RALPH N. BAKERGeneral Electric Company-Space Division

Beltsville, MD 20705

LANDSAT Data: A NewPerspective for GeologyA review of the utilization of LANDSAT imagery for geologicalinterpretation.

T HE LANDSAT (formerly ERTS) satelliteprogram has been in existence for just

over two years, and in this brief time hasadded a whole new dimension to the study ofour Earth. Scientists from all over the worldhave used data measured by LANDSAT'ssensors (telemetered down from a580-mile-high vantage point in space) tomonitor pollution and crop growth, explorefor minerals and petroleum, and conduct ahost of other investigations ranging from

geologic mapping, mineral and petroleumexploration, and natural hazards surveys. Thecategories are arbitrary, and results of inves­tigations might fit equally well into morethan one of these.

REGIONAL STRUCTURAL STUDIES

Several investigators studied regionalstructures and their relationships in LAND­SAT imagery, availing themselves of a per­spective previously impossible to achieve.

ABSTRACT: The LANDSAT (formerly ERTS) program, while con­ceived and implemented as a research and development project, hasbeen used as an operational orbital remote sensing system providingdata of considerable value to various branches of geology. Areas inwhich the satellite imagery has been found most useful include re­gional interpretations ofgeologic structure,lupdating and verifying ofgeologic maps, mineral and petroleum exploration, and the monitor­ing of natural hazards such as large-scale erosion and seismicity.Investigations in these areas of application demonstrate the widevariety of uses presently undertaken or envisioned for the future.Many benefits have already been felt; others will be seen in the nearfuture where the promise ofmineral or petroleum concentration willbe realized through conventional ground based and satellite explora­tion techniques. LANDSAT will aid considerably in pinpointing thelikely site; "hands on" geology will do the rest.

animal migration patterns to iceberg monitor­ing. The mission, originally designed for re­search and development, has for all practicalpurposes been considered "operational"from the user's point of view.

To geologists, the regional overview andrepetitive coverage of LANDSAT data hasbeen particularly useful, enabling them totake advantage of vegetation and sun anglechanges in their attempts to unravel the phys­ical history and setting of the Earth. Success­ful LANDSAT investigations in geology canbe grouped for convenience into four generalcategories: regional structural studies,

Y. Isachsen of New York State's GeologicalSurvey used the IOO-by-IOO-mile images toconstruct a mosaic of the State and neigh­boring regions. This mosaic shows, at aglance, geologic relationships of New YorkState's diverse terrain, major rock units, gla­cial features, large scale lineaments, and cir­cular structures (Figure I). Isachsen wentinto the field to verify the existence of manyof these features discovered in the LAND­SAT mosaic, and demonstrated how onecould use satellite imagery to discern fea­tures unsuspected at a larger scale.

Houston and Marrs, LANDSAT inves-

PHOTOGRAMMETRIC ENGINEERING AND REMOTE SENSING,

Vol. 41, No. 10, October 1975, pp. 1233-1239.1233

1234 PHOTOGRAMMETRIC E GINEERING & REMOTE SENSING, 1975

FIG. 1. LANDSAT mosaic and lineament map of eastern New York State (after Isachsen, 1973).

tigators from the University of Wyoming,studied geologic structures in Wyoming byusing a LANDSAT mosaic, and reported thattheir interpretations compared favorablywith known ground truth of the region. Whilethis region had been reasonably well mappedby conventional field surveys, theHouston-Marrs study points out the possibil­ity of interpreting poorly mapped regionswith a minimum of ground truth, time, andcost with some measure of confidence.

In the East where climate is generally lessarid than in some Western States, LANDSATinvestigators have still been able to collectvaluable geologic information despite theheavier vegetation cover. For example, re­gional lineaments were discovered and map­ped by Gold and co-investigators at PennState, using LANDSAT imagery of thethickly forested Pennsylvania Appalachians.A private consulting firm has appliedcomputer-aided enhancement techniques (inthis case General Electric Company'sIMAGE 100 multispectral image processingand display system) to imagery of other areasin eastern Pennsylvania, with success in dis­tinguishing rock outcrops oflimited areal ex­tent. Thus, while imagery of arid regions hasthe obvious advantage of little interference

between surface and sensor, investigatorshave shown that much geological informa­tion can be derived from imagery where theground is obscured by vegetation.

