1intact volcanic rocks of age 300 Ma are found in continental lava flows at a si

Question

1intact volcanic rocks of age 300 Ma are found in continental lava flows at a site with geographic latitude 55 degree north. the magnetic inclination of the rocks is found to be 15 degree. Assuming an axially aligned paleo-dipole, estimate the amount of northward continental drift implied by the above data

2a detailed plate-tectonic reconstruction gives a Northward continental drift for the site above that differs from Northward motion implied by the geographic latitude and magnetic inclination. Give two possible reasons for this discrepancy.

Explanation / Answer

we know that,

Tan(I) = 2Tan ( ?)

where I is the mgnetic inclination

? is the paleolattitude

thus, Tan 15 /2 =Tan ?

?= 7.632,

therefore the northward continental drift is 55 degree(present latitude) - 7.632 (paleolatitude)

=47.368 degrees.

2. the site above this differs from orthward motion due two possible reason:

a)may be that sight was in a different plate and moved differently.

b)the sight was formed at different geologic time with different magnetic field prevailling that time causing difference in magnetic inclination

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