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At least 199 records · Page 11

Mineral exploration potential of ERTS-1 data

The author has identified the following significant results. Preliminary analysis of a mosaic composing eight individual ERTS frames (1:1,000,000) extending well beyond the test site has revealed a number of tectonic structural trends that are controlled by regional lineations. So far most of the regional lineations fall into three general directions: east by northeast, northwest, and north-south. From preliminary examination, it appears that the older Precambrian basement predominates in the NE-bearing structural trends, whereas the predominate NW trend is most likely associated with the Texas Structural Zone, and the north-south trend being the Utah-Arizona belt and/or part of the southern Basin and Range Province. One major lineation, made up of many parallel lineations, is noticeable just north of Lake Pleasant which extends for approximately 100 miles in a northern direction out of the target area. This feature corresponds to a Precambrian schist formation shown on the USGS geologic map of Arizona.

Brewer, W. A.↗

Identification of geostructures of continental crust particularly as they relate to mineral resource evaluation

The author has identified the following significant results. Preliminary examination of ERTS-1 imagery in central and northern Alaska substantiates the existence of a conjugate set of northeast and northwest faults suggested by linears noted on Nimbus 4 images. Linears of both trends are well expressed and several have been mapped as faults, including the Shaw Creek fault. Imagery provides new data to support the interpretation that the Kobuk Trench is the northern margin of a broad west-trending fault zone bounded on the north and south by strike-slip faults. In northwestern Alaska, MSS band 5 imagery shows Mississippian limestone as white, while shale, sandstone, and chert of other ages appear dark. As the limestone is the basal formation of the numerous thrust plates stacked in the area, images of band 5 will assist significantly in depicting the distribution of the thrust plates. In south-central Alaska the newly described Totshunda fault is readily identified and extends into areas not yet mapped. Also shown is another fault parallel to the south of the Totshunda which has not yet been recognized in the field.

Gryc, G.↗

Major crustal fractures in the Baltic Shield

The author has identified the following significant results. Initial analysis of the bands for images 1039-09322, 1039-09315, and 1040-09371 provide a detailed picture of a zone extending 500 km north-northeast from the northern coast of the Gulf of Bothnia. Highways (on bands 0.5-0.6 and 0.6-0.7), rivers (bands 0.7-0.8, 0.8-1.1) and bare fell tops are visible. Schist belts, as known from ground surveys, can be discerned from areas occupied by their basement rocks or major plutons. A number of sharp lineaments, apparently faults, are visible. Some major fracture zones, up to 50 km wide, that form distinct lineaments in weather satellite pictures and belong to the main objects of this study, are rather indistinct in the images but can be traced.

Tuominen, H. V.↗

Structural and lithologic study of Northern Coast Range and Sacramento Valley, California

The author has identified the following significant results. Preliminary analysis of the data received has disclosed two potentially important northwest-trending systems of linear features within the Northern California Coast Ranges. A third system, which trends northeast, can be traced with great uncertainty across the alluviated part of the Sacramento Valley and into the foothills of the Sierra Nevada. These linear features may represent fault systems or zones of shearing. Of interest, although not yet verified, is the observation that some of the mercury concentrations and some of the geothermally active areas of California may be located at the intersection of the Central and the Valley Systems. One, perhaps two, stratigraphic unconformities within the Late Mesozoic sedimentary rocks were detected during preliminary examination of the imagery; however, more analysis is necessary in order to verify this preliminary interpretation. A heretofore unrecognized, large circular depression, about 15 km in diameter, was detected within the alluviated part of the Sacramento Valley. The depression is adjacent to a large laccolithic intrusion and may be geologically related to it. Changes in the photogeologic characteristics of this feature will continue to be monitored.

Rich, E. I.↗

Mapping of the major structures of the African rift system using ERTS-1

The author has identified the following significant results. The structural margin of western Afar with the Ethiopian plateau is marked by a rather wide zone of crustal deformation. ERTS-1 imagery has now permitted a more precise mapping of the structures of this marginal zone, and in particular of the discontinuous marginal graben. The tectonic style of the graben is different in the north from the south, and in the latter region the graben is discordant with the regional tectonic trend. The structural margin of the southern Afar with the Somalian plateau is formed, in the western sector, by a remarkable series of fault-zone splays. Afar-plateau boundary fault-zones successively curve northeast and then NNE to become Afar floor fault-zones, with a distance of about 25 km separating successive turnoffs. The transition from Ethiopian rift to Gulf of Aden tread faulting along this margin is fascinatingly complex. A simplistic crustal thinning model is not adequate to explain all observed structural features of the Afar margins.

