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Morphological Interpretation of Seamounts in American Samoa:

Morphological Interpretation of Seamounts in American Samoa: Inferring Genesis Mechanisms through Shape and Distribution Analysis. Jed Roberts Master’s Candidate in Geography Department of Geosciences Oregon State University AAG San Francisco - April 19, 2007. Presentation Overview.

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Morphological Interpretation of Seamounts in American Samoa:

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  1. Morphological Interpretation of Seamounts in American Samoa: Inferring Genesis Mechanisms through Shape and Distribution Analysis Jed Roberts Master’s Candidate in Geography Department of Geosciences Oregon State University AAG San Francisco - April 19, 2007

  2. Presentation Overview

  3. Study Area Image produced by the U.S. National Park Service

  4. Study Area Eastern Volcanic Province (American Samoa) Western Volcanic Province (Samoa) Image produced by the U.S. National Park Service

  5. Why This Study Area?

  6. Tectonic Setting Image modified from Sandwell and Smith

  7. Controversy Artwork by Jayne Doucette, Woods Hole Oceanographic Institution Artwork by Naoto Hirano, Scripps Institution of Oceanography

  8. Research Questions

  9. Data Description

  10. Multibeam Data Merged with Sandwell and Smith 1km resolution predicted bathymetry Image created using Fledermaus Data source: The Seamount Catalog www.earthref.org

  11. Multibeam Data With 210m resolution swaths isolated Image created using Fledermaus Data source: The Seamount Catalog www.earthref.org

  12. Methods | Identifying Seamounts

  13. Methods | Identifying Seamounts Slope Surface Map created in Fledermaus Data source: The Seamount Catalog www.earthref.org

  14. Methods | Identifying Seamounts 51 Seamounts Selected Map created in Fledermaus Data source: The Seamount Catalog www.earthref.org

  15. Methods | Characterizing Seamounts

  16. Methods | Characterizing Seamounts Plan View Cross-sectional View Images created in Fledermaus

  17. Methods | Characterizing Seamounts Azimuth Angle Summit Width Slope Right Slope Left Height Base Width Base Depth Images created in Fledermaus

  18. Methods | Seamount Statistics

  19. Results | Seamount Statistics

  20. Results | Relational Statistics

  21. Results | Relational Statistics

  22. Results | Relational Statistics

  23. Results | Relational Statistics

  24. Results | Relational Statistics

  25. Results | Relational Statistics

  26. Results | Relational Statistics

  27. Results | Relational Statistics

  28. Methods | Distribution Analysis

  29. Methods | Distribution Analysis

  30. Methods | Distribution Analysis 100-600 m range

  31. Methods | Distribution Analysis

  32. Methods | Distribution Analysis Calculation of Area by -2640 m Cutoff Total area before depth cutoff: 27,181 km2 Total area after depth cutoff: 22,745 km2 Map created in Fledermaus Data source: The Seamount Catalog www.earthref.org

  33. Results | Distribution Analysis ν0 = 2.6 ± 0.2 (per 1000 km2) ß-1 = 138 m

  34. Results | Distribution Analysis ASSC is the American Samoa Seamount Chain, MAR is the Mid-Atlantic Ridge, ESC is the Easter Seamount Chain, EPR is the East Pacific Rise

  35. Results | Interpretation

  36. Results | Interpretation Directional Trends Map created in Fledermaus Data source: The Seamount Catalog www.earthref.org

