Geophysical data collected in 1975 and 1976 reveal major
crustal and tectonic elements of the continental margin of southern
Baja California. Gravity, magnetic, seismic reflection and bathymetric data show seaward extension of the islands enclosing Magdalena
and Almejas Bays. A seismic reflection profile, oriented
approximately normal to the trend of the Baja peninsula, indicates
normal faulting of the near surface sediment layers along the outer
continental shelf. The reflection record also shows that sediment
layers immediately above the acoustic basement dip toward the east
at the base of the continental slope. A crustal and subcrustal cross
section, oriented approximately parallel to the reflection profile and
constrained by gravity, magnetic, bathymetric and seismic refraction
data, indicates a maximum crustal thickness of approximately 21 km
for Baja California, making it intermediate in thickness between
normal continental and normal oceanic crusts. The section also indicates a low density zone in the mantle below the Gulf of California.
Magnetic anomalies along the cross section require oceanic crust of
the Pacific Plate to extend at least 50 km landward of the edge of the
western continental shelf of Baja California. This suggests either
a past period of oblique subduction of the Pacific Plate beneath Baja
California or emplacement of Pacific Plate oceanic crust beneath the
peninsula by descending spreading centers of the East Pacific Rise. / Graduation date: 1977
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/29137 |
| Date | 28 April 1977 |
| Creators | Huehn, Bruce |
| Contributors | Couch, Richard W. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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