Sizes and ages of seamounts using remote sensing: Implications for intraplate volcanism

Science

Volumn 277, Issue 5327, 1997, Pages 802-805

  Wessel, Paul ^a  

^a NONE

Author keywords

[No Author keywords available]

Indexed keywords

DATING; INTRAPLATE ACTIVITY; REMOTE SENSING; SATELLITE ALTIMETRY; SEAMOUNT; SEAMOUNTS; SIZE; VOLCANISM;

AGE; ARTICLE; GEOLOGY; PRIORITY JOURNAL; REMOTE SENSING; SEA; VOLCANO;

PACIFIC;

EID: 0030818239     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.277.5327.802     Document Type: Article

References (41)

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3. B. H. Keating, Summary of Radiometric Ages from the Pacific (IOC Tech. Ser. 32, UNESCO, Paris, 1987), pp. 1-67.
4. Sea surface (or geoid) undulations over seamounts are small. A seamount 4 km tall may give rise to an anomaly of a few meters spread over a few hundred kilometers, making it imperceptible to human observers but easily detectable by satellite altimetry.
5. W. F. Haxby, G. D. Karner, J. L. LaBrecque, J. K. Weissel, Eos 64, 995 (1983); D. T. Sandwell, J. Geophys. Res. 89, 1089 (1984).
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14. As lithosphere ages, it cools and thickens, and is thus able to support larger seamounts. However, a variety of physical models have been proposed, including hydrostatic balance of magma pressure (for example, J. P. Eaton and K. J. Murata, Science 132, 925 (1960); P. R. Vogt, Earth Planet. Sci. Lett. 23, 337 (1974)] and control on size exerted by flexural stresses in the upper lithosphere (23) or volcano flanks [P. J. McGovern and S. C. Solomon, J. Geophys. Res. 98, 23553 (1993)). These mechanisms all produce a general size-age relation, making it difficult to uniquely identify the primary mechanism [L. Wilson, J. W. Head, E. A. Partitt, Geophys. Res. Lett. 19, 1395 (1992)].
15. As lithosphere ages, it cools and thickens, and is thus able to support larger seamounts. However, a variety of physical models have been proposed, including hydrostatic balance of magma pressure (for example, J. P. Eaton and K. J. Murata, Science 132, 925 (1960); P. R. Vogt, Earth Planet. Sci. Lett. 23, 337 (1974)] and control on size exerted by flexural stresses in the upper lithosphere (23) or volcano flanks [P. J. McGovern and S. C. Solomon, J. Geophys. Res. 98, 23553 (1993)). These mechanisms all produce a general size-age relation, making it difficult to uniquely identify the primary mechanism [L. Wilson, J. W. Head, E. A. Partitt, Geophys. Res. Lett. 19, 1395 (1992)].
16. As lithosphere ages, it cools and thickens, and is thus able to support larger seamounts. However, a variety of physical models have been proposed, including hydrostatic balance of magma pressure (for example, J. P. Eaton and K. J. Murata, Science 132, 925 (1960); P. R. Vogt, Earth Planet. Sci. Lett. 23, 337 (1974)] and control on size exerted by flexural stresses in the upper lithosphere (23) or volcano flanks [P. J. McGovern and S. C. Solomon, J. Geophys. Res. 98, 23553 (1993)). These mechanisms all produce a general size-age relation, making it difficult to uniquely identify the primary mechanism [L. Wilson, J. W. Head, E. A. Partitt, Geophys. Res. Lett. 19, 1395 (1992)].
17. As lithosphere ages, it cools and thickens, and is thus able to support larger seamounts. However, a variety of physical models have been proposed, including hydrostatic balance of magma pressure (for example, J. P. Eaton and K. J. Murata, Science 132, 925 (1960); P. R. Vogt, Earth Planet. Sci. Lett. 23, 337 (1974)] and control on size exerted by flexural stresses in the upper lithosphere (23) or volcano flanks [P. J. McGovern and S. C. Solomon, J. Geophys. Res. 98, 23553 (1993)). These mechanisms all produce a general size-age relation, making it difficult to uniquely identify the primary mechanism [L. Wilson, J. W. Head, E. A. Partitt, Geophys. Res. Lett. 19, 1395 (1992)].
18. -1.
19. Large seamounts depress the crust, reaching an isostatic equilibrium. The shape of such flexural deformation depends on the elastic thickness of the lithosphere and the density of the sediment in the moats [A. B. Watts, J. Geophys. Res. 83, 5989 (1978)]. Because the VGG strongly attenuates long-wavelength signals, the gravitational effect of flexural subsidence beneath a seamount is largely eliminated, making the attraction of the seamount itself the dominant component of the VGG anomaly.
