Principal facts for gravity profiles collected near the Osgood Mountains and the Slumbering Hills, north-central Nevada

Abstract

The digital data, text of this report (figures in separate files) can be downloaded via 'anonymous ftp' from a USGS system named greenwood. cr.usgs.gov (136.177.21.122). The files are located in a directory named /pub/open-file-reports/ofr-97-0085 and are described in an ASCII file named readme.txt. This information is also contained below in Table 1. coverage of the airborne data would have been prohibitively expensive. The profiles collected for Battle Mountain Gold were part of the company's exploration program.Ground-based electrical, magnetic, and gravity data collected before the airborne surveys were flown are presented in Abrams and others (1984), Reran and Smith (1984), Reran andMcCafferty (1986), and others (1984;. The gravity data reported in Abrams and others (1984) are partly superseded by the profile data presented here (discussed below).The Getchell digital airborne geophysical data were originally released through the U.S. Department of Commerce's National Geophysical Data Center in February, 1989. Digital grids of many of these data sets are contained in Grauch and others (1993), along with interpretative grids and descriptions of the survey specifications and data files. Other publications related to the airborne geophysical demonstration project include Hoover and others (1991), who reviewed preliminary results of all the airborne surveys; Pitkin, (1991, gamma-ray data); Grauch and Bankey, (1991, aeromagnetic data); and Pierce and Hoover (1991, electromagnetic data). Maps at 1:100,000 scale and brief discussions of the aeromagnetic and electromagnetic data are presented in Grauch and Bankey (1994) and Wojniak and others (1994), respectively. Further discussions of the data are contained in Grauch and others (1991), . DATA COLLECTIONGravity measurements were acquired along profiles IP (Iron Point), FMG (FirstMiss Gold), and OC (Osgood Creek) by the USGS in 1989; along profile SR (south regional) by the USGS in 1990 and 1993; and along profiles LB1, LB2, LB3, FM2, and FM3 by Mining Geophysical Surveys for Battle Mountain Gold Company in 1989. Locations of these profiles are shown in Figures 2 and 3. Data descriptions for the profiles collected by the USGS and those collected by Mining Geophysical Surveys are described separately below. USGS ProfilesData for profiles IP, FMG, and OC were acquired using LaCoste-Romberg gravity meter G-2 in 1989. Data for profile SR were collected in 1990 using LaCoste-Romberg gravity meter G-550 and in 1993 using LaCoste-Romberg gravity meter G-191. The hiatus in data collection of profile SR was caused by equipment failure and scheduling difficulties.Locations along all profiles were surveyed using a Hewlett-Packard total station. The profile lines were initially planned to match as closely as possible the location and orientation (about N58°W) of the extra-long flight lines in the airborne/electromagnetic survey (Grauch and Bankey, 1994). Reference positions along the profiles were determined by triangulation from points with known control, such as benchmarks, ...