GEOLOGIC MAPPI G

The LANDSAT overview and coveragecycle makes map correction and verification anatural application to geology. InvestigatorsH. Blodget and A. Anderson of NASA's God­dard Space Flight Center constructed athree-image mosaic of southern Moroccofrom which they were able to verify and mod­ify previously mapped lithologic boundaries,and investigate relationships between struc­tural character and mineral emplacementfrom a regional perspective. A common pro­cedure among LANDSAT investigators hasbeen to use the imagery as base maps uponwhich geologic interpretations of structure,lithology, and lineament patterns aresuperimposed. Another team of inves­tigators, M. Abdel-Gawad and J. Silversteinof Rockwell International, discovered thatLANDSAT images of Baja and the Gulf ofCalifornia showed several small islands tohave been misplaced on conventional maps,both in geographic location and in topo­graphic detail.

LANDSAT DATA: A NEW PERSPECTIVE FOR GEOLOGY 1235

M. Viljoen ofSouth Africa used LANDSATimagery to unravel the geologic relationshipsof the South African shield. This investigatorwas able to distinguish between the granite­gneiss craton, adjacent metomorphic mobilebelts, and major "greenstone" intrusions.The nature of these intrusions and theircharacteristic relationship to the overallgeologic setting was recognized by Viljoen tobe similar to that found in metallic mineralmining districts in Canada (e.g., Sudbury,Ontario) and Western Australia, and suggeststhat the South African regions might containuseful concentrations of minerals as well. Inthis example, the roughly 34,OOO-square­kilometer region surveyed in a singleLANDSAT frame could be broken down intomineralization potential maps with consid­erable savings in time and cost to mineralexploration interests. On a larger scale,perhaps the most impressive display ofLANDSAT's map~making capability can beseen in the mosaic of the 48 conterminousUnited States, produced by the Soil Conser­vation Service of the U. S. Department ofAg­riculture, and available to the public (Figure2).

MINERAL AND PETROLEUM EXPLORATION

The majority of LANDSAT geology inves­tigations fall into this category primarily be­cause of the direct impact on current and pro­jected national needs. Mineral exploration

from LANDSAT has been accomplishedusing the following well-known geologicprinciples:

• Mineralizing fluids from within the Earthmay follow the paths of least resistance tothe surface; these paths are zones of weak­ness through the Earth's crust and occurwhere the solid rock has been fractured andfaulted. Thus, a concentration of "linea­ments", many of which can be discerned inLANDSAT imagery, may well indicatewhere the crust is weakest and, therefore,most likely to be mineralized.

• Some rock types discernible from orbitalaltitudes are characteristically associatedwith certain types of minerals because theyindicate similar formative conditions or alt­eration through time.

• Mineralization may alter surface tones bysecondary enrichment, vegetation stressandJor chemical changes in the vicinity ofthe ore body, all of which can indicate thatsignificant mineral concentration has takenplace.

Using these and other, more subtle clues,geologists using LANDSAT imagery havereported varying degrees of success in min­erai and petroleum exploration studies. Someof these investigators have relatedLANDSAT-discovered Iineaments to knownmineral concentrations; many of thesestudies have been undertaken in the arid re­gions of Western North America. E. Lathramand other geologists of the U. S. GeologicalSurvey discovered a series of intersecting re-

FIG. 2. Mosaic of continental United States compiled from LANDSAT imagery by USDA.

1236 PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING, 1975

gional lineaments in a rare cloud-free NIM­BUS image ofAlaska. These lineaments wereverified in LANDSAT imagery and enabledthe investigators to propose a radically dif­ferent picture of mineral emplacement inAlaska. Earlier speculation suggested thatmineral deposits in Alaska were related tofold belts of the Canadian Cordillera. Basedon the occurrence of the newly discoveredregional fractures, Lathram and his cowork­ers suggested that mineral emplacementmight also have occurred at their intersec­tions. The result is an alternate hypothesis formineral emplacement in Alaska, certain tostimulate interest in renewed exploration ef­forts in areas formerly dismissed as non­productive (Figure 3).

