1 / 27

Structure and Sedimentary Rocks (Lab #2)

Structure and Sedimentary Rocks (Lab #2). Fold geometry. See page 238–240 (254–256 5 th Ed.). Faults. What ’ s the footwall? What ’ s the hanging wall? Different types of faults See pages 242–243 (260, 5 th Ed.). The Compass, drawing strike and dip symbols, and the Right Hand Rule.

mindy
Download Presentation

Structure and Sedimentary Rocks (Lab #2)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Structure and Sedimentary Rocks (Lab #2)

  2. Fold geometry • See page 238–240 (254–256 5th Ed.)

  3. Faults • What’s the footwall? • What’s the hanging wall? • Different types of faults • See pages 242–243 (260, 5th Ed.)

  4. The Compass, drawing strike and dip symbols, and the Right Hand Rule

  5. The compass N 360 degrees = = 000 degrees E W = 090 degrees 270 degrees = S = 180 degrees

  6. 000 or 360 N 090 E W 270 S 180 The compass

  7. Drawing a strike and dip symbol What is the orientation determined? 115/37 NE

  8. Drawing a strike and dip symbol 115/37 NE 115 37 NE What is the strike? Done! Remember that if it is a cleavage measurement, the symbol is like this… What is the dip? What is the dip direction?

  9. The Right Hand Rule • The Right Hand Rule is a convention that is used so that strike and dip is always written so that the dip is to the right of the strike direction. • This allows us to show strike and dip without dip direction (particularly important for computer applications). • Examples…

  10. 000 right right 180 Right Hand Rule For example, 000/49 has a strike of 000and a dip of 49 to the RIGHT of 000 (i.e. 090, or East) like this… 49 But 180/49, though it has the same strike, has a dip of 49 to the RIGHT of 180 (i.e., 270 or West) like this…

  11. Right Hand Rule…more examples 090/37 is this… 37 37 but 270/37 is this… 045/63 is this… 63 63 but 225/63 is this…

  12. Right Hand Rule…last comment As a precaution most people continue to indicate direction of dip even when they adhere to the Right Hand Rule. 225/43 NW 045/63 SE 130/27 SW 265/12 N 315/29 SW 010/82 E Which of these isn’t correct (i.e., doesn’t follow the Right Hand Rule)?

  13. Maps and block diagrams • Map (a) on p. 4 shows geological contacts that dip away from a central point at a consistent angle. • Map (b) shows 3 geological units that dip slightly to the east. The outcrop pattern is the result of topography.

  14. Maps and block diagrams • Block diagram (c) shows a folded sequence (younger beds in the middle) but with all units dipping in the same direction. • Block diagram (d) shows a plunging fold. This diagram is made harder by not showing the junction between the units on all the faces.

  15. Sedimentary rocks Supplementary information on sedimentary rocks available in Monroe & Wicander pp. 161–165 (150–156, 5th Ed.)

  16. Sedimentary Rocks & Structure • Clastic — rocks made up of fragments deposited by a flowing medium (air, water, ice) • Non-clastic — rocks made from chemically or biologically derived material

  17. Clastic rocks Clastic rocks are classified according to the nature of the following components: • Grains • Matrix • Cement • Pores

  18. Pores • 10% pore space is not unheard of • Doesn’t sound like much but… • 10 km x 10 km x 10 m = 1 x 109 m3 • at 10% porosity  1 x 108 m3 of pore space (oil?) • = 1 x 1011 litres • = 2.64 x 1010 US gals • = 6.29 x 108 barrels • worth $5.9277 x 1010 (at $91/barrel on January 15) • That’s $59,277,000,000 ($59+ billion)!

  19. Non clastic rocks Non-clastic rocks classified by composition • Carbonate • Evaporite • Biochemical • Chemical

  20. Texture • Refers to the nature and inter-relationship of the constituent particles • most non-clastic rocks are “crystalline” • texture of clastic rocks described by various features

  21. Clastic rock texture • Grain size • Roundness • Sphericity (equidimensionality) • Sorting • size • composition

  22. Sedimentary structures • Primary (physical) • bedding • ripples • cross laminations • graded bedding • cracks • raindrop imprints • etc.

  23. Sedimentary structures • Primary (organic) • Tracks & trails • Burrows • Bioturbation • Stromatolites (moderate scale) • Reefs (large)

  24. Sedimentary structures • Secondary (physical) • Load • Dewatering (fissility, cone-in-cone) • Secondary (chemical) • Nodules & concretions • Dendrites

  25. Other sedimentary features • Colour — can be loosely indicative of the environment of deposition. • Red (hematite) indicates subaerial deposition • Black (carbon) indicates reducing environment • Maturity — chemical stability and degree of sorting of components indicating distance of transportation from source area.

  26. Last exercise • Apply the revised sedimentary rocks information to a suite of 5 rocks found in the 6 drawers at the back of the lab labeled rock and fossil samples (not those in the benches)

  27. Questions?

More Related