Mohr, P. A.↗

To evaluate ERTS-1 data for usefulness as a geological sensor in the diverse geological terranes of New York State

The author has identified the following significant results. In the present imagery, obtained during the full foliage of summer and fall, the greatest amount of spectral geology is displayed in the Adirondack region where bedrock geology is strongly linked to topography. Of the four spectral bands imaged, band 5 and 7 provide the most geological information. The boundary between the basement rocks of the Adirondack Dome and the surrounding Lower Paleozoic rocks is well delineated except in the Northwest Lowlands and along parts of the eastern Adirondacks. Within the basement complex, the most prominently displayed features are numerous north-northeast trending faults and topographic lineaments, and arcuate east-west valleys developed in some of the weaker metasedimentary rocks. The majority of the faults and lineaments shown on the geologic map of New York appear in the ERTS-1 imagery. In addition, many new linears were detected, as well as a number of anomalous curvilinear elements, some circular in plan and measuring up to 25 km in diameter, which do not bear any clear relationship to mapped geological contacts. The possibility that it is an astrobleme will be investigated after snow melts in the spring.

Isachsen, Y. W.↗

Applicability of ERTS-1 to Montana geology

The author has identified the following significant results. Geologic maps of four test sites were compiled at 1/250,000. Band 7 prints enlarged to 1/500,000 scale are the best for the purpose, and negative prints provide a valuable supplement. More than 100 mapped lineaments represent most of the major faults of the area and a large number of suspected faults, including many of northeast trend. Under ideal conditions dip slopes may be recognized, laccoliths outlined, and axial traces drawn for narrow, plunging folds. Use of ERTS-1 imagery will greatly facilitate construction of a needed tectonic map of Montana. From ERTS-1 imagery alone, it was possible to identify up-turned undivided Paleozoic and Mesozoic strata and to map the boundaries of mountain glaciation, intermontane basins, a volcanic field, and an area of granitic rocks. It was also possible to outline clay pans associated with bentonite. However, widespread recognition of gross rock types will be difficult.

Weidman, R. M.↗

Applicability of ERTS-1 to Montana geology

The author has identified the following significant results. Rapid construction of a lineament map for western Montana, drawn as an overlay to a late August band 7 mosaic at a scale of 1:1,000,000 indicates ERTS-1 imagery to be very suitable for quick compilation of topographically expressed lineaments representing scarps and straight canyons. Over 100 such lineaments were detected, ranging in length from 80 down to 5 miles. Most of the major high angle faults of the area are represented, but low angle faults such as the Lewis overthrust are not apparent. Short and medium length lineaments of northeast trend are abundant southeast of a line connecting Missoula and Great Falls. Only about half of the lineaments are shown on the state geologic map, and limited comparisons with more detailed maps suggest that many will merit investigation as possible faults. It is already apparent that ERTS-1 imagery will be useful in construction of a needed tectonic map of Montana.

Weidman, R. M.↗

Evaluation of feasibility of mapping seismically active faults in Alaska

The author has identified the following significant results. The Yukon-Tanana uplands north and east of Fairbanks appear, on ERTS-1 imagery, to be composed of a number of large-scale (approximately 100 kilometers square) crustal blocks. The boundaries of these blocks appear to be defined by a number of northeast-striking lineaments which form the major river valleys of the area. Principal among these are the valleys of the Salcha River, the Cehan River, and the Chatanika River. These lineaments are all seismically active, and are thus presumed to be faults. This parallel set of lineaments appears to be intersected at various angles by a secondary set of faults trending generally north to south. The larger earthquakes in the area occur at the intersections of the two sets. It appears that seismicity of this part of Alaska may be conceptually represented by the grinding together of rigid blocks, with earthquakes occurring along their common boundaries and at the intersections where three or more blocks come in contact.

Gedney, L. D.↗

Mapping of the major structures of the African rift system

The author has identified the following significant results. Lake Tara lies within a previously recognized asymmetric graben situated on the Ethiopian plateau and about 250 km west of the plateau-Afar margin. ERTS-1 imagery confirms the stronger deformation of the western side of the Tara graben, with intense faulting and some associated monoclinal mapping extending between latitudes 12 deg and 14 deg N, and lying close to meridian 37 deg E. The zone of deformation is gently arcuate in plan, trending NNE in the south NNW in the north. In the north, the Quaternary faulting dies out in the alluvial plains of the Takazze Valley; in the south the faulting appears to die out in coincidence with a large erosional escapement trending S30W from Lake Tara to precisely latitude 11 deg N. This escapement aligns with the massive NE-SW escapement of western Simien, northeast of Lake Tara, and may represent erosional recession from major faulting and tilting much older than that of the superimposed, obliquely trending Tara graben. A 30 km diameter circular feature has been identified from the ERTS-1 imagery of the Tara graben, centered on 13 deg 05 min N, 37 deg 20 min E. ERTS-1 imagery further shows that the Tara graben and its associated young volcanics have no direct connection with the Red Sea or Ethiopian rift valley.

