Bouguer Gravity Anomalies and Crustal Structure in Northwestern Mexico
Robert Wayne Schellhorn, Carlos L. V. Aiken, Mauricio F. de la Fuente, 1991. "Bouguer Gravity Anomalies and Crustal Structure in Northwestern Mexico", The Gulf and Peninsular Province of the Californias, J. Paul Dauphin, Bernd R. T. Simoneit
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A new Bouguer gravity anomaly map has been produced for northern Mexico using approximately 15,000 new gravity stations observed over the last 10 years. An analysis of the trend surfaces of elevations and Bouguer gravity anomalies were used to predict regional Bouguer gravity anomalies from topography resulting in residual/isostatic maps. From these maps, no recognizable offset is observed in the location of a proposed Mojave-Sonora megashear, although a crustal boundary is indicated by a change in trend or truncation of various features in northwestern Sonora. Also these maps show possible trends of trench-related features in the Baja region which continue the length of Baja and apparently are not offset by major transverse structures. Three crustal models were generated using previous seismic control. These models indicate that the crust in the Gulf of California region is approximately 10 km thick, whereas the crust in the Sierra Madre Occidental is more than 50 km thick. The lithosphere is approximately 10 km thick over the Baja rift and more than 95 km thick in the area of the Sierra Madre Occidental.
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The Gulf of California is an excellent laboratory for studying sedimentary processes on time scales that are not resolvable in the open ocean. The high biological productivity and the unique physical character of the gulf combine to produce sedimentological processes that preserve annual phenomena. This volume is organized into six sections. Part 1 covers historical exploration of the area. Part 2 includes 5 chapters detailing information contained on the 5 fold-out maps that accompany the volume. Part 3 consists of chapters on regional geophysics and geology. Part 4 covers satellite geodesy. Part 5's seven chapters discuss physical oceanograpy, primary productivity, and sedimentology. Part 6 covers hydrothermal processes.