Further to the south, California inves­tigators E. Rich (1973), Abdel-Gawad, andSilverstein (1973) correlated mininglocalities with lineaments observed inLANDSAT imagery. Abdel-Gawad and Sil­verstein, in particular, correlated mercurymining localities with a newly discovered setof transverse faults in the Coast Ranges. Thealtered serpentine host rock and geologic set­ting of the mercury ore were non-definitive

EXPLANATION_Ni,Cr,FeCIIJ Cu, Mo, massive sulfides= "9. Sb.W- Mojor foult with surface

expression

EXPLANATION=Hg. Sb. W_Ni,Cr.FemJ Cu, Mo, mossi...e sulfide...... Crustal fractures- Mojor foult with surface expression

FIG. 3. Projected distribution of selected min­erals in Alaska (after Lathram et aI., 1973). A.Theory ofassociaton with geosynclinal evolutionof western Cordillera. B. Theory of associationwith crustal fractures as observed in satellite im­agery.

and of little value as ore guides. With therelationship demonstrated by these inves­tigators, future exploration efforts should besimplified markedly (Figure 4). AnotherCalifornian, 1. Bechtold, demonstrated asimilar correlation between tensional fis­sures in the Lake Mead area (resulting fromeast-west crustal extension) and concentra­tions of gold, silver and other metallic oredeposits.

An interesting multilevel geochemical ex­ploration approach was reported by M. Jen­sen, ofthe University ofUtah, who correlatedLANDSAT lineaments with positive aero­magnetic anomalies, and field-checked areaswhere they coincided. Soil samples wereanalyzed for mercury vapor, and those areasof highest mercury vapor concentration iden­tified for intensive exploration.

Other investigators have attempted to cor­relate mineral deposits with characteristicsurface tones extracted from LANDSAT im­agery visually or by computer enhancementtechniques. R. Vincent identified highly ox­idized terrain overlying iron ore deposits inthe Atlantic City mining district of Wyomingby computer ratioing reflectance values ofselected pairs of ERTS bands. The resultswere analog ratio images, corrected forgeometric and atmospheric effects, whichshowed the oxidation "halos" over the ironore deposits. A. Goetz and others at JPL de­veloped computer techniques for rock iden­tification and structural analysis in the Col­orado Plateau, eventually resulting in thediscovery of perched aquifers, ground watersources badly needed by ranchers on theCoconino Plateau of southern Arizona.

LANDSAT data have found application inpetroleum exploration as well. Two investig­ations have met with initial success in thisarea. E. Lathram in another phase of thestudy mentioned earlier discovered an un­usual regional orientation in a series oflakeson the Alaskan Arctic Coastal Plain. Thelakes, generally oval in outline, paralleledregional lineations and deviations in the localgravity and magnetic fields. Supportingground truth coupled with LANDSAT dataled the investigators to postulate the exis­tence of"dip" reversals and regional arching:factors which might indicate potential pe­troleum accumulation (Figure 5). Similargeologic trends continue to the northeast,and have aroused the interest of the pe­troleum industry.

Another investigation, headed by R. Col­lins of Eason Oil Company (Oklahoma City),correlated "hazy" surface tones discoveredin LANDSAT imagery of the Anadarko Basin

N )4"

LEGEND

~ ... Fault with evidenceof recent movement

KNOW FAULTSFAULTS INFERRED FRO.... ERTSDRAINAGE LINE

.....ERCUR" ltliNG DiSTRICT• MERCURY INES

Abde I·Gawad & Si I verste i n 1973

EARTHQUAKE EP IeENTERSL!l- ~RGNI TUDE UNKNOWN'-~AGNITUDE O. - 4.0x-~AGNtTUDE 4.1 - 4.9O-MAGNITUDE 5.0 - 5.4x- MAGN I TUDE 5.6 - 6·8.-~RGNITUDE 6.0 - 6.9K-~AGNITUDE 1.0 - 7,9.-~AONIrUDE ~·o - ~.4

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t"">ZoVl

~o>..,?­>Zt'l~'"0t'l::0Vl'"0t'l(")..,:<t'l"r1o::0(')t'lot""o(')-<

FIG. 4. LANDSAT imagery of southern California and a plot of faults (after Abdel-Gawad and Silverstein, 1973),

""""1'0W-1

1238 PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING, 1975

FIG. 5. Lake orientation and associatedgeophysical lineations on the Alaskan arcticcoastal plain (after Lathram et aI., 1973).

