Page images
PDF
EPUB

ORBITAL MAPPING SYSTEM

tions, Washington, D.C., and Vicinity, published as Geological Survey Miscellaneous Investigation 1616. This report graphically illustrated the various color combinations and permutations that are possible from the six spectral bands selected for this project. The report quantitatively described the rationale behind spectral band selection to present the maximum information for a given scene.

One significant finding of this research is the establishment of a picture-element (pixel)-to-scale relationship criterion of 3.3 pixels per millimeter at map scale. This means that the 75- to 80-meter pixels of the Landsat multispectral scanner are suitable for 1:250,000-scale image mapping. The 30-meter pixels of the Thematic Mapper are suitable for 1:100,000 scale, and 15-meter pixels are needed for 1:50,000

During the past several years, a space system for mapping the Earth's surface topography has been defined. This system, called Mapsat, was patented in 1982. During 1983 and 1984, the International Society for Photogrammetry and Remote Sensing activated a committee to define an optimum system for mapping from space and requested Geological Survey personnel to organize and chair the committee. The committee's report, Acquisition and Processing of Space Data for Mapping Purposes, was submitted to the International Society for Photogrammetry and Remote Sensing during their XV Congress in Rio de Janeiro, Brazil, in June 1984. The report was accepted and is being forwarded to the various space agencies and the 73 national societies that make up the international society.

scale.

Geologic Investigations

MISSION AND OUTLOOK

During fiscal year 1984, the Geologic Division continued its programs to assess energy and mineral resources onshore and offshore, to identify and investigate geologic hazards, and to determine the Nation's geologic framework, the geologic processes that have shaped it, and their relation to long-term climatic changes.

The articles in this chapter of the Yearbook describe some of the most significant accomplishments of the Geologic Division during fiscal year 1984. We believe that these articles, while representing only a select few of the activities of the Division, show how basic geologic research simultaneously provides the opportunity for new developments in the geosciences and provides the basic information needed to conduct missions that are central to the national welfare.

earthquake hazards assessment of the Salt Lake City-Wasatch Front corridor. The 3-year study began in fiscal year 1984 and will establish the earthquake potential of the Wasatch fault zone, which is inhabited by 85 percent of Utah's population.

Landslides again were triggered by rapid melting of record mountain snowpacks in April and May 1984 and caused widespread damage in Utah along the Wasatch Front and on the Wasatch Plateau. Geological Survey landslide specialists assisted the Utah Geological and Mineral Survey during the emergencies in the search for and the identification of landslides that posed an immediate threat to public safety.

Short-term warning and monitoring of each of the numerous phases (24 as of September 1984) of the long-lived eruption of Kilauea Volcano in Hawaii that began in January 1983 continued in fiscal year 1984 under the Volcano Hazards Program. The March 25 to April 15, 1984, eruption of Mauna Loa volcano in Hawaii was forecast successfully in late 1983 by the Geological Survey. The forecast was based on monitoring results that showed high seismic activitiy and active deformation taking place near the summit of Mauna Loa.

A computer-enhanced monitoring system for Spirit Lake and other debrisdammed lakes near Mount St. Helens was installed in fiscal year 1984. The system utilizes satellite and radiotelemetry units for transmitting realtime water-level data for immediate warning of any failure of the debris dams.

MAJOR PROGRAMS

The Geologic Division program is presented to Congress under five major program headings. A discussion of accomplishments under these subactivities during this last fiscal year follows.

Geologic Hazards Surveys

Land-Resource Surveys

As a result of earthquake prediction research of the U.S. Geological Survey, the location and the magnitude of the 1984 Morgan Hill, California, earthquake were anticipated successfully. In 1980, the Geological Survey had forecast that an earthquake comparable to the 1979 Coyote Lake, California, earthquake (magnitude 5.9) might occur on the Calaveras fault in the area near Morgan Hill. Geological Survey studies had suggested that complexities (bends and offsets) in the trace of the Calaveras fault control where earthquakes start and that these barriers, when broken, produce large shocks.

