Geoscience Reference
In-Depth Information
(a)
central volcano
inner wall
inner wall
central volcano
inner wall
central shield volcano
inner wall
summit
rift
500 m
100 m
100 m
1
1
1
0
0
0
1 km
1 km
1 km
Fast
Intermediate
Slow
(b)
Figure 9.15. (a) Schematic diagrams to show the major differences in the axial
morphology amongst fast-, intermediate- and slow-spreading mid-ocean ridges. As
the spreading rate decreases, the height of the normal-faulted inner wall increases
and the central volcano ceases to be a continuous feature. The vertical is
exaggeration is 2 : 1. (After Macdonald (1982)). Reprinted, with permission, from the
Annual Review of Earth and Planetary Sciences , volume 10 c 1982 by Annual
Reviews www.annualreviews.org.) (b) A three-dimensional bathymetric image of the
Rodriguez or Indian Ocean triple junction (Fig. 2.2) looking towards the west. This is
the RRR triple junction (Fig. 2.16) where the Antarctic, Australian and African plates
meet. The very-slow-spreading Southwest Indian Ridge (top of image) has a deep
rift valley and uplifted rift flanks. The two intermediate-spreading ridges, the
Southeast Indian Ridge (left of image) and the Central Indian Ridge (right of image),
have almost the same north-south strike, and are broad and regular. The image
covers approximately 90 km × 90 km. Colour version Plate 18. (N. J. Mitchell 1989
data collected by M. Munschy and R. Schlich, IPG Strasbourg, France.)
 
Search WWH ::




Custom Search