(NE Texas and SW Oklahoma) with knownproducing oil fields. Correlation exceeded 85per cent, and led the investigators tohypothesize that these surface anomalieswere the result of volatile components of thepetroleum reservoirs migrating to the sur­face. Whether this phenomenon is a conse­quence of well drilling or is a natural occur­rence remains to be proven.

EARTH HAZARDS: MONITORING AND SURVEYS

Geologic hazards present a direct threat tosociety in several familiar ways. The catas­trophic result of earthquakes and volcaniceruptions, and the less spectacular butequally devastating effects of erosion andflooding can be monitored and better under­stood through the synoptic and repetitiveoverview provided by LANDSAT 1 and 2.

LANDSAT investigators have successfullyused orbital imagery to inventory, monitor,and even forewarn of potential geologiccatastrophes. Among these are USGSgeologists Eaton and Ward, who usedLANDSAT to relay information from a seriesof data collection platforms emplaced on ac­tive, potentially eruptive volcanoes in Alaskaand Central America. DCP instrumentationconsisted of seismic event counters and borehole tiltmeters, both designed to relay datacharacteristic of the pre-eruptive phase of thevolcano. The investigation proved successfulwhen the volcano F'uego, in Guatemala,erupted with devastating force shortly afterinformation relayed from the DCP indicatedit would.

o 25 MILESJI--~I---11o 25 KILOMETERS

1004-21395

Other Earth hazards include the poten­tial of earthquakes in many parts of theworld. LANDSAT facilities for locating re­gionallineaments have been used by inves­tigators dealing with these hazards. M.Abdel-Gawad discovered evidence of recentmovement along faults in southern Californialong considered to be inactiveJ Seismichazards maps can be modified by inputs ofthis type provided by LANDSAT sensors.

L. Gedney of the University of Alaska'sGeophysical Institute constructed a mosaicof central Alaska using six LANDSAT im­ages, clearly revealing the presence of sets of"lineaments" (faults and fractures) whichcorrelated well with the distribution of shal­low focus earthquake epicenters in the re­gion. Through these studies, an active leg ofthe Denali fault was found to lie close to abridge site over the Yukon River, and theproposed route of the Alaskan oil pipeline.Updated seismic data coupled with LAND­SAT imagery will enable planners to modifytheir route selections as necessary.

Perhaps less catastrophic but equally dev­astating in the long term is the problem ofsoil erosion. Morrison ofthe U. S. GeologicalSurvey dealt with regions of accelerated ero­sion in southern Arizona. Present erosiondamage was monitored by LANDSAT, flood­ing and floodwater recession observed, andan erosion-susceptibility map constructed asan aid to future development.

LANDSAT programs have made signifi­cant contributions to many subspecialitieswithin geology. Some of these contributionshave already been felt in terms of correctedmaps and a more accurate awareness of pre­vailing seismic hazards.

Some will be felt in the future, where thepromise of undiscovered mineral and pe­troleum deposits can be fulfilled throughcomputer enhancement of LANDSAT datacombined with visual interpretation andsupporting ground truth.

Data collected by LANDSAT's sensors canprovide a wealth of information useful forsolving the problems facing man as he tries tolive in harmony with his environment. Onlythoughtful interpretation of the data, sup­plemented by the technology of moderncomputers, will enable him to maximize thebenefits "for all mankind."

REFERENCES

Abdel-Gawad, M., and J. Silverstein, 1973, "ERTSApplications in Earthquake Research andMineral Exploration in California,"Symposium on Significant Results Obtainedfrom the Earth Resources Technology

LANDSAT DATA: A NEW PERSPECTIVE FOR GEOLOGY 1239

Satellite-l, Vol. I Technical Presentations p.433-450

Bechtold, 1., M. Liggett, and J. Childs, 1973, "Re­gional Tectonic Control ofTertiary Mineraliza­tion, and Recent Faulting in the SouthernBasin and Range Province, an Application ofERTS-I Data," Symposium on Significant Re­sults Obtained from the Earth ResourcesTechnology Satellite-l, Vol. I, Technical Pre­sentations p. 425-432

Blodget, H. W., and A. T. Anderson, 1973, "AComparison ofGemini and ERTS imagery ob­tained over Southern Morocco," Symposiumon Significant Results Obtained from theEarth Resources Technology Satellite-l, Vol.I Technical Presentations p. 265-272

