| Ocean: | Pacific |
| Spreading centre type: | Unlikely to be an extinct ridge |
A study from the late 1960s (Linden 1969) suggested that the Dampier Ridge, off the eastern coast of Australia, was a possible extinct spreading ridge. The ridge is over 1000 km in length and trends toward NNW-SSE, with a similar orientation to the extinct spreading centre in the Tasman Sea. The region is complicated by numerous elongate basins (Lord Howe Basin, New Caledonia Basin and New Hebrides Basin) that have limited data to constrain their age, such as identified magnetic anomalies or absolute age constraints. The region features numerous continental fragments and extensive thinned continental crust in the Lord Howe Rise (Matthews et al., 2015), that suggests lengthy episodes of distributed extension or successive extensional phases, between northeastern Australia and Fiji.
Our review found little evidence to suggest a spreading centre formation of the Dampier Ridge and subsequent studies, such as that of Weissel and Hayes (1977) propose that the Dampier Ridge is likely to be formed of continental crust, due to its thickness and similarity to that of the Lord Howe Rise. McDougall et al. (1994) summarise studies of the Dampier Ridge and evidence that the Dampier Ridge is more likely to be a continental fragment. Due to a lack of support for an extinct ridge formation this ridge was excluded from our statistical analysis.
van der Linden, W.J.M., 1969, Extinct mid-ocean ridges in the Tasman Sea and in the Western Pacific, Earth and Planetary Science Letters, v. 6, p.483–490.
Matthews, K.J., Williams, S.E., Whittaker, J.M., Müller, R.D., Seton, M. and Clarke, G.L., 2015, Geologic and kinematic constraints on Late Cretaceous to mid Eocene plate boundaries in the southwest Pacific, Earth-Science Reviews, v. 140, p.72-107.
McDougall, I., Maboko, M. A. H., Symonds, P. A., McCulloch, M. T., Williams, I. S and Kudrass, H. R., 1994, Dampier Ridge, Tasman Sea, as a stranded continental fragment, Australian Journal of Earth Sciences, v. 41, no. 5, p.395–406.
Weissel, J. and Hayes, D. E., 1977, Evolution of the Tasman Sea reappraised, Earth and Planetary Science Letters, v. 36, p. 77-84.
