Abstract
As the quantity of seismic refraction data in the oceans increases it is becoming apparent1ā3 that there is a systematic increase in crustal thickness with age, at least out to about 60 Myr (refs 1,2). To explain this phenomenon more precisely the detailed structure of the lower crust is required. We present seismic refraction data from the Northern Cocos plate which shows that thickening occurs by the formation of a low velocity zone (LVZ) at the base of the crust with a velocity < 6.8 km sā1. One possible explanation of this in terms of these relatively low seismic velocities for the lower crust4, is that upper mantle material becomes serpentinised by a hydration reaction as it cools. If so, this implies that the Moho boundary, except at very young ages, is a phase change (hydration) boundary. This supports the ideas of Hess5.
This is a preview of subscription content, access via your institution
Access options
Subscribe to this journal
Receive 51 print issues and online access
$199.00 per year
only $3.90 per issue
Buy this article
- Purchase on Springer Link
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
References
Goslin, J., Benzart, B., Francheteau, J. & LePichon, X. Mar. Geophys. Res. 1, 418ā427 (1972).
Woollard, G. P. Rev. Geophys. 13(1), 87ā138 (1975).
Shor, G. G., Jr., Menard, H. W. & Raitt, R. W. in The Sea Part 2 (ed. Maxwell, A. E.), 3ā27 (1970).
Christensen, N. I. & Salisbury, M. H. Rev. Geophys. 13(1), 57ā86 (1975).
Hess, H. H. in Petrologic Studies (eds Engel, A. E. J., James, H. & Leonard, B. F.) 599ā620 (Geological Society of America, New York, 1962).
Sclater, J. G., Anderson, R. N. & Bell, M. L. J. geophys. Res. 76, 7888ā7907 (1971).
Snydsman, W. E., Lewis, B. T. R. & McClain, J. Earth planet. Sci. Lett. 28, 46ā50 (1975).
Parker, R. L. & Oldenburg, D. W. Nature 242, 137 (1973).
Helmberger, D. V. & Morris, G. B. J. geophys. Res. 74(2), 483ā494 (1969).
Orcutt, J., Kennett, B., Dorman, L. & Prothero, W. Nature 256(5517), 475ā476 (1975).
Fuchs, K. & MĆ¼ller, G. Geophys. J. R. astr. Soc. 23, 417ā433 (1971).
Kennett, B. L. N. Geophys. J. R. astr. Soc. 42, 579ā589 (1975).
Lister, C. R. B. Geophys. J. R. astr. Soc. 39, 465ā509 (1974).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
LEWIS, B., SNYDSMAN, W. Evidence for a low velocity layer at the base of the oceanic crust. Nature 266, 340ā344 (1977). https://doi.org/10.1038/266340a0
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1038/266340a0
This article is cited by
-
Density of the ocean crust
Nature (1984)
-
Crustal low-velocity zone south of Shatsky Rise, northwest Pacific Ocean
Geo-Marine Letters (1982)
Comments
By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.