Imágenes de páginas

On the basis of work by several authors (Maurin and Lathram, 1977),

(Fischer and Lathram, 1973) plans are now being made (Gryc, written

communication, 1977) to drill a Lands at-detected apparent geologic

structure in northern Alaska to a depth of approximately 19,775 feet this

coming year.

The results, if favorable, will help establish Landsat as an

important exploration tool.

Over 600 representatives from a number of petroleum and petroleum

exploration companies attended the most recent William T. Pecora Symposium

in Sioux Falls, s. D., in October of 1977. Both in presented papers and

in private discussions, it became apparent that the petroleum industry 18

not only the largest single customer of data from Landsat, but that they

are now using the data routinely to improve their total exploration

and planning programs.

Many companies have established their own

computerized data listings, and several are routinely using computer

analysis methods in addition to conventional interpretation procedures.

One company representative stated that the characteristics of

broad overview and low sun angle perspective provided by Landsat images

have enabled his company to select targets for detailed geological and

geophysical exploration. Another representative stated that Landsat

Images of the United States are being used extensively and are providing

new structural information that will extend known oil fields in the

United States.

Miller (1977) demonstrated how Landsat data have assisted in

exploration in Kenya.

He states that "ERTS (Landsat) studies have the

advantage of very quick Interpretation over new areas and regions.


work saves time and money and gives a substantial basis for new ideas."

In 1977 he reported the discovery of a large and thick sequence of

sedimentary rocks in southern Sudan that provide a new target for oil

exploration, which is now underway (Miller and Vandenakker, 1977).

Mosaics of the conterminous United States compiled by the Soil

Conservation Service for NASA have been analyzed by U.S. Geological Survey

geologists interested in linear features that may be of tectonic


Mosaics at scales of 1:5,000,000 and 1:1,000,000 were used

to identify and evaluate new features and to re-evaluate previously

known geologic features.

Field work in northern Sonora, Mexico, has

confirmed early interpretations by Salas (1977) that the occurrence of

major mineral deposits are closely related to the intersection of linear

features that are major fracture systems.

This confirmation is

supported by geochemical and geophysical evidence (Raines, 1977, and

Kleinkopf and others, 1977).

Rowan and others (1974) demonstrated that the combination of digital

computer processing of band ratios and color compositing of Landsat

Multispectral Scanner (MSS) images could be used to detect and map areas

of hydrothermally altered rocks associated with ore deposits and to

discriminate most major rock types in south-central Nevada.

Schmidt (1976) used computer enhanced Landsat imagery to examine the

characteristics of known copper deposits in Pakistan.

He then examined

the imagery to find areas that have similar spectral and textural


He found 19 areas that he considered to be potential

sites for the presence of mineralized rock and was able to confirm

surface mineralization by field inspection at seven of these.


similar methods, Dykstra and Bimic (1977) have extended the geologic

Information of the area to the east and confirmed many of the early


Use of Landsat to observe water-quality conditions

Landsat data have been successfully used in water-quality and environmental applications. The Program of the International Hydrological

Decade (IHD) had as a major objective the monitoring of water-quality

conditions in the Great Lakes.

As an adjunct exercise to the IHD,


EROS Program collaborated with the National Oceanic and Atmospheric

Administration (NOAA), NASA, the Canada Centre for Inland Waters, and

Guelph and McMaster Universities in studying the applicability of

Landsat data.

Falconer and others (1975) used photo-optical techniques

to enhance water features recorded in the data and clearly showed turbidity

plumes from the Welland Canal and Niagara River. They also showed

turbidity pattems interrupted by offshore bars, and steel mill and

municipal effluents in Hamilton Harbour.

Tonal differences extending into

the lake from the Humber River at Toronto were clearly depicted as well as

additional unidentified effluent discharges.

The study demonstrated

the capability of Landsat to detect sources and movement of natural

pollutants and municipal and industrial wastes into major water bodies. Linear features, presumably Internal waves, which are indicative of

lake dynamics, were also depicted on the enhanced imagery.


of floating or near-surface biotic materials were detected, illustrating

the suitability of the data for certain types of ecological analyses.

Allan Strong of NOAA, in cooperation with the EROS Program, prepared

& water-quality classification of eastern Lake Ontario using digital

analysis techniques and color codings to distinguish carbonate precipitates, chlorophylls, algae, and floating oil slicks.

The Lake Ontario study

exemplifies a potential use of Landsat in providing a small-scale

assessment of pollution, internal lake dynamics, and water quality that

could not be acquired routinely from any other single, existing source.

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