Abstract:
This thesis is a collection and analysis of seafloor
magnetic anomalies, bathymetry, and the paleomagnetism
of DSDP sediments and basalt in the West Philippine Basin,
in an attempt to resolve questions about its origin as a
marginal basin. Our results suggest that this basin was
formed in an Eocene pulse of rapid spreading (v1/2 = 41-44 mm/yr)
in a direction (N 21°E) significantly different from later
pulses which opened the more eastern basins of the Philippine
Sea. The Central Basin Fault appears to be intimately
associated with this spreading by nature of its structure
and trend, and it may be a remanent of a former ridge system.
Our preliminary calculation of paleopole positions also
suggests that there was a large amount (60°) of clockwise rotation between this basin and the magnetic pole. This is
consistent with rotations of the Pacific plate with respect
to the magnetic pole and current directions of Philippine-
Pacific'relative rotations. Basement depths of 6 km in the
West philippine Basin imply that its crustal and/or lithospheric
structure is different from Pacific structure of the
same age.
