Unformatted text preview: EAS 111 General Announcements 9/15/09
• Schedule Reminder
• Today – Stress, Strain, Geologic Structures • Weds – Folds, Faults, Mountain Building Plan Ahead!
• • • • • • Lecture Exam I review – 9/21/09 – Monday Exam 1 Study guide posted to Blackboard EXTRA OFFICE HOURS 9/21/09 – TUES, 2-4 PM REGULAR OFFICE HOUR 9/22/09 – WED, 1-2 PM Lecture Exam I – 9/22/09 - Wednesday Lab Exam I – Starting 9/21/09 (same week as Lecture exam) EAS 111: Assignments for 9/20/09
• Review/finish assigned reading in Exploring A Family Portrait Earth and Atmospheric Sciences 111
Fall 2010 Rock Deformation II
-Brittle and Ductile deformation reviewed -Folds and Fold Types -Building mountains with folds and faults
-Lecture 7 Sense of Movement
Hanging wall Footwall
08.04.b Normal fault Reverse fault or Reverse thrust fault thrust Strike-Slip Faults
Rocks move Rocks horizontally
08.04.c Left lateral Right lateral Words of the Day - Still
• Stress • Strain • Brittle • Ductile • Fault • Fold Observe three kinds of stress and resulting structures Compression Tension Shear Shallow levels: rocks fracture Deeper levels: rocks flow 08.02.c Consider the structural behavior of rocks at shallow Consider versus deep conditions versus
08.01.c A Which rock of Which these two likely was deformed at higher pressure and temperature, in a ductile fashion? fashion? Temperature and Temperature pressure increase with depth with B Folds Layers can Layers be folded be Anticline Syncline Anticline Syncline 08.05.a Geometry of Folds
g in H e Limb
08.05.b Limb Plunging Plunging fold fold Axial Surface Upright fold Asymmetric fold Overturned fold Hudson-Lander oilfield Western Wyoming This fold is probably… a.a syncline b.a monocline c.an anticline d.a basin If these geologic maps depict rocks on a flat land surface, which of the following can be interpreted as a fold? A B C D OK – so now what?
• Mountains, basins & deformation • Why do we care? • Why are some regions high or low? • What’s the difference between regional and local mountains? • How do folds and faults work together to generate relief? Controls on Regional Elevation Regions with thick Regions crust are high crust Warm rocks Warm are higher than cool ones ones Regions underlain by Regions less dense crust are high less 11.01.a Ways to Increase Regional Elevation Shorten-thicken crust Add surface material Add magma at depth Heat crust or mantle 11.01.d Normal Faults and Tilting of Fault Blocks 08.12.c Above larger normal fault 11.06.c5 11.06.c7 11.12.a1 Fold and Thrust Belts
Thrust faults Folds related to faults Cleavage 08.11.a Convergent Convergent Boundaries Boundaries Fold and thrust belt Shearing and regional Shearing metamorphism metamorphism High T/Low P High P/Low T Mantle Part of Mantle Lithosphere Lithosphere
08.11.b Subducted Subducted Slab Slab Thrust sheets Cleavage and Cleavage shear zones shear Regional metamorphism Regional Regional metamorphism metamorphism Folds Related to Faults
How is it possible for some materials here to break while Reverse Fault others are bending?
08.10.a Reverse Fault A.different pressure and temperature conditions Monocline B.different rock strength properties for different materials C.deformation happened at different times – different stresses D.all of the above potentially Anticline Syncline Think about what might control the elevation of across Think North America North Block faulting Cool, old and stable
Warm mantle, faulting and tilting Fold & Thrust belts continental crust 11.02.m1 Western North Western America America Rocky Rocky Mountains Mountains Great Plains Great to Mississippi to Appalachian Appalachian Mountains Mountains Cool, old and stable continental crust Old, eroded fold and thrust belts ...
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- Spring '10
- Geology, Orogeny, Thrust Belts, Regional Regional metamorphism metamorphism