  37. Significance

  38. Future Work

  39. Acknowledgements

  40. References Abers, G. A., Parsons, B., and Weissel, J. K. 1988. Seamount abundances and distributions in the southeast Pacific. Earth and Planetary Science Letters. 87: 137-51. Bemis, K. G., and Smith, D. K. 1993. Production of small volcanoes in the Superswell region of the South Pacific. Earth and Planetary Science Letters. 118: 251-62. Hart, S. R., Staudigel, H., Koppers, A. A. P., Blusztajn, J., Baker, E. T., Workman, R., Jackson, M., Hauri, E., Kurz, M., Sims, K., Fornari, D., Saal, A., and Lyons, S. 2000. Vailulu'u undersea volcano: The New Samoa. Geochemistry Geophysics Geosystems. 1(12): 2000GC000108. Hart, S. R., Coetzee, M., Workman, R. K., Blusztajn, J., Johnson, K. T. M., Sinton, J. M., Steinberger, B., and Hawkins, J. W. 2004. Genesis of the Western Samoa seamount province: age, geochemical fingerprint and tectonics. Earth and Planetary Science Letters. 227: 37-56. Hirano, N., Takahashi, E., Yamamoto, J., Abe, N., Ingle, S.P., Kaneoka, I., Hirata, T., Kimura, J., Ishii, T., Ogawa, Y., Machida, S., and Suyehiro, K. 2006. Volcanism in Response to Plate Flexure. Science. 313: 1426-28. Jaroslow, G. E., Smith, D. K., and Tucholke, B. E. 2000. Record of seamount production and off-axis evolution in the western North Atlantic Ocean, 25º25'-27º10'N. Journal of Geophysical Research. 105(B2): 2721-36. Kleinrock, M. C., and Brooks, B. A. 1994. Construction and destruction of volcanic knobs at the Cocos-Nazca spreading system near 95ºW. Geophysical Research Letters. 21(21): 2307-10. Magde, L. S., and Smith, D. K. 1995. Seamount volcanism at the Reykjanes Ridge: Relationship to the Iceland hot spot. Journal of Geophyical Research. 100(B5): 8449-68.

  41. References Natland, J. H. 1980. The progression of volcanism in the Samoan linear volcanic chain. American Journal of Science. 280-A: 709-35. Natland, J. H. 2004. The Samoan Chain: A Shallow Lithospheric Fracture System. www.mantleplumes.org (last accessed March 11, 2006). Rappaport, Y., Naar, D. F., Barton, C. C., Liu, Z. J., and Hey, R. N. 1997. Mophology and distrubution of seamounts surrounding Easter Island. Journal of Geophysical Research. 102(B11): 24,713-28. Scheirer, D. S., and Macdonald, K. C. 1995. Near-axis seamounts on the flanks of the East Pacific Rise, 8ºN to 17ºN. Journal of Geophysical Research. 100(B2): 2239-59. Scheirer, D. S., MacDonald, K. C., Forsyth, D. W., and Shen, Y. 1996. Abundant Seamounts of the Rano Rahi Seamount Field Near the Southern East Pacific Rise , 15º S to 19º S. Marine Geophysical Researches. 18: 13-52. Smith, D. K. 1988. Shape analysis of Pacific seamounts. Earth and Planetary Science Letters. 90: 457-66. Smith, D. K., and Jordan, T. H. 1988. Seamount Statistics in the Pacific Ocean. Journal of Geophysical Research. 93(B4): 2899-918. Smith, D. K., and Cann, J. R. 1990. Hundreds of small volcanoes on the median valley floor of the Mid-Atlantic Ridge at 24º-30º N. Nature. 348: 152-5. Smith, D. K., and Cann, J. R. 1992. The Role of Seamount Volcanism in Crustal Construction at the Mid-Atlantic Ridge (24º-30ºN). Journal of Geophyical Research. 97(B2): 1645-58.

  42. References Walker, G. P. L., and Eyre, P. R. 1995. Dike complexes in American Samoa. Journal of Volcanology and Geothermal Research. 69: 241-54. Workman, R. K., Hart, S. R., Jackson, M., Regelous, M., Farley, K. A., Blusztajn, J., Kurz, M., and Staudigel, H. 2004. Recycles metasomatized lithosphere as the origin of the Enriched Mantle II (EM2) end-member: Evidence from the Samoan Volcanic Chain. Geochemistry Geophysics Geosystems. 5(4): 2003GC000623.

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