Part l: Plate Tectonics OBJECTIVE-To do a simple calculation of the rate of plat

Question

Part l: Plate Tectonics OBJECTIVE-To do a simple calculation of the rate of plate motion. You will need a ruler that has mm. Rulers will be available in Study Groups Determine seafloor spreading rate over the past 30 million years for the Southeast Indian Rise. In this exercise, you will use ages of oceanic crust in the southeast Indian Ocean to determine the rate of spreading at the Southeast Indian Rise, which separates Australia from Antarctica. The map on the last page shows ages of oceanic crust for the Australian-Indian and Antarctic plates in the southeast Indian Ocean. The position of the Southeast Indian Rise is indicated by the dark line. Oceanic crust that is less than 30 million years old is white, while older crust is shaded in gray. 1. Use the scale on the map on the last page to determine the width of oceanic crust that is younger than 30 million years old (white) on the Australian-Indian Plate measured from the Southeast Indian Rise. Write that distance below with units shown (look at scale to determine units). Remember to measure from the ridge (bold line in the middle of the white) to the edge of the white 2. Divide the measured distance by 30 million years to calculate the rate in km/m.y at which the Australian-Indian Plate is being created at the Southeast Indian Rise. SHOW YOUR WORK, INCLUDING UNITS. 3. An approximately equal amount of Antarctic plate is generated on the opposite side of the Southeast Indian Rise. Now determine the total rate of seafloor spreading at the Southeast Indian Rise (hint: multiply by what?). 4. Using the conversion 1 km/m.y. 1 mm/yr, convert the seafloor spreading rate to mm /yr. Write what the spreading rate is in mm/yr below.

Explanation / Answer

Ans 1) Width of the plate younger than 3My = 1000 km

Ans 2) Rate of half spreading = Distance/Time

= 1000 km / 30 My

= 33.33 km/ My

Ans 3) Total rate of spreading = 2 × rate of half spreading

= 2 × 33.33 km/ My

= 66.66 km / My

Ans 4) Total spreading rate = 66.66 km/ My

= 66.66 × 10^6 mm/ 10^6 year

= 66.66 mm/year.

Ans 5) Just draw a line of 6.67 cm

Ans 6) The left box is divergent plate boundary.

The right box is convergent plate boundary.

Explanation- The region of thin oceanic crust where two plates move away from each other are called divergent plate boundaries. Similarly, region where a plate gets subducted beneath the other, its called a convergent plate boundary.

Ans 7) At D <==>

Near E =><=

Explanation- At d two plates move apart and at E two plates move towards each other.

Ans 8) Igneous - D, G and F

Sedimentary- C and E

Metamorphic- F

Explanation- Igneous rocks are found at places with active volcanism like mid oceanic ridges or overriding plates.

Sedimentary rocks are found along slopes near water bodies.

Metamorphic rocks need high pressure and temperature found near subduction zone.

We were glad to answere this question. Let us know if you have any further queries. Do like the answere if you were satisfied.

Regards.

Related Questions

Navigate

• Browse (All)
• Browse P
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.