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Michael A. Fisher

Publications and source records attributed to Michael A. Fisher.

28 records · Page 2Linked to original sources
USGS1980

Preliminary free-air gravity map, Norton Basin, Alaska

Gravity data shown here were measured with LaCoste and Romberg sea gravimeter S-53 mounted on a 3 axis inertial platform (LaCoste and others, 1967, Valiant and LaCoste, 1976). Primary navigation was by satellite, integrated with course and speed measurements from doppler sonar and gyrocompass. Gravity data were filtered prior to recording with a four-minute averaging filter to remove high frequency effects of ship motion and with an 84 minute notch filter to remove Schubert-period oscillations. The gravity computer applied a correction for "inherent" cross coupling error (LaCoste and others, 1967).

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USGS1980

Petroleum potential, environmental geology, and the technology for exploration and development of the Kodiak lease sale area #61

The Kodiak lease area is along a convergent ocean margin where active subduction is probably the greatest single influence on the geology. This influence is indicated by the Aleutian Trench, the Aleutian chain of volcanoes, and a well developed Benioff zone of earthquakes. Crustal structure under the Kodiak Shelf is intermediate between continental and oceanic. The thickness of sedimentary rock is 8 ± 3 km, which is greater than beneath the island. The proposed lease—sale area is on a submerged shelf extending 100 km or more seaward from the Kodiak group of islands, and it is more than 400 km long. The Kodiak Shelf still retains a glacial topography which has been modified by tectonically uplifted banks along the shelf edge and across the shelf. These banks are readily detectable signs of recent tectonism. Not so easily detectable are three deep offshore Neogene basins formed by depression of an unsampled presumed Paleogene sedimentary section. The basin floors have subsided 5 to 7 km since middle (?) Miocene time; the basins are filled with late Miocene and younger sediment that is only gently deformed. A sudden increase in seismic velocity occurs across the contact between the basin fill and the presumed Paleogene rocks that underlie it. This discontinuity in seismic velocity, the smooth character of the basin surface, and the truncation of dipping beds beneath it, are the basis for inferring subaerial erosion of the Paleogene section. If this inference is correct, the structure in some places requires at least 3000 m of subsidence followed by an uplift of even greater magnitude in Neogene time. The vertical tectonism offshore might produce reservoir rock and different source rock than encountered onshore.

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USGS1979

Resource report for proposed OCS lease sale 57: Norton Basin, Alaska

This report is a summary of information about an area of the northern Bering Sea continental shelf that is bounded by the Seward Peninsula on the north, by the line of the United States-Russia Convention of 1867 on the west, and by St. Lawrence Island and the coastline that rims Norton Sound on the south and east. Scholl and Hopkins (1969) report that a sedimentary basin underlies the offshore area. More recent data, which form the basis of part of this report, show the basin is deepest beneath Norton Sound; also, the basin has sufficient depth and areal extent that the basin may be a target for development of hydrocarbon resources after Outer Continental Shelf (OCS) Lease Sale 57. The informal, but widely used, name for the basin is Norton Basin. The following discussion includes regional geology, geologic history, and offshore structure and stratigraphy as background data to discussion of the hydrocarbon potential and resource appraisal of the offshore area. Sections on environmental geology and on the technology and manpower needed and available for development of offshore resources are also included.

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USGS1978

Geologic framework of lower Cook Inlet, Alaska

Three seismic reflectors are present throughout the lower Cook Inlet basin and can be correlated with onshore geologic features. The reflections come from unconformities at the base of the Tertiary sequence, at the base of Upper Cretaceous rocks, and near the base of Upper Jurassic strata. A contour map of the deepest horizon shows that Mesozoic rocks are formed into a northeast-trending syncline. Along the southeast flank of the basin, the northwest-dipping Mesozoic rocks are truncated at the base of Tertiary rocks. The Augustine-Seldovia arch trends across the basin axis between Augustine Island and Seldovia. Tertiary rocks thin onto the arch from the north and south. Numerous anticlines, smaller in structural relief and breadth than the Augustine-Seldovia arch, trend northeast parallel with the basin, and intersect the arch at oblique angles. The stratigraphic record shows four cycles of sedimentation and tectonism that are bounded by three regional unconformities in lower Cook Inlet and by four thrust faults and the modern Benioff zone in flysch rocks of the Kenai Peninsula and the Gulf of Alaska. The four cycles of sedimentation are, from oldest to youngest, the early Mesozoic, late Mesozoic, early Cenozoic, and late Cenozoic. Data on organic geochemistry of the rocks from one well suggest that Middle Jurassic strata may be a source of hydrocarbons. Seismic data show that structural traps are formed by northeast-trending anticlines and by structures formed at the intersections of these anticlines with the transbasin arch. Stratigraphic traps may be formed beneath the unconformity at the base of Tertiary strata and beneath unconformities within Mesozoic strata.

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USGS1977

Geologic framework of lower Cook Inlet, Alaska

Lower Cook Inlet is located in south-central Alaska between lat 58°45' and 60°30' N. and between long 151° and 154° W. (fig. 1). Geographic features on the perimeter of the area are the Aleutian Range on the northwest, Kalgin Island on the northeast, the Kenai Peninsula on the east, the Barren Islands on the southeast, and the Kamishak Hills-Cape Douglas area on the south. Augustine Island, a prominent active composite volcano, is in the southwestern part of lower Cook Inlet. Lower Cook Inlet is part of a large bay that is nearly surrounded by mountains except where it opens southeastward into the Gulf of Alaska and southward into Shelikof Strait. In anticipation of oil and gas lease sales in lower Cook Inlet, the U.S. Geological Survey acquired geological and geophysical data to study the geologic framework and petroleum geology of this area. These data were included in the lower Cook Inlet environmental impact statements (Alaska Outer Continental Shelf Office, 1976a, b) and are being made available to other government agencies and the public.

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USGS1976

Interpretation and description of seismic data from Lower Cook Inlet, Alaska

A coarse grid of 480 kilometres of seismic lines was collected in lower Cook Inlet, Alaska between Homer on the north and Cape Douglas on the south. Paper and mylar copies of the seismic sections and shot point maps are available to the public from NOAA in Boulder, Colorado. The seismic data shows two strong reflections that have been interpreted as returns from erosional surfaces and a third reflection that represents the acoustic basement. From indications in the seismic data, shallow reflectors onlap to the northwest; deep reflectors onlap to the southeast. A major structural feature in lower Cook Inlet is an east-trending transbasin arch here informally named the Augustine-Seldovia arch. Anticlines smaller than the arch trend approximately northeast and may offer good structural traps for petroleum where they intersect the arch.

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