8. Crustal Structure of the Peru-Chile Trench: 8°12° S Latitude

  1. George H. Sutton,
  2. Murli H. Manghnani,
  3. Ralph Moberly and
  4. Ethel U. Mcafee
  1. D. M. Hussong1,
  2. P. B. Edwards2,
  3. S. H. Johnson3,
  4. J. F. Campbell1 and
  5. George H. Sutton1

Published Online: 17 MAR 2013

DOI: 10.1029/GM019p0071

The Geophysics of the Pacific Ocean Basin and Its Margin

The Geophysics of the Pacific Ocean Basin and Its Margin

How to Cite

Hussong, D. M., Edwards, P. B., Johnson, S. H., Campbell, J. F. and Sutton, G. H. (1976) Crustal Structure of the Peru-Chile Trench: 8°12° S Latitude, in The Geophysics of the Pacific Ocean Basin and Its Margin (eds G. H. Sutton, M. H. Manghnani, R. Moberly and E. U. Mcafee), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM019p0071

Author Information

  1. 1

    Hawaii Institute of Geophysics, University of Hawaii, Honolulu, Hawaii 96822

  2. 2

    University of Melbourne, Parkville, Victoria 3052, Australia

  3. 3

    Oregon State University, Corvallis, Oregon 97331

Publication History

  1. Published Online: 17 MAR 2013
  2. Published Print: 1 JAN 1976

ISBN Information

Print ISBN: 9780875900193

Online ISBN: 9781118663592

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Keywords:

  • Geophysics—Pacific area—Congress;
  • Woollard, George Prior, 1908

Summary

Extensive crustal seismic data, including five reversed explosion refraction stations, an eleven-station refraction profile, twelve ASPER stations, and a multi-channel digital reflection profile, were acquired in the vicinity of the Peru-Chile trench between 8° and 12° S latitude in 1972 and 1973. The data are used to develop a complex model of the convergence of the Nazca oceanic plate with the South America contin.ental lithospheric plate. On the Nazca plate, the oceanic crust is thin and composed of rocks of higher seismic velocity than is typical of other oceanic plates. The high-density upper lithosphere may be related to the high spreading rate of the Nazca plate. Near the Peru-Chile trench large-scale compressional deformation predominates, as demonstrated by thrust faulting of the oceanic crust beneath itself prior to and possibly after subduction under the continent. Imbricate thrusting causes uplift of oceanic sediments, and perhaps upper crustal rocks, into the lower continental slope. The upper continental slope, however, appears to be of different origin. This area may be composed of continental rocks that are being fractured by vertical tectonic displacement of the trench inner wall, which is downfaulted and ultimately subducted with resultant erosion of the continental margin. The majority of oceanic rock and sediments, as well as the eroding continental rocks, are subducted and may, therefore, become source material for Andean plutonism and volcanism.