Page 138 - Global Tectonics

124 CHAPTER 6

(a) 1

Rise
0

Axial relief (km) 1 Rift

2

Slow Int. Fast
3

(b) 10

8
Seismic crust (km) 6 Fast

4

2 Slow

Ultraslow
0
0 20 40 60 80 100 120 140 160
Full spreading rate (mm yr )
1
Fig. 6.3 (a) Axial relief and (b) seismic crustal thickness as a function of full spreading rate at mid-ocean ridge crests.

A ridge classification scheme is shown by the heavy black straight lines which indicate the spreading rate ranges for

ultraslow, slow, fast and two intermediate classes (modified from Dick et al., 2003, with permission from Nature 426,
405–12. Copyright © 2003 Macmillan Publishers Ltd).