Data collected by personnel of the Geophysics Group at Oregon State
University and the Instituto Oceanografico of the Direccion General dé
Oceanografia are used to construct a free-air anomaly map for the central
part of the Pacific continental margin of Mexico, which shows the gravity
expression of major structural features in the region. Specific features
are the Middle America and Rivera trenches intersected by a possible extension
of the Rivera Fracture Zone, and the Ulloa Trough on the western
side of Baja California. Of particular importance are gravimetric minimums
with no bathymetric expression observed east of the Tres Marias
Islands, southeast and northwest of the Tamayo Fracture Zone, and as extensions
of the bathymetrically mapped series of en echelon faults within
the Gulf of California.
A geophysical model cross section constructed along a profile southeast
of the Tres Marias Islands indicates a continental type crust east
of the islands with a Moho depth of 13 km at the base of the Tres Marias
Scarp and dipping toward the continent. The structure at the transition
zone between oceanic and continental crust suggests active subduction of
the oceanic crust in the past followed by a period of shear or strike-slip
motion. The thickness of the sediments along the cross section and
east of the Tres Marias Islands reaches 1.5 km. / Graduation date: 1981
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/28996 |
| Date | 27 February 1981 |
| Creators | Sanchez Zamora, Osvaldo |
| Contributors | Couch, Richard W. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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