Collins, R. J., McCown, F. P., Stonis, L. P., andPetzel, G., 1973, "An evaluation of the suita­bility of ERTS data for the purposes of pe­troleum exploration", presentation G-17, ThirdERTS Symposium, December 10-14, 1973

Gedney, L. D., and J. D. Van Wormer, 1973,"Some aspects ofactive tectonism in Alaska asseen on ERTS-I imagery," Symposium onSignificant Results Obtained from Earth Re­sources Technology Satellite-l, Vol. I, Tech­nical Presentation p. 451-458

Goetz, A. F. H., F. Billingsley, D. Elston, 1. Luc­chitta, and E. Shoemaker, 1973, "Preliminarygeologic investigations in the ColoradoPlateau using enhanced ERTS images,"Symposium on Significant Results Obtainedfrom the Earth Resources TechnologySatellite-l, Vol. I, Technical Presentation p.403-411

Gold, D. P., R Parizek, and S. Alexander, 1973,"Analysis and Application ofERTS-1 Data forRegional Geological Mapping," Symposiumon Significant Results Obtained from theEarth Resources Technology Satellite-l, Vol.I Technical Presentations p. 231-246

Houston, R S., R Marrs, R. Breckenridge, and D.Blackstone, Jr., 1973, "Application of theERTS System to the Study of Wyoming Re­sources with Emphasis on the use of BasicData Products," Symposium on SignificantResults Obtained from the Earth ResourcesTechnology Satellite-l, Vol. I Technical Pre­sentations p. 595-620

Isachsen, Y., R Fakundiny, and S. Forster, 1973,"Evaluation of ERTS-I Imagery for Geologi­cal sensing over the Diverse Geological Ter-

rains of New York State," Symposium on Sig­nificant Results Obtained from the Earth Re­sources Technology Satellite-l, Vol. I, Tech­nical Presentations p. 223-230

Jensen, M., 1973, "Geology of Utah and Nevada byERTS-I Imagery," Symposium on SignificantResults Obtained from the Earth ResourcesTechnology Satellite-l Vol. I, Technical Pre­sentations p. 247-256

Lathram, E., Tailleur, I., Patton, W. W., andFischer, W. A., 1973, "Preliminary GeologicApplication of ERTS-I Imagery in Alaska",Symposium on Significant Results Obtainedfrom the Earth Resources Technology Satel­lite 1, Vol. I, NASNGoddard Space FlightCenter, Greenbelt, Md. p. 257-262

Morrison, R B., and M. E. Cooley, 1973, "Applica­tion of ERTS-I Multispectral Imagery toMonitoring the Present Episode of Acceler­ated Erosion in Southern Arizona,"Symposium on Significant Results Obtainedfrom the Earth Resources TechnologySatellite-l, Vol. I, Technical Presentation p.283-290

Rich, E. 1., 1973, "Relation of ERTS-I detectedgeologic structure to know economic ore de­posits", Symposium on Significant ResultsObtained from the Earth Resources Technol­ogy Satellite-l, Vol. I, NASNGoddard SpaceFlight Center, Greenbelt, Maryland, p.395-402

Viljoen, R., 1973, "ERTS-I Imagery as an aid to theunderstanding of the Regional Setting of BaseMetal Deposits in the North West Cape Prov­ince, South Africa," Symposium on Signifi­cant Results Obtainedfrom the Earth ResourcesTechnology Satellite-l, Vol. I, Technical Pre­sentations p. 797-806

Vincent, R, 1973, "Ratio Maps of Iron Ore De­posits, Atlantic City District, Wyoming,"Symposium on Significant Results Obtainedfrom the Earth Resources TechnologySatellite-l, Vol. I, Technical Presentations p.379-386

Ward, P., J. Eaton, E. Endo, D. Harlow, D. Mar­quez, and R. Allen, 1973, "Establishment,Test and Evaluation of a Prototype VolcanoSurveillance System," Symposium on Sig­nificant Results Obtained from the Earth Re­sources Technology Satellite-l, Vol. I, Tech­nical Presentations p. 305-315

Notice

The listing of the Officers of Committees of the Society in the July 1975 Yearbook issue(Page 833) showed A. Trachsel as Chairman of the Publications Committee, whereas L. W.Swanson is, in fact, the Chairman of the Publications Committee.