The Geological Survey and the Utah Geological and Mineral Survey are conducting a joint Federal-State

During fiscal year 1984, State geologic maps for Wyoming and Massachusetts were published or approved for publication. These maps are the syntheses of hundreds of man years of research under the Geologic Framework Program and join the Kentucky State geologic map as indispensable tools for mineral- and

of California. Several of the ash layers have been found in marine deposits west of Tulelake and in deep-sea cores.

Mineral-Resource Surveys

energy-resource studies, regional tectonic syntheses, and as "state-of-theart” models for other State map compilations.

Research on the "accreted terrane” theory resulted in the completion of maps showing the lithotectonic terranes (microcontinents) of western North America including map explanations and descriptive pamphlets. This study incorporated geologic mapping, paleontologic, paleomagnetic, and isotopic research to treat the areal extent, characterization, and interrelation of more than 200 terranes that were accreted to western North America during the past 250 million years. As an example, studies of certain fossil groups found in rocks from one of these terranes suggest that it was probably once attached to what is now Eurasia or Indonesia. Measurement of the magnetic properties of rocks in many of the terranes have enabled geologists to calculate the latitude and longitude at which the rock formed; in many cases, the calculated location is thousands of miles from where the terrane currently is located. Preparation of these maps resulted from international collaboration of Geological Survey personnel with scientists from Mexico and Canada.

Continued stratigraphic studies of deep sea cores, cores from lakes, and terrestrial outcrops under the Climate Program are building a more complete understanding of climatic events. Identification of diverse paleoclimates that existed over the last 1 or 2 million years is being aided by comparing dated volcanic ash layers from onshore sites with those collected from deep-sea cores. This information, combined with oxygen-isotope analyses of microfossils found in the marine deposits, has been used to determine temperatures and climatic conditions through the time periods dated by the ashes. Of particular importance are several widespread, well-dated ash beds found in a 990-foot core at Tulelake in northeastern California. These ashes were formed by volcanic eruptions in the Cascade Range of the Northwestern United States, the Yellowstone area of western Wyoming, and the Sonoma volcanic field in the central Coast Range

Emphasis on the location of additional domestic strategic and critical mineral deposits, including the development of exploration and assessment techniques, continued to have a high priority in fiscal year 1984. Such investigations led to the recognition of a close association between concordant tourmaline-rich rocks (tourmalinites) and stratabound deposits of base metals, gold, tungsten, cobalt, and tin. This association demonstrates that tourmaline can be used as a pathfinder for these deposits.

A multidisciplinary study was initiated to assess the mineral potential of the Mesozoic basins in the Eastern United States and the buried crystalline basement of the midcontinent. Geologic theory predicts that these two relatively unexplored terranes have high potential for discoveries of chromium, cobalt, platinum, nickel, gold, and other strategic and critical minerals.

Estimates of world bauxite resources have been updated by the Geological Survey, in cooperation with the U.S. Bureau of Mines. Bauxite is the primary ore mineral of aluminum. World bauxite reserves are estimated to be 21 billion tons. Total world bauxite resources (reserves plus subeconomic and undiscovered resources) are estimated to be 55 to 75 billion tons, an increase of 5 to 25 billion tons over the previous estimate of a maximum of 50 billion tons.

Preliminary results of mineralresource assessments under the Conterminous United States Mineral Assessment Program (CUSMAP) in the Sherbrooke-Lewiston area of Vermont, New Hampshire, and Maine were presented at a public meeting in September 1984. New CUSMAP regional mineral resource assessments were initiated in the Joplin area, Missouri-Kansas, the Harrison area, Arkansas-Missouri, the Roseau-International Falls area, Minnesota, and the Redding area, California.

