21. Magnetic Anomalies in the West Philippine Basin

  1. George H. Sutton,
  2. Murli H. Manghnani,
  3. Ralph Moberly and
  4. Ethel U. Mcafee
  1. Keith E. Louden

Published Online: 17 MAR 2013

DOI: 10.1029/GM019p0253

The Geophysics of the Pacific Ocean Basin and Its Margin

The Geophysics of the Pacific Ocean Basin and Its Margin

How to Cite

Louden, K. E. (2013) Magnetic Anomalies in the West Philippine Basin, 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/GM019p0253

Author Information

  1. Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543

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—Congresses;
  • Woollard, George Prior, 1908

Summary

We present a comprehensive collection of magnetic anomalies in the West Philippine basin together with several bathymetric profiles and nannofossil age dates for DSDP sites 290 and 291. From these data we locate symmetric magnetic anomalies that have strikes roughly parallel to the Central Basin fault. They can be identified as anomalies 17–21 if the basin originated south of the equator and opened at a rate of 41–44 mm/yr. This adds justification but not total proof for the theory that the Central Basin fault may be an extinct spreading center which slowed and then ceased spreading 40 m.y. ago. It is still possible that island-arc spreading created these anomalies, but if so, the origin and evolution of such an arc cannot be simply connected to the later development of the Parece Vela and Shikoku basins to the east. Other results show that the elevation of this region is I km lower than would be observed for similar-aged crust in the North Pacific. If the DSDP dates and our anomaly interpretations are correct, then the lack of a correspondingly large negative gravity anomaly suggests major differences between this extinct ridge and those known to be currently spreading.