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John Charles Behrendt

Publications and source records attributed to John Charles Behrendt.

At least 37 records · Page 2Linked to original sources
USGS1975

Structure of continental margin off Mid-Atlantic states (Baltimore Canyon Trough)

Increasing interest in the Atlantic continental margin as a future petroleum province has resulted in several recent papers (Emmerich, 1974; Burk and Drake, 1974) that attempt to summarize the structure and stratigraphic framework of this area. Most papers tend to portray the margin as a wedge of Mesozoic and Cenozoic sediment that thins at the edge of the shelf over a "basement ridge" and then thickens again under the continental rise. Off the northeastern United States, the sediment wedge under the shelf attains a thickness of 8-11 km in the Georges Bank basin (Schultz and Glover, 1974; Mattick and others, 1974; Sheridan, 1974b; Behrendt and others, 1974) and 12 km in thickness in the Baltimore Canyon trough off the middle Atlantic states of Delaware, Maryland, Virginia and New Jersey (fig. 1). Seaward of the continental shelf and its sediment prism, Emery and Uchupi (1972, figs. 133-135) infer slump deposits (eroded in some areas) covering a buried ridge thought to extend from the Laurentian Channel to Cape Hatteras, where it splits in two. The lower slope and continental rise are inferred by Drake and later investigators to be a thick prism of deep sea sediment (turbidites, hemipelagic clays, slump deposits) overlying oceanic basement in a welt that parallels the continental edge and reaches a maximum thickness of 6 km (Emery and Uchupi, 1972, fig. 188). Our purpose is to present the results of a geophysical survey across the margin seaward of the middle Atlantic states that comments on the structural - stratigraphic framework of the margin.

Open-File Report↗
USGS1974

Atlantic OCS resource and leasing potential

Thick marine sedimentary sections and geologic structures favorable for the accumulation of petroleum are indicated in Georges Bank basin, the Baltimore Canyon trough, and the Southeast Georgia embayment. Undiscovered recoverable resources of petroleum on the Atlantic OCS are estimated to be 10 billion to 20 billion barrels of oil and 55 trillion to 110 trillion cubic feet of gas. Such estimates carry a high degree of uncertainty. Preliminary results suggest that the most favorable areas for leasing are under the deeper waters of the shelf.

Atlantic OCS, Baltimore Canyon trough, Georges Ban↗
USGS1972

Tectonic map of Liberia based on geophysical and geological surveys

Interpretation of the results of aeromagnetic, total-gamma radioactivity, and gravity surveys combined with geologic data for Western Liberia from White and Leo (1969) and other geologic information allows the construction of a tectonic map of Liberia. The map approximately delineates the boundaries between the Liberian (ca. 2700 m.y.) province in the northwestern two-thirds of the country, the Eburnean (ca. 2000 m.y.) province in the south-eastern one-third, and the Pan-African (ca. 550 m.y.) province in the coastal area of the northwestern two-thirds of the country. Rock follation and tectonic structural features trend northeastward in the Liberian province, east-northeastward to north-northeastward in the Eburnean province, and northwestward in the Pan-African age province. Linear residual magnetic anomailes 20-80 km wide and 200-600 gammas in amplitude and following the northeast structural trend typical of the Liberian age province cross the entire country and extend into Sierra Leone and Ivory Coast.

Open-File Report↗
USGS1971

Aeromagnetic map of the Bopolu quadrangle, Liberia

Aeromagnetic and total-count gamma radiation surveys were flown simultaneously during the 1967-68 dry season over the entire country and consist of approximately 140,000 km of traverse, mostly along north-south lines 0.8 km apart over land and 4 km apart over the continental shelf. Continuous photography and Doppler navigation provided horizontal control. Flight altitude was 150 m above terrain. Time variations in the magnetic field measured with a fluxgatc magnetometer were removed by adjustment at crossings of east-west control lines. Variable contour intervals of 10, 50, 250, and 1000 gammas were used depending on horizontal gradient. The airborne geophysical data obtained during the Liberian survey are being prepared in a series of maps at 1:250,000 scale showing aeromagnetic and total-count gamma radiation data for each. The index map shows the location of the quadrangles.The radioactivity map of the Bopolu quadrangle should be used with this report (Behrendt and Wotorson, 1971). The surveys were flown by Lockwood, Kessler, and Bartlett, under contract to the Liberian Geological Survey. The purpose of both surveys was to assist in the geologic mapping program undertaken cooperatively by the Liberian Geological Survey and the U. S. Geological Survey under the auspices of the Liberian Government and the Agency for International Development, U. S. Department of State. The entire country is heavily forested, access is difficult, outcrops are sparse, and thick laterite is a characteristic feature. Consequently, it was hoped that; the surveys would be useful in interpolating and extrapolating from the known geologic information and in locating potential targets for mineral exploration.

Open-File Report↗
USGS1971

Aeromagnetic map of the Buchanan quadrangle, Liberia

Aeromagnetic and total-gamma radiation surveys were flown simultaneously during the 1967-68 dry season over the entire country and consist of approximately 140,000 km of traverse, mostly along north-south lines 0.8 km apart over the land and 4 km apart over the continental shelf. Continuous photography and Doppler navigation provided horizontal control. Flight altitude was 150 m above terrain. Time variations in the magnetic field measured with a fluxgate magnetometer were removed by adjustment at crossings of east-west control lines. Variable contour intervals of 10, 50, 250, and 1000 gammas were used depending on horizontal gradient. The airborne geophysical data obtained during the Liberian survey are being prepared in a series of maps at 1:250,000 scale showing aero-magnetic and total-count gamma,radiation data for each of ten quadrangles.The index map shows the location of the quadrangles. The radioactivity map of this quadrangle should be used with this report (Behrendt and Wotorson,1971). The surveys were flown by Lockwood, Kessler, and Bartlett, undercontract to the Liberian Geological Survey. The purpose of both surveys was to assist in the geologic mapping program undertaken cooperatively by the Liberian Geological Survey and the U. S. Geological Survey under the auspices of the Liberian Government and the Agency for International Development, U. S. Department of State. The entire country is heavily forested, access is difficult, outcrops are sparse, and thick laterite is a characteristic feature. Consequently, it was hoped that the surveys would be useful in interpolating and extrapolating from the known geologic information and in locating potential targets for mineral exploration. Figure 1 shows the tectonic interpretation for sheets 1 and 2 of the map based on available geologic information (White and Leo, 1969; unpub. data in files of Liberian Geol. Survey). Figure 2 is part of the residual total magnetic intensity map of Liberia obtained by digitizing the data of the map on a one-minute grid, tying to an absolute survey (Lowrieand Escowitz, 1969) by a constant of ±25,980 It 35 gammas and, removing Cain's "Field G" (Cain and others, 1965).

Open-File Report↗