Homework #7 (Geos 251) due Nov 9 2017 (at start of class) NAME 40 Ma 40 Ma 120 M
ID: 117604 • Letter: H
Question
Homework #7 (Geos 251) due Nov 9 2017 (at start of class) NAME 40 Ma 40 Ma 120 Ma , 27 Ma 40 Ma 9 Ma 25 M3 0 Ma 19 Ma Active 140M 24 Ma *3 Ma 51 to 0 Ma 20 Ma 5 Ma 20 M Show all work, and express your answers in cm/yr (note: km/Ma = 10 x cm/yr) 0 1000 2000 3000 4000 5000 (kilometers) 1. Please use the distance scale and the age of 27 Ma to determine the rate of plate "D" over the hot spot. 2. The sediment at W is a turbidite. What is unusual about the bedding in a turbidite? 3. Us the age of 24 Ma to determine the rate plate C moving away from plate D: 4. When is the age of youngest oceanic crust between plates C and D? 5. Use the age of 20 Ma to determine the rate of plate A moving away from plate B: 6. What is the oldest crust on Plate B? 7. What is the sense of motion along the transform fault at"x"? (right-slip or left-slip) 8. Which plate is bring consumed along the subduction zone shown with the letter"y 9. Plate D contains oceanic crust that is 140 Ma. What would you guess is the oldest ocanic crust on plate D? 10. What type of rock would you expect on top of the active hot spot?Explanation / Answer
1. The plate has moved almost 4.5 cm in the map . it would be almost 2000 Kms. ie 2000 km / 27 Ma = 74.07 km/ Ma. i.e 7.4 cm/yr.
2. A turbidite deposit shows grdaed bedding. This is called a bouma sequence. It describes a classic set of sedimentary structures in turbiditebeds deposited by turbidity currents at the bottoms of lakes, oceans and rivers.
3. from the map the distance is 2cm , i.e 1000 km / 24Ma = 41.6 Km/Ma.
i.e 4.16 cm / yr.
4. The youngest could be even of very recent age even lesser than 1 Ma, because the MoR is the region where new crust is formed continously. The rate of movement here is 41.6 Km/Ma. The youngest crust may be some around 200 km away from the 3Ma crust. which would give some billion years of age.
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