Lecture Outline Friday March 2 thru Wednesday March 7, 2018 Questions? Lecture Exam Friday March 9, 2018 Same time, Same room Bring Pencils and WSU ID 50 question Multiple Choice, Computer Graded Interlude B,E; Chapters 6,7,10,9 Study Guide and review slides are on-line http://www.wsu.edu/~geology101/sec1 Exam 2 study session in Webster 16 Monday March 5 from 6:00-7:30pm - Afshin Khan Monday March 5 from 7:30-9:00pm - Kurt Wilkie Key Points for today What are the different types of stress and strain and how do you recognize them. How can you determine the fault type from one another? - Which side is the hanging wall? - Which side is the footwall? What does the strike and dip of a rock tell us? Chapter 9 Crags, Cracks, and Crumples: Crustal Deformation and Mountain Building Structural Geology - The branch of geology devoted to crustal deformation and the creation of non-volcanic mountains. Understand the difference between map view and cross-section view (profile view). Rocks under Stress are deformed or Strained. force acting on the rock the resulting change in shape or volume Types of Stress - Where rocks are compressed or pushed together. Boundaries - Where rocks are, away from one another. Boundaries, zones of Continental Rifting - Rocks shift past one another in a horizontal motion. Boundaries Strain When a rock is stressed it may become deformed, changing in shape and/or volume = strain. Types of Strain (Deformation) deformation strain, goes back to original form when stress is released. failure Permanent strain, (faults). deformation Permanent strain, (folds).
Faults Brittle failure results in cracks or fractures in rocks. If has taken place along the fracture, it is called a. If movement has taken place along the fracture it is called a. The fault plane is the surface along which movement takes place. Types of Faults faults Side to Side (Horizontal) Motion. Result of. Left-lateral Right-lateral Dip-Slip Motion is along the fault plane; caused by compression or tension. - - The easiest way to determine the type of vertical motion is to see a cross-section (side view). Based on relative motion. Draw a stick figure across the fault plane! Normal. = Tension Reverse. = Compression How to determine fault type Is the motion vertical or horizontal? Can the motion be seen in a cross-section or map view? If horizontal (map view) - right or left motion? Right-Lateral Strike Slip Fault Left-Lateral Strike Slip Fault If vertical (cross-section view) - HW has moved up or down relative to FW? Normal (HW relative to FW) Reverse (HW relative to FW) Faults, Stress and Strain All faults are an expression of, but each result from different types of stress. Fault: Stress: Plate Tectonic: Convergent Divergent & Rifting Transform Other fault types: Thrust - Continental Rifting normal faulting combining strike slip and normal fault motion
Key Points for today What are the different types of folds and how do you tell them apart? How do oil and gas deposits form? Where and why does oil and gas accumulate in certain area? Are there any alternatives to a hydrocarbon based energy sources? --------------------------------------------------------------------------------------------------------------------------------- Review: Name the 3 types of stress: What type of strain (deformation) do we see in rock? What is the difference between a faults and joints? ------------------------------------------------------------------------------------------------------------------------------- Geologic information is recorded on maps and includes rock types, the orientation of the rock units, folding and faulting information. All this information is used to create cross-sectional (profile) views. Strike & Dip: A way to measure rock orientation Direction of the intersection of a rock layer with horizontal surface. Dip 45 Strike and Dip Symbol FOLDS - Folds result from compression Most folding occurs at depths where the temperature and pressure are much higher and the rocks can bend without fracturing. Folds Folds form when. They are a structural feature, different than a hill or valley (which may form only from erosion). Generally, folds form when rocks undergo (type of strain) from (type of stress). At what type of plate boundaries would you expect them to be associated with?
Types of Folds Syncline (like a U ). Youngest rocks found at the of the fold (near axis) Anticlines (like an A ) Oldest rocks found at the. Parts of a fold (in your own words describe) Fold axis imaginary line that divides a fold along its surface Axial Plane a imaginary plane that divides the fold symmetrically as possible Limb half of the fold Fold Axis Horizontal Fold Axis Plunging Fold Axis axis dips into the Earth Horizontal axis Plunging axis Fold shape Symmetrical folds - beds have about the same dip in each limb Asymmetrical folds - beds in one limb dip more steeply than the other Overturned fold - have limbs that dip in the same direction What do folds look like on the surface (map view)? Syncline: Horizontal Fold Axis - Series! Fold Axis: Beds are not parallel they. Look like folds on top view too. Zig-zag shape.
Special types of Folds is a special type of anticline. is a special type of syncline. There is no fold axis, beds dip from a central point. Look like concentric circles on MAP view. Note - by analogy, a dome is shaped like an upside down bowl, and a basin like a bowl Key Points for today Where are folds and faults found in the US? Review of Folds: A geologic tour of the US The next portion of the lecture will pull together some information on the geological make-up of America. I will cross the U.S. by highlighting a series of topographic and tectonic regions. For each region addressed, note what the tectonic setting is, the stress conditions, what rocks and structures are found there. The regions include: Appalachian Mountains: Tectonic setting: Stress conditions: Rocky Mountains: Tectonic setting: Stress conditions: Basin and Range: Tectonic setting: Stress conditions: Colorado Plateau:
Energy Resources Oil and Natural Gas Forms from the accumulation of (shells of organisms) on the sea floor. Sedimentation rate is high (buries organics). so organic matter does not decompose. Buried sediments undergo chemical reactions from increased temperatures and pressures. (max. 130 ºC) Organics converted to liquid and gaseous compounds of (hydrocarbons). of oil and gas allow them to migrate through permeable rocks. Oil and gas can be trapped under certain geological conditions. Low permeability rocks prevent oil from escaping at the earth s surface. Oil and Gas Traps trap trap What are some alternative energy sources? (see how many you can think of, there are at least 6)