Gravity Data in the eastern Mojave Desert, California and Nevada

The U.S. Geological Survey (USGS) collected gravity data in the eastern Mojave Desert, California and Nevada as an aid to characterizing the regional geologic framework. Gravity stations were located between approximately lat 35°10’ and 35°50’ N. and long 115°05’ and 115°50’ W. and were distributed from west to east across parts of Shadow Valley, Clark Mountain Range, Mescal Range, Ivanpah Valley, Lanfair Valley, Bobcat Hills, and New York Mountains. Gravity data were ultimately tied to a World Relative Gravity Reference Network of North America gravity base station at Nipton, California (Jablonski, 1974) and supersede previously published data (Denton and Ponce, 2018). In general, gravity anomalies can be used to infer the subsurface structure of geologic features, provided a physical-property contrast occurs across the geologic boundaries. Gravity anomalies can, for example, reveal variations in lithology and delineate features such as calderas, deep sedimentary basins, and faults, all of which play an important role in defining the geologic framework of a region (Ponce and Denton, 2018). Gravity data were processed using standard geophysical methods (for example; Blakely, 1995; Denton and Ponce, 2018). New gravity data are shown at the top of the data file and their reduction method matches previously published data. Gravity data include the following corrections: (1) earth-tide correction, which corrects for tidal attraction of the Moon and Sun; (2) instrument-drift correction, which compensates for drift in the instrument’s spring; (3) latitude correction, which accounts for variation in the Earth’s gravity with latitude; (4) free-air correction, which accounts for variation in gravity due to elevation relative to sea level; (5) Bouguer correction, which corrects for the attraction of material between the station and sea level; (6) curvature correction, which corrects the Bouguer correction for the effect of the Earth’s curvature; (7) terrain correction, which removes the effect of topography to a radial distance of 167 km from the station; and (8) isostatic correction, which removes long-wavelength variations in the gravity field related to the compensation of topographic loads. Denton, K.M., and Ponce, D.A., 2018, Gravity and magnetic studies of the eastern Mojave Desert, California and Nevada (rev. 1.1): U.S. Geological Survey Open-File Report 2016-1070, 20 p., https://doi.org/10.3133/ofr20161070. Jablonski, H.M., 1974, World relative gravity reference network North America, Parts 1 and 2, with a supplementary section on IGSN 71 gravity datum values (rev. ed.): U.S. Defense Mapping Agency Aerospace Center Reference Publication 25, 1261 p. Ponce, D.A., and Denton, K.M., 2018, Isostatic gravity map of Mountain Pass and vicinity, California and Nevada: U.S. Geological Survey Scientific Investigations Map 3412-A, 6 p., scale 1:62,500, https://doi.org/10.3133/sim3412A.