Physical properties of rock samples from the Butte 1 degree by 2 degrees Quadrangle, Montana

Mineral resources of the Quigg West Wilderness Study Area, Granite County, Montana

“…Gravity data are in the form of a terrain-corrected Bouguer gravity anomaly map (Hassemer and Hanna, 1982;Hassemer, 1984) and are based largely on about 50 observation points within or adjacent to the map area shown on figure 5 (Hassemer and Lidke, 1986). Aeromagnetic data are in the form of an anomaly map (U.S. Geological Survey, 1984) contoured from measurements made along flight lines in an east-west direction, spaced 1 mi apart, at a barometric elevation of 9,000 ft, and are based on 13 flight lines within or adjacent to the map area of figure 6.…”

Maps showing mineral resource assessment for skarn deposits of gold, silver, copper, tungsten, and iron in the Butte 1 degree by 2 degrees Quadrangle, Montana

“…The first condition of steep upper flanks of the rock mass can be proven only by drilling or other geophysical data. The second condition of normally directed and polarized total magnetization is supported by rock magnetic data (Hanna, 1967(Hanna, , 1969(Hanna, , 1973a(Hanna, , 1973b(Hanna, , 1977(Hanna, , 1978Hassemer and Lidke, 1986). A procedure was developed that permitted the drawing of lines around regions inferred to be underlain by significantly thick masses of plutonic or geophysically similar rock.…”

Map showing mineral resource assessment for vein and replacement deposits of gold, silver, copper, lead, zinc, manganese, and tungsten in the Butte 1° x 2° quadrangle, Montana

“…The important correlation of magnetic highs to mapped plutonic rocks can be objectively shown if it is assumed that the boundaries of a given plutonic rock mass dip steeply, at least in the shallow subsurface, and if it is assumed that the total magnetization has a direction and polarity consistent with those of the present earth's magnetic field. While the first condition of upper steep flanks of the rock mass can be proved only by drilling or other geophysical data, or both, the second condition of normally directed and polarized total magnetization is supported by rock magnetic data (Hanna, 1967(Hanna, , 1969(Hanna, , 1973a(Hanna, , 1973b(Hanna, , 1977(Hanna, , 1978Hassemer and Lidke, 1986). A procedure was used which permitted the drawing of lines which encircle regions inferred to be underlain by a significantly thick mass of plutonic or geophysically similar rock.…”

“…Although gravity anomaly data were not used directly for the drawing of lines outlining inferred plutonic rocks, these data were useful in some places for confirming occurrences of plutonic rocks, whether as lows over plutonic rocks intruded into high-density country rock or as highs over plutonic rocks flanked and (or) covered by low-density Tertiary and Quaternary sedimentary deposits. The gravity data used in the study include 2,325 observations within and immediately adjacent to the quadrangle (Hassemer, 1984(Hassemer, , 1986, of which 1,900 are new, 262 were previously made by the U.S. Geological Survey. and 163 were acquired from the nonproprietary data files of the U.S. Department of Defense.…”