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David F. Barnes

Publications and source records attributed to David F. Barnes.

At least 19 recordsLinked to original sources
USGS2011

Standardization of gravimeter calibrations in the geological survey

The calibration of gravimeters has long been primarily the concern of geodesists involved in measuring large gravity differences, but recent developments suggest that the precision and stability of gravimeter calibrations may have greater geologic importance in the future. First, the use of high-speed computers and an increasing variety of supplemental data now make possible the geologic interpretation of gravity anomalies so small that they would not have been noticed in surveys made ten years ago. The kind of gravity interpretation that identifies small reefs and local accumulations of petroleum [ McCulloh , 1967] often requires local increases in station density and the assurance that the calibration of meters used in all parts of a survey are compatible. Second, temporal changes of gravity have already been measured in connection with earthquakes [ Barnes , 1966], volcanic eruptions [ Iida et al , 1952], and the movement of ice caps [ Behrendt , 1967]; they are now being considered for several other types of geologic processes.

Alaska, Arizona, California, Colorado, Oregon, Was↗
USGS2011

Progress on a gravity map of Alaska

The U.S. Geological Survey began gravity surveys in Alaska ten years ago with local surveys in the Copper River and Tanana Basins. Shortly before the 1963 AGU gravity symposium [ Barnes , 1965], the emphasis shifted from local surveys to the preparation of a reconnaissance gravity map of the whole state with a 10-mgal contour interval on a scale of 1:2,500,000, which would be similar to the gravity map of the United States [ Woollard and Joesting , 1964]. Data have now been obtained in approximately three-fourths of the state, but there are large variations in both station density and geologic usefulness of the coverage. The amount of coverage is primarily influenced by the distribution of water bodies because more than three-fourths of the stations have been obtained by riverboats, small skiffs, and floatplanes.

Alaska↗
USGS1979

Geologic interpretation of the gravity anomaly map of the Seward and Blying Sound quadrangles, Alaska

For more than 20 years, gravity surveys have been conducted in the vicinity of Prince William Sound, the epicentral region of the great Alaska earthquake of March 27, 1964. Some of the major regional gravity anomalies were outlined by Thiel, Ostenso, Bonini (1960), and additional anomalies were defined by pre- and post-earthquake gravity studies reported by Barnes and Allen (1965) and Case, Barnes, Plafker, and Robbins (1966). Another gravity anomaly map was prepared by personnel of the U.S. Coast and Geodetic Survey (now the National Oceanic and Atmospheric Administration) (Wood, 1966, p. 131; Rice, 1969, p. 5-20). Anomalies shown by Rice (1969) are broadly similar to those shown by Case, Barnes, Plafker, and Robbins (1966); Rice's interpretations concerned mainly gravity changed related to the earthquake, and the data were not interpreted in terms of regional geology. New gravity stations were established in 1976 as part of the mineral resource appraisal of the Seward and Blying Sound quadrangles. This report incorporates the new data obtained in 1976, reinterprets some anomalies previously discussed by Case, Barnes, Plafker, and Robbins (1966), and interprets other anomalies not previously discussed. Descriptions of the major rock units and structural features are found in the companion report by Tysdal and Case (in press). An interpretation of the aeromagnetic map of the region has been prepared by Case, Tysdal, Hillhouse, and Gromme (1979).

Alaska↗
USGS1975

Gravity map of the Nabesna Quadrangle, Alaska

The gravity map of the Nabesna quadrangle indicates significant variations in the densities and thicknesses of the rock units that underlie the quadrangle. Most of this gravity relief is indirectly related to regional topographic relief or lithologic variations that are revealed in the rock outcrops. However, some significant features of the gravity map are not easily explained by the map geology, and several important features on the geologic map seem to have little gravitational expression. These failures in correlation suggest that there may be considerable differences between the deep and shallow structures of the quadrangle. Understanding these differences may eventually alter the present estimates of the quadrangle's mineral potential.

Alaska↗