Using gravity, magnetic, bathymetric and seismic
refraction data, I have constructed a geophysical cross-section
of the central part of the northern Gulf of California. The
section exhibits a crustal thickness of 18 km and features an
anomalous block of high density lower basement (3.15 g/cm³)
which probably resulted from rifting processes during the
opening of the Gulf. The magnetization of the upper
basement ranges from 0.0005 to 0.0030 emu/cm³. Three
different layers of sediments are modeled, ranging from
unconsolidated (1.85 g/cm³) to compacted (2.50 g/cm³).
I present a deconvolution method for automated
interpretation of magnetic profiles based on Werner's (1953)
simplified thin-dike assumption, leading to the linearization
of complex nonlinear magnetic problems. The method is
expanded by the fact that the horizontal gradient of the total
field caused by the edge of a thick interface body is
equivalent to the total field of a thin dike. Statistical decision
making and a seven point operator are used to insure good
approximations of susceptibility, dip, depth, and horizontal
location of the source. After using synthetic models to test
the inversion method, I applied it to the Northern Gulf of
California using data collected in 1984 by the Continental
Margins Study Group at Oregon State University. Fault traces,
computed by the deconvolution, are plotted on a map. The
faulting pattern obtained is in good agreement with that
proposed by other workers using other methods. The depths
to the top of the faults range from 4 to 5 km in the eastern
part of the Gulf, where they may be interpreted as the top of
the structural basement. Deeper estimates are obtained for
the western part of the Gulf. / Graduation date: 1990
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/29154 |
| Date | 09 June 1989 |
| Creators | Doguin, Pierre |
| Contributors | Couch, Richard W. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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