We've Moved!
Visit SDSU’s new digital collections website at https://digitalcollections.sdsu.edu
Description
A gravity survey was conducted at Langford Well Lake basin in Fort Irwin in Southern California to help determine the basement geometry. In the spring of 1996, a grid of field gravity data was collected in Langford Well Lake basin covering a 6 x 5 mile area. These data were collected and processed with the assistance of the United States Geological Survey and then compiled into a complete bouguer anomaly map. Three areas of the basin were then selected for modeling using a two dimensional gravity modeling computer program. All three sections were chosen to terminate on basement. The main section, A, is located in the middle of the basin, it mns northeast-southwest and crosses two negative gravity anomalies, the larger of which is centered on a dry lake bed, Langford Well Lake. This section was modeled using a typical density contrast between basement and the basin's sedimentary fill, then calibrated using preexisting well and seismic data. At the eastern end of Langford Well Lake the basement dips west at an angle of 21 degrees to a maximum depth of about 9 50 feet, and then gradually rises to the west until reaching the surface. An east-west cross section was created north of section A. This section, B, is asymmetrical, and, as in section A, shows the basement dipping fairly steeply on the eastern side but only to a depth of 250 feet. Section C was constructed on the west side of the study area and trends north-south. The interpretation of this cross section shows three sediment-filled channels which trend east-west between outcrops of basement. Sediments in the channels range in depth from 40 to 90 feet. The three cross sections give a reasonable idea of the basins sedimentary thickness, or the general geometry of the basin's basement.
