Part 4: Determing Plate Velocity From Hot Spot Tracks The Emperor-Hawaii volcani
ID: 120149 • Letter: P
Question
Part 4: Determing Plate Velocity From Hot Spot Tracks The Emperor-Hawaii volcanic chain reaches from the Hawian Islands to the Aleutia Islands in Alaska. Below is a map showing the volcanic chain and the ages of the volcanoes. Many geologists believe that there are plumes in the Earth's mantle, that are relatively fixed, which create "hot spots" on the surface. As a lithospheric plate moves over the mantle plume, volcanoes erupt leaving a trail of volcanic rocks behind and a "hot spot track". The rate of plate motion for the Pacific plate can be calculated by measuring the distance between dated volcanoes and dividing by the age difference. 4.9 5.1 Aleutian 1-27. Trench NIHAU 3.7 Suko : 8 Seamount 59.6 MOLOKA Honc ulu 1.9 1.3 LANAI MAUI Nintowu Sesmount 56.2 0 43 0.8 0.38 Jingu The eight principal siands Seamountof the Hawaien Archipe ago 55 4 55.2 0.01 0.004 Yuryaku Lohi Guyot 48.1 30 43.4 Midway 272 / ear & Root Hemes Roct 20.6 Dakakui Saamount 42 4 Laysan 199 La Porouse Pinnacle Necker 120 10.3 Nihau Moloka Maui Hawai 150 152 (Note that the scale on the lower map is 1 cm 400 km) (Image from www.hawai-guide.com/images/body_images/misc-hawaiian_archipelago.jpg) What was the rate of Pacific plate motion relative to a stationary hot spot from 42.4 m.y. to 59.6 m.y.? 1. Did the rate of the Pacific plate motion change when the direction changed after 42.4 m.y.? If so, by how much? (Use the ages between 42.4 and 10.3 m.y.) 2.Explanation / Answer
1. Rate of pacific plate movement relative to stationary hot spot from 42.4 m.y. to 59.6 m.y.:
Time in million year = 59.6 m.y. - 42.4 m.y. = 17.2 m.y. or 17.2 x 106 years
Displacement of pacific plate = 3 centimeter on map = 3 x 400 kilometer = 1200 kilometer = 1200 x 105 centimeter
Rate of pacific plate movement relative to stationary hot spot from 42.4 m.y. to 59.6 m.y. = (1200 x 105 / 17.2 x 106)
Rate of pacific plate movement relative to stationary hot spot from 42.4 m.y. to 59.6 m.y. = 6.9767 centimeter/year
2.
Displacement of pacific plate = 4.7 centimeter on map = 4.7 x 400 kilometer = 1880 kilometer = 1880 x 105 centimeter
Time in million year = 42.4 m.y. - 10.3m.y= 32.1 m.y. or 32.1 x 106 years
Rate of pacific plate movement relative to stationary hot spot from 42.4 m.y. to 10.3m.y = (1880 x 105 / 32.1x 106)
Rate of pacific plate movement relative to stationary hot spot from 42.4 m.y. to 10.3m.y = 5.8566 centimeter/year
Yes, the speed change by (6.9767 - 5.8566) = 1.1200 centimeter/year
3.
Time in million year = 5m.y= 5 x 106 years
Displacement of pacific plate = (6 centimeter on map/ 2.6) x 150 = 346.15 kilometer =346.15 x 105 centimeter
Rate of pacific plate movement = (346.15 x 105 / 5 x 106)
Rate of pacific plate movement = 6.9230 centimeter/year
4. The rate of movement of North atlantic plate is not known, hence can't compare it with Rate of movement pacific plate movement.