Mohr, P. A.↗

Orientale Basin deposits (Riccioli area) in Apollo 16 earthshine photography, part E

Interpretations of photography of Orientale Basin deposits obtained under earthshine illumination conditions during the Apollo 16 mission are presented. Although the quality of these photographs is less than that obtainable in sunshine, these regions are in the dark during Apollo missions because of the locations of the Apollo landing sites. Photography of these regions under different lighting geometry and from different viewpoints is therefore a useful addition to previous photographic data. Oblique photography was obtained of Riccioli Crater and adjacent areas, which lie northeast of the Orientale Basin.

Lloyd, D. D.↗

Lunar volcanism: Mare ridges and sinuous rilles, part P

Additional evidence of the volcanic origin of mare ridges and sinuous rilles is provided by near-terminator photography of the Herigonius Rille area (12 deg S 37 deg W) northeast of Gassendi Crater. A possible genetic relationship between ridges and rilles is illustrated. From the figure, the following relationships are evident. (1) The most prominent rille crosses several ridges without distortion, which indicates that the mare ridges did not form after the sinuous rilles. (2) The rilles could not have formed by flow up and over the ridges. (3) The rilles extend from their widest ends toward distinctly lower elevations, and the largest one branches both north and south from the vent area. Elevations are evident in stereographic views that clearly indicate the local slopes. (4) The wider end of each rille is marked by an elongate vent (?) near the summit of the mare ridge from which the rille appears to issue. (5) The two most prominent rilles join south of the vent area and continue southward for more than 130 km.

Young, R. A.↗

An interpretation of a geologic map of Fannin County, Texas, prepared by ADP techniques from ERTS MSS data

Multispectral scanner data, collected by ERTS-1 from an area in northeast Texas underlain by structurally simple cretaceous sedimentary rocks, were analyzed using several automatic data processing techniques. Training areas for the computer analysis were selected in three ways using: (1) an unsupervised classifier, (2) the unsupervised classifier to further refine training areas, and (3) available ground information. The first two methods utilize the capability of the unsupervised classifier to the unsupervised classifier to group resolution elements with similar spectral properties. With the imagery produced by these procedures, several geologic features can be identified. The most easily recognizable features are streams and other water bodies. The approximate location of contacts between several rock units can be mapped.

Henderson, J. A., Jr.↗

Vigor loss in conifers due to dwarf mistletoe

Practical remote sensing techniques were developed for detecting and evaluating vigor loss in forest conifers due to dwarf mistletoe. Eastern dwarf mistletoe (Arceuthobium pusillum) infection of black spruce (Picea mariana) was investigated. A tower-tramway system, 100 feet high, was erected over an infected stand in northeast Minnesota in June and multiband/multidate photography was initiated in July and is continuing. Four 70mm film-filter combinations were used in a multicamera unit: Plus-X/Wratten 58, Plus-X/Wratten 25A, Aero Infrared/Wratten 89B, and Ektachrome Infrared/Wratten 12. The stand of mistletoe-infected black spruce under the tramway was photographed three times per day (0900, 1200 and 1500 local sun time) at approximately 10 day intervals. An extensive test site, several square miles in area, was selected in north-central Minnesota for the purpose of testing photographic specifications developed on the tramway test site. One aerial photographic flight at a variety of altitudes was accomplished over the extensive test site in August. Data analyses are not available at this time.

Meyer, M. P.↗

Viking landing sites

A valley near the mouth of the 20,000-foot-deep Martian Grand Canyon has been chosen by NASA as the site of its first automated landing on the planet Mars. The landing site for the second mission of the 1975-76 Viking spacecraft will probably be an area about 1,000 miles northeast of the first site, where the likelihood of water increases the chances of finding evidence of life.

Panagakos, N.↗

Analysis of photo linear elements, Laramie Mountains, Wyoming

The author has identified the following significant results. Photo linear features in the Precambrian rocks of the Laramie Mountains are delineated, and the azimuths plotted on rose diagrams. Three strike directions are dominant, two of which are in the northeast quadrant. Laramide folds in the Laramie basin to the west of the mountains appear to have the same trend, and apparently have been controlled by response of the basement along fractures such as have been measured from the imagery.

Blackstone, D. L., Jr.↗

Application of ERTS and EREP images to geologic investigations of the basin and range: Colorado Plateau boundary in northwestern and north central Arizona

The author has identified the following significant results. Regional mapping using ERTS-1 images has led to the recognition of two parallel northeast-trending systems of normal faults, the Bright Angel and Mesa Butte fault systems, each of which can be traced at least 100 miles. Many eruptive centers appear to be localized along these fault systems or along their extensions. The faults are chiefly observed in Phanerozoic rocks and have minor displacement, but are interpreted to reflect fault zones of major displacement in the crystalline Precambrian basement. The location of epicenters of recent earthquakes and reports of earthquakes by residents in the region suggest that the Bright Angel and Mesa Butte fault systems are currently active.

Goetz, A. F. H.↗