Mineral-resource assessments of twenty-nine 1- x 2-degree quadrangles

(an area ranging from 4,580 to 8,669 square miles) in Alaska have been completed to date. Projected plans for the Alaska Mineral Resource Assessment Program (AMRAP) are to complete a total of 100 quadrangles by the year 2000. Major mineral deposit discoveries that have been made under AMRAP include copper, zinc, tin, tungsten, lead, silver, and other base metals.

During fiscal year 1984, continuing mineral resource assessments of roadless areas of the U.S. Forest Service revealed a moderate potential for volcanogenic massive sulfide, and possibly gold, deposits. This discovery was made in the Bread Loaf Roadless Area in the Green Mountains of Vermont, a region without previously known mineral occurrences.

the uranium potential in the peat deposits in Stevens County, Washington. The Survey has integrated the NURE information into its ongoing programs to make earth science data available to the public.

Program planning and methodology development for compiling energyresource maps for all federally owned land were initiated in fiscal year 1984 to supplement the oil and gas potential maps for wilderness lands in 11 Western States that were published earlier.

The Coal Investigations Program continues to place a high priority on coal-quality research and on making the National Coal Resources Data System (NCRDS) more accessible and responsive to the needs of Federal, State, and local land managers. A series of presentations to demonstrate the type of graphs, maps, and coal-quality data available through NCRDS is being planned for fiscal year 1985. Additional information on the coal-quality research of the Geological Survey is found elsewhere in this chapter.

Energy Geologic Surveys

Offshore Geologic Surveys

An exploration technique for the discovery of very young uranium-rich peat deposits has been developed and tested in Stevens County, Washington, where uranium in peat is being mined for the first time in the United States. The technique involves the preparation of maps showing suitability for the occurrence of uranium. These are made by synthesizing selected data from bedrock, structural, and surficial geology combined with data from soil and vegetation types and with hydrological data.

During fiscal year 1984, the Department of Energy and the Geological Survey successfully accomplished the transfer to the Survey of the data that were collected, and the analyses that were conducted, under the Department of Energy's National Uranium Resource Evaluation (NURE) Program. The Survey also concluded an agreement with the Energy Information Agency to provide up-to-date estimates of the Nation's uranium resources based on research investigations, such as the discovery of

Initial studies in support of the President's proclamation of the "Exclusive Economic Zone” (EEZ) were underway in fiscal year 1984, including the completion of “Operation Deep Sweep," a cruise that included surveys "from pole to pole." Additional information on this cruise is found elsewhere in this chapter. A detailed plan for preliminary sonar image and multichannel geophysical surveys and bottom sampling of the entire 6 million square miles of the frontier EEZ within a 10-year period are being developed. This research will provide the “road maps" for the development of the vast energy and strategic and critical mineral resources of the EEZ, which is truly America's last frontier.

Research in Earthquake PredictionThe Parkfield Prediction Experiment

The 15-mile-long Parkfield, California, section of the San Andreas fault is the best understood earthquake source region in the world. Moderate-sized earthquakes of local magnitude (M7) 534 occurred at Parkfield in 1881, 1901, 1922, 1934, and 1966. The only exception to an approximate 21- to 22-year recurrence time is the 1934 shock. The 44 years between 1922 and 1966 is just twice the usual time between the shocks. Thus, the Parkfield earthquake in 1966 reestablished the regular timing pattern of the Parkfield earthquakes. If the next Parkfield earthquake conforms to the pattern, it

will occur in the next few years, most likely in 1987 or 1988.

In addition to the predictable 22 years between shocks, Parkfield earthquakes share remarkably similar, or characteristic, features. These similar features—magnitude, length, location of rupture along the San Andreas fault (rupture zone), and epicenter-define the characteristic Parkfield earthquake. The concept of a characteristic earthquake with predictable features means that the design of an earthquake-prediction experiment can be tailored to these specific characteristic features. Because the

[graphic][subsumed][ocr errors][ocr errors][subsumed][subsumed][ocr errors][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][ocr errors][subsumed][subsumed][subsumed][merged small][subsumed]
« PreviousContinue »