questions on Chapters 7-11 tensile shear Bring your student ID and a pencil #2 Different types of response The make-up exam will be on ductile/plastic - folds femur to original shape elastic Tuesday, November 20, 2001 at PM in ES 136 fractures(faults, joints) Location of strata can be described by strike and dip Rock deformation: Fold Types Monoclines A sudden steepening in an otherwise gently dipping Fold Types Fold Axis Axia Limbs dip in rata is called a monocline ymmetrical F. horizontal vertical opposite directi Domes basins Asymmetrical F. horizontal inclined opposite directior Domes and basins are rounded versions of synclines different angles Overturned Fold horizontal inclined same direction Domes: anticlinal cireular structure unbent Fold horizontal horizontal same direction (often older rocks in the middle) Basin: synclinal cireular structure urging Folds inclined (often younger rocks in the middle)
1 Geology 209 (L02) - Fall 2001 Lecture 17: November 8 Chapter 11 Rock Deformation There will be a brief review of chapters 7 ñ 11 at the end of this lecture. There will be no lecture on Tuesday, November 13, 2001 (Reading Days) Note: Second Midterm Exam November 15, 2001 @ 9:30 AM (60 min.) in ST 140 50 multiple choice questions on Chapters 7-11 Bring your student ID and a pencil #2 The make-up exam will be on Tuesday, November 20, 2001 at 2 PM in ES 136. Recap of last lecture (Chapter 11) Different types of stress: ï lithostatic ï compressive ï tensile ï shear Different types of response: elastic rocks return to original shape ductile/plastic folds (synclines, anticlines) brittle fractures (faults, joints) Location of strata can be described by strike and dip. Rock Deformation: Fold Types Symmetrical F. horizontal vertical opposite direction equal angles Asymmetrical F. horizontal inclined opposite direction different angles OverturnedFold horizontal inclined same direction Recumbent Fold horizontal horizontal same direction Plunging Folds inclined Fold Types Fold Axis Axial Limbs dip in Planes Monoclines A sudden steepening in an otherwise gently dipping strata is called a monocline. Domes, Basins Domes and basins are rounded versions of synclines and anticlines. Domes: anticlinal circular structure (often older rocks in the middle) Basin: synclinal circular structure (often younger rocks in the middle)
Rock Deformation Fractures Kinds of faults Direction of DiD angle Normal fault Types Displacement Normal Fault Hanging wall down>45 degree Result of extensio (dip slip fault Reverse Fault Hanging wall u >45 degree (dip slip fault) Thrust Fault Hanging wall up <45 degree Reverse Fault (dip slip fault) Movement on hanging wall is up relative to footwall Strike-slip Fault horizonta 0 degree Result of compression (strike slip fault) Plate Tectonic Settings and Topographic Features Thrust Fault ecial case of reverse fault Strike-Slip Faults or transform faults form long linear val .Fault plane very low angle usually indicated by streams or long lakes Common Fault type in Foothills and Rockies Strike sip Fault Plate Tectonic Settings and Topographic Features Plate Tectonic Settings and Topographic Features Normal Faults Usually in rift zones where the crust stretched. Normal Faults. extension in the crust. rifts Note"Drag of beds along fault. Basin and range topography often caused by heating of deep crustal Fg.11.22 anges are uplifted blocks(horsts)and basins are down thrown blocks (grabens). See Fig. 11.25 Fg.11.26
2 Rock Deformation: Fractures Normal Fault Hanging wall down > 45 degree (dip slip fault) Reverse Fault Hanging wall up > 45 degree (dip slip fault) Thrust Fault Hanging wall up < 45 degree (dip slip fault) Strike-slip Fault horizontal 0 degree (strike slip fault) Fracture Direction of Dip Angle Types Displacement Kinds of Faults Normal Fault ïMovement on hanging wall is down relative to footwall ïResult of extension Reverse Fault ïMovement on hanging wall is up relative to footwall ïResult of compression Strike- slip Fault Thrust Fault ïSpecial case of reverse fault ïFault plane very low angle ïCommon Fault type in Foothills and Rockies Plate Tectonic Settings and Topographic Features Strike-Slip Faults or transform faults form long linear valleys usually indicated by streams or long lakes Stream Bed Offset shows Fault movement Fault trace Fig 3.17 Plate Tectonic Settings and Topographic Features Usually in rift zones where the crust stretched. Note ìDragî of beds along fault. Normal Faults Fig. 11.22 Ranges are uplifted blocks (horsts) and basins are down thrown blocks (grabens). See Fig. 11.25 Plate Tectonic Settings and Topographic Features Basin and range topography often caused by heating of deep crustal rocks. Normal Faults - extension in the crust - rifts Fig. 11.26
Plate Tectonic Settings and Topographic Features Crustal shortenin Chief Mtn. Montana Thrust Faults in regions subject to compressive Precambrian rocks YOU LIVE NEAR ONE OF THE BEST EXPOSED Cretaceous rocks THRUST SEQUENCES ON EARTH! Similar structures CALGARY BANFF ANMORE MORLEY ong Hiway 3 Shortening" in Rockies to west is about 80km Fig.11.28 Fg.1129 Geology 209(L02)-Fall 2001 Lecture 17: November 8 Review. hapters 7-11
3 Plate Tectonic Settings and Topographic Features Thrust Faults in regions subject to compressive stress (colliding plate boundaries) YOU LIVE NEAR ONE OF THE BEST EXPOSED THRUST SEQUENCES ON EARTH! CALGARY MORLEY LAKE LOUISE CANMORE BANFF Fig. 11.28 Crustal Shortening Fig. 11.29 Chief Mtn, Montana Similar structures along Hiway 3 ìShorteningî in Rockies to west is about 80km Precambrian Rocks Cretaceous Rocks Geology 209 (L02) - Fall 2001 Lecture 17: November 8 Review: Chapters 7 - 11
