Atlantic Sea-Floor Spreading Activity 2.6 chrm wewe marine magnesk anomalis, and

Question

Atlantic Sea-Floor Spreading Activity 2.6 chrm wewe marine magnesk anomalis, and theis ages are ase on e geomagertic pelary atn hit/www.latesorg) was ued to help make this map. The red line oe the aes the locanon of the divergent bounddary the axis of the d misdean ridge wwen the Noeth mevican and Mrias Plar North American Plate CNA African Plate AF 1500km 154.3 M M25) Figure A2.6.1 The approximate great-circle distances between the points identified on the map are lissed here. The uncertainty in the distances provided is probably on the order of 10 km 1354 km 1338 km 1320 km 1279 km 2617 km 2599 km 2649 km 5107 km Gus to A Bua to Bw Cas to B I. What is the average speed at which Bi drifted away from the ridge at A during the past 67.7 Myr espressed in cm/yx? What is the average speed that Bay drifted from Acm/y which plate moved faster relative to the ndge over the past 67.7 , if either? consists of oceanic lit hosphere added along the Mid-Adantic Ridge to the North 2. The area between Cxa and B can Plate between 154.3 and 67.7 Myr. What is the average speed at which new lithosphere was added to the North American Plate along that line? cm/yr. Do the same analysis for the lithosphere between points Car and Byp What is the average speed at which new lithosphere was added to the African Plate along that line?cm/yr Which plate moved faster relative to the ridge between 154.3 and 67.7 Myr, if either?

Explanation / Answer

1.

a) Average speed at which BNA drifted away from A is ,

distance between BNA and A is given as 1338 KM

it means, the BNA is drifted away 1338 KM from A in 67.7 Myr

therefore, 67.7 x 106 yr = 1338 x 105 cm

then for 1 yr = (1338 x 105) / (67.7 x 106)

= 19.76 x 10-1 cm

= 1.976 cm/yr

= ~ 2 cm/yr

b) BAF drifted away from A

distance is 1320 KM

Time is 67.7 myr

therefore, 67.7 myr = 1320 km

BY SOLVING IT SAME AS WE SOLVED (a) THEN WE GET

= 1.949 cm/yr

= ~2 cm/yr

c) both are nearly drifting with same speed.

2.

a) distance between CNA and BNA is 1354km and the difference between their respective ages is 86.6 myr

86.6 x 106 yr = 1354 x 105 cm

therefore by solving it same like 1.(a) we get,

= 15.63 x 10-1 cm/yr

= 1.5 cm/yr

b) distance is 1279 km

and the time is ( 154.3 - 67.7 = 86.6 myr)

therefore by solving it same like 1.(a) we get,

= 14.76 x 10-1

= 1.4 cm /yr

c) the fastest average speed is for

CNA to BNA which is 1.5 cm /yr.

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