20. o is the maximum VGG amplitude, r is distance from the center, and d is the zero-crossing distance where VGG(d) = 0. Because VGG has a steep slope at r = d, it is much easier to detect the zero-crossing than comparable features in the geoid free-air anomaly or deflection of the vertical) (7, 6).
21. I accounted for this adjustment by using the same contour in model calculations.
22. o Equating the sum of these volumes to the numerically integrated volume inside the contour allows estimation of individual radii.
23. I found numerous linear seamount chains indicative of hot-spot volcanism and a much higher density of seamounts in the central and western Pacific; the latter also has most of the largest seamounts detected. The lowest seamount densities are found south of the Eltanin fracture zone and in the equatorial eastern Pacific.
24. I used forward modeling of plate flexure caused by Gaussian seamounts of all sizes, low-pass filtered the results to make them spectrally similar to the observed data, and estimated zero-crossings and maximum amplitudes using the same procedures as were applied to the data. The results were compiled into a two-dimensional look-up table that relates maximum VGG and d to seamount height and flank slope, which combine to yield radius.
25. The observed and predicted volumes appear to agree to within 10 to 15%, but the requirement of a Gaussian shape leads to larger errors in the seamount height and radius estimates.
26. The marine portions of the ETOPO5 data set derive from SYNBAPS [R. J. Van Wyckhouse, Tech. Rep. TR-233 (U.S. Naval Oceanographic Office, NOO-Washington, DC, 1973)] and contain numerous artifacts caused by the combination of poor data coverage, gridding of contours instead of depth soundings, and inappropriate gridding methodology [W. H. F. Smith, J. Geophys. Res. 98, 9591 (1993)].
27. The marine portions of the ETOPO5 data set derive from SYNBAPS [R. J. Van Wyckhouse, Tech. Rep. TR-233 (U.S. Naval Oceanographic Office, NOO-Washington, DC, 1973)] and contain numerous artifacts caused by the combination of poor data coverage, gridding of contours instead of depth soundings, and inappropriate gridding methodology [W. H. F. Smith, J. Geophys. Res. 98, 9591 (1993)].
28. R. A. Duncan and D. A. Clague, in The Ocean Basins and Margins, A. E. M. Nairn, F. G. Stehli, S. Uyeda, Eds. (Plenum, New York, 1985), pp. 89-121; R. D. Jarrard and D. A. Clague, Rev. Geophys. 15, 57 (1977); C. Y. Yan and L. W. Kroenke, Proc. ODP Sci. Results 130, 697 (1993).
29. R. A. Duncan and D. A. Clague, in The Ocean Basins and Margins, A. E. M. Nairn, F. G. Stehli, S. Uyeda, Eds. (Plenum, New York, 1985), pp. 89-121; R. D. Jarrard and D. A. Clague, Rev. Geophys. 15, 57 (1977); C. Y. Yan and L. W. Kroenke, Proc. ODP Sci. Results 130, 697 (1993).
30. R. A. Duncan and D. A. Clague, in The Ocean Basins and Margins, A. E. M. Nairn, F. G. Stehli, S. Uyeda, Eds. (Plenum, New York, 1985), pp. 89-121; R. D. Jarrard and D. A. Clague, Rev. Geophys. 15, 57 (1977); C. Y. Yan and L. W. Kroenke, Proc. ODP Sci. Results 130, 697 (1993).
31. J. P. Morgan, W. J. Morgan, E. Price, J. Geophys. Res. 100, 8045 (1995).
32. U. S. ten Brink, Geology 19, 397 (1991).
33. P. Wessel and L. W. Kroenke, Nature 387, 365 (1997).
34. R. D. Müller, W. R. Roest, J. Y. Royer, L. M. Gahagan, J. G. Sclater, J. Geophys. Res. 102, 3211 (1997).
35. 2 (2)
36. The flexural modeling also allowed numerical estimation of moat volumes.
37. R. Batiza, Earth Planet. Sci. Lett. 60, 195 (1982).
38. W. H. F. Smith, thesis, Columbia University (1990).
39. The Ontong Java plateau was emplaced during two distinct episodes at ∼121 Ma and ∼89 Ma [D. Bercovici and J. Mahoney, Science 266, 1367 (1994)]; the Manahiki plateau also formed at ∼123 Ma, whereas the Hess rise (90 to 100 Ma) and the MidPacific Mountains (75 to 130 Ma) have longer ranges or ages. The oldest plateau is Shatsky rise (138 to 145 Ma) [R. Larson and P. Olson, Earth Planet. Sci. Lett. 107, 437 (1991)].
40. The Ontong Java plateau was emplaced during two distinct episodes at ∼121 Ma and ∼89 Ma [D. Bercovici and J. Mahoney, Science 266, 1367 (1994)]; the Manahiki plateau also formed at ∼123 Ma, whereas the Hess rise (90 to 100 Ma) and the MidPacific Mountains (75 to 130 Ma) have longer ranges or ages. The oldest plateau is Shatsky rise (138 to 145 Ma) [R. Larson and P. Olson, Earth Planet. Sci. Lett. 107, 437 (1991)].
41. I thank W. Smith for providing the VGG grid. Supported by NSF grant EAR-9303402. School of Ocean and Earth Science and Technology, University of Hawaii, contribution no. 4517.