We can calculate an average rate of seafloor spreading by measuring the distance

Question

We can calculate an average rate of seafloor spreading by measuring the distance between MOR's, then divide the distance by the and age of seafloor rocks collected there (e.g. such as from ODP cores).   Recall:  Rate (r) = Distance (d) ÷ Time (t)    or    r = d / t

1. What is the average spreading rate of the Atlantic Ocean basin measured along the Equator?  Use the outer edge of the continents of S America and Africa to determine the edge of the oceanic plate.  The oldest ocean floor, basalt rocks collected at the base of the continental shelf are midCretaceous in age. (Show your calculations below)

2. What is the average 'half spreading rate' measured from the MOR to the continental margin of the Pacific Ocean basin along the Equator?  Measure from the East Pacific Rise to the continental margin in the western Pacific Basin.  The oldest seafloor, basalt rocks collected here are midJurassic in age. (Show your calculations below)

http://www.science.earthjay.com/instruction/CR_eureka/GEOL_15/lecture_05/geol_15_activity_2.pdf

Explanation / Answer

1. The distance trveled by the North American plate from the African plate from the mid cretaceous( approximately 90my) age is 225 km.

so the half spredding rate of the Antlantic ocean basin is r = d / t

here d = distance trveled by the plate = 2250km

t = time = 90 my

r 1/2= 2250 / 90

= 25 km / my

It is equal r1/2 = 2.5 cm / year

the full spreadding rate of atlantic basin r = r1/2 *2

= 25*2 = 50km / my

i.e equals to r